ENERGY DEPENDENCE OF THE EFFECTIVE INTERACTION FOR NUCLEON-NUCLEUS SCATTERING by Helmut Seifert Dissertation submitted to the Faculty of the Graduate School of The University of Maryland in parti al fulfillment of the requirements for th e degree of Doctor of Philosophy 1990 (I I \., L??_ I. J. J r { Advisory Committee: Dr. James J . Kelly, Advisor Dr . Chia-cheh Chang Dr. Nicholas S. Chant I t r/ ) ~ Dr . Stephen J . Walla ce Dr. Timothy M. Heckman Sc..'1frd 1 / l . Vu,? / ,--I) __ ~) Abstract Title of Dissertation: Energy Dependence of the Effective Interaction for Nucleon-Nucleus Scattering Helmut Seifert, Doctor of Philosophy, 1990 Dissertation directed by: J ames J . Kelly, Associate Professor Department of Physics and Astronomy We have measured cross sections and analyzing powers for 40 ,42 ?44 ?48Ca and 160 at IUCF using the new high-resolution K600 spectrometer for 100 and 200 Me V protons . Measurements at 318 Me V for 40 ?42 ?44 ,48Ca and 32 ,34 S were done at LAMPF using the HRS spectrometer. In this work, we obtain empiri cal effective interactions by fittin g inelas- tic scattering data for many low-lying normal-parity isoscalar excitations of the self-conjugate nuclei 16 0 and 4?Ca, assuming a local tp folding model. One-nucleon transition densities are from (e, e') . The fitt ed interactions are iterated to generate optical potentials self-consistently. We find that the fitt ed parameters are essentially target independent, which supports the va- lidity of the local density hypothesis . Elastic scatte ring is predicted by ex- tracting the rearrangement factor (1 + pd/ dp) from the fitt ed inelast ic inter- actions. Below 300 Me V the stre11gth of the empirical int eraction is r .du ced at zero density and th e general density dependence is weaker compared to the theoretical interaction . Above 300 MeV we find the density dependence is stronger than expected. The empirical interactions provide better descrip- tions of elastic and inelastic data than IA calculations or LDA calculations using theoretical G-matrices, and can be used for nuclear structure studies of other nuclei . Fitted optical potentials above 300 MeV are comparable to equivalent Schrodinger potentials from the relativistic IA2 model. Dedication To all the ones I love: my family, my fri ends and Tuleen Parveen 11 Acknowledgements I first would like to thank my ad visor , J ames J . Kelly, fo r guiding me through all these years of exciting research , and for suggesting this interesting dissertation topic . I also want to thank him for helping me through the for me as a foreign student sometimes difficult time at the beginning of m y graduate career . I would like to thank the Experimental Nuclear Physi cs gro up as a whole-faculty, staff, and all my collegues- for providing a very pleasant work atmosphere which I will always fondly remember. To my famil y goes, of course, my deepest gratitude for their neverending support. During my time here in Maryland I have also met some very special people who have become very good fri ends of mine, and whom I want to mention here . First, there are Raul and Steve, and especially Grace, who have shared all the good times and bad times with me, and who were always there for me . J ohn and Sabrina, George and Liz I want to thank for having invited me so many times to spend the holidays together with th eir wond erful family. Finally, last but certainly not least , there is Tulee 11 Parveen who will always be in my heart. llJ Contents List of Tables IX List of Figures XVI 1 Introduction 1 2 Theoretical Background 11 2.1 The Transition Matrix as an Effective Interaction 11 2.2 Elas tic Nucleon-Nucleus Scattering- T he Opti cal Model 13 2.3 Multiple Scattering Approach 16 2. 3.1 Introduction . . .. . . 16 2.3.2 The Full Folding P otential and its Approxim ations 18 2.3.3 Expressions for the Mixed Target Density 22 2.3.4 A Local Pseudopotenti al 24 2.3.5 Off-Shell T -Ma.trices .. 28 2.3.6 NRIA Calculation Results 30 2.4 Nuclear Matter Approach 48 2.4 .1 Int roduction . . . . 48 2.4. 2 Density Dependent Interactions 51 2.4.3 The Local Density Approxi mation 62 2.4 .4 Treatm ent of the Exchange In teraction 64 2.4 .5 LDA Calculation Results .. 66 2.5 Relativistic Impulse Approximat ion 86 2.5 .1 Introduction . . . .. . .. . 86 IV 2.5 .2 The IA2 Model ..... . .. . 87 2.5.3 The Virtual P air Interpretation 90 2.5.4 IA2 Calculation Result s . 95 2.6 Off-Shell Effects and Full-Folding 104 2.7 Inelastic Nucleon-Nucleus Scattering 107 2. 7.1 Distorted Wave Approximation 107 2. 7. 2 The Perey Effect . . . . . 109 2. 7.3 The Rearrangement Effect 111 2.8 An Empirical Effective Interaction . 113 2.8.1 Description of Theoretical Interactions 113 2.8.2 Description of Data . . . . . . . . . . . 131 2.8.3 Linear Expansion Analysis and Fitting P rocedure 135 3 Experiment 140 3.1 Introduction 140 3.2 Accelerator and Beam 141 3.3 Targets . 146 3.4 Spectrometer 147 3.4.1 The K600 Spectrometer 147 3.4.2 The HRS Spectrometer . 150 3.5 Detectors 150 3.5. 1 Scinti lla.tors 15 J 3.5.2 Wire Chambers 151 3.6 Elect ronics . 152 V 3.6.1 Scintillator Electronics . . 152 3.6.2 VDC Readout Electronics 153 3.6.3 Coincidence Electronics 157 3.6.4 Electronics for Integrators and BL 2 160 3.6.5 Data Acquisition . .. . . ... . . . 162 4 Calibrations 163 4.1 Matching Between Beam Line and Spectrometer 163 4.2 Scattering Angle 171 4.3 Beam Polarization 184 4.4 Other Calibrations and Tests 189 5 Drift Chamber Detectors 193 5.1 Introduction . .... . 193 5.2 Classification of Events 198 5.3 Calculation of Position and Angle 207 5.4 Drift Cell Resolution- Straightness of Tracks . 214 5.5 Summary and Conclusions 216 5.6 Some Diagnostics .. . . . 218 6 Data Reduction 221 6.1 Replay .. .. 22 1 6.2 Line-shap e Fitting 227 6.3 Formulae For Cross Sect ions and Analyzing Powers 237 6.4 Kinematic Formulae 240 VJ 6.5 Normalizations 241 6.5 .1 100 MeV Cups 242 6.5.2 200 MeV Cups 243 6.5.3 Normalizations between Targets 243 6.6 Cross Section and Analyzing Power Results 245 6.6.1 Fitted Data 245 6.6.2 Some General Observations 249 6.7 Results and Treatm~nt of Errors . 252 7 Results and Discussion 290 7.1 Data Selection and Iteration Procedure 290 7.2 Fit to Inelastic Data 293 7.2.1 100 MeV . 293 7.2.2 200 MeV. 306 7.2.3 318 MeV . 317 7.2.4 500 MeV. 330 7.2.5 Interior Sensitivity 336 7.3 Inclusion of the Perey Effect 339 7.4 Inclusion of Elastic Data 342 7.5 A Dependence of the Effective Interaction 351 7.6 Comparison with IA2 and Dirac Phenomenology 367 7.7 En ergy Dependence of the Effective lnternction 382 7.8 Outlook .. 390 8 Summary and Conclusions 392 VII A Nuclear Densities 399 B Differential Recoil Diagrams 408 C RAYTRACE Simulations of the K600 412 D Effective Interaction Grids 422 E List of Runs 427 F Data Tables 441 F .1 9 Be(p,p') and 16O(p,p') at Ep = 100 MeV . 44 1 F .2 4?Ca(p,p') at Ep = 100 MeV . .. . ... . . 468 F .3 9 Be(p,p') and 16O(p, p') at Ep = 200 MeV 490 F.4 4?Ca(p, p') at Ep = 200 MeV . 523 References 545 VIIJ List of Tables 2.1 Reparametrization of the PH interaction 119 2.2 Reparametrization of the NL Interaction 120 2.3 Reparametrization of the LR Interaction 121 2.4 Low-q Form of Retf0 . . . ? . ? . ? . 132 2.5 Simple Reparam etrization of the PH and LR Interactions 134 3.1 Beam Energies for Experiment 268 143 3.2 Apertures used for Experiment 268 145 3.3 Targets for Experiment 268 146 3.4 Comparison of HRS and K600 Specifications 150 5.1 Grid in x101 . . . . . 205 6.1 Energy Levels of 9 Be 229 6.2 Energy Levels of 16 0 230 6.3 Energy Levels of 16 0 (cont .) 231 6.4 Energy Levels of 4?Ca . . . 232 6.5 Overall Normalization Factors for Experiment 268 . 244 7 .1 Empirical Effective Interactions (100 Me V) 297 7.2 Empirical Effective Interactions (200 MeV) 307 7.3 Empirical Effective Interactions (318 MeV) 320 7.4 Empirical Effective Interact ions (500 l\.IeV ) 332 7.5 Empirical Interaction with P erey Effect (1 6 0 , lfl() MeV ) . 34J 7.6 Empirical Interaction with P erey Effect (1 6 0 , 200 MeV) . 341 7.7 Fit to Elastic and Inelastic Data. (1 6 0 , 100 MeV) 344 IX 7.8 Fit to Elastic and Inelastic Data (1 6 0, 200 Me V) . 344 7.9 Interaction Parameters for Various Energies . 384 A.I Expansion Coefficients for Pg and Ptr (1 6 0) . 403 A.2 Expansion Coefficients for pg and Ptr (4?Ca.) . 404 C.1 Polynomials for 0tgt and o from RAYTRACE . 416 D.1 Interaction Grid: 160 (200 MeV ) . 423 D.2 Interaction Grid: 4?Ca (200 MeV) . 424 D.3 Interaction Grid: 160 (318 MeV) . 425 D .4 Interaction Grid: 160 (500 MeV) . 426 E .1 a) BeO Runs (100 MeV) . . . . . 428 E .1 b) BeO Runs (100 MeV, cont.) . 429 E .2 a) 4?Ca Runs (100 MeV) . . . . . 430 E.2 b) 4?Ca Runs (100 MeV, cont.) . 431 E.2 c) 4?Ca Runs (100 MeV, cont.). . 432 E.2 d) 4?Ca Runs (100 MeV, cont.) . 433 E.2 e) 4?Ca Runs (100 MeV, cont.). . 434 E.3 a) BeO Runs (200 MeV) ... . . 435 E .3 b) BeO Runs (200 MeV , cont.) . 436 E .3 c) BeO Runs (200 MeV , cont.). . 437 E .4 a) 4?Ca Runs (200 MeV) .... . 438 E.4 b) 4?Ca. Runs (200 MeV, cont.) 439 E.4 c) 4?Ca Runs (200 MeV, cont .) . . 440 F .1 a) 9 Be(p,p)3/21 (elastic) ; Er = 100 MeV . . 442 F.1 b) 9 Be(p, p')l / 2T ( 1.680 Me V) ... . . .. . 443 X F.l c) 9 Be(p,p')5 / 21 (2.429 MeV ) . 444 F.1 d) 9 Be(p,p')l / 21 (2 .78 MeV). . 445 F .1 e) 9 Be(p,p')5 / 2't (3 .049 MeV) . 446 F.1 f) 9 Be(f, p')3 / 2?t (4 .704 MeV) . 447 F .1 g) 9Be(p,p') Lor (6 .5 MeV) . . . 448 F .2 a ) 16O(p,p)0i (elastic) ; Ep = 100 MeV . 449 F.2 b) 16O(p,p')0f (6 .0494 MeV). . 450 F.2 c) 16O(p, p')31 (6 .1299 MeV ) . . 45 ] F.2 d) 16O(p, p')2i (6.9171 MeV) . . 452 F .2 e) 16 O(p,p')l1 (7 .1169 MeV) . . 453 F .2 f) 16 O(p,p')21 (8.8719 MeV) . . 454 F .2 g) 16 O(p, p')l2 (9 .585 MeV ) . 455 F.2 h) 16O(p, p')2f (9 .8445 MeV). . 456 F.2 i) 16O(f, p')4?t (10.356 MeV) . 457 F .2 j) 16 O(p,p')01 (10 .957 MeV) . 458 F .2 k) 16 O(.r, p')4t (11.097 MeV) . . 459 F .2 1) 16O(.r, p')2t (11.520 MeV) . . 460 F.2 rn) 16 O(.r, p')0t (12.049 MeV) . 461 F .2 n) 16O(f,p')l3 (12.440 MeV ) . . 462 F.2 o) 16O(p, p')22 (12 .530 MeV). . 463 F.2 p) 16 O(p, p')02 (12 .796 MeV) . . 46cl F .2 q) 16 O(p, p')23 (12.969 MeV ) . . 465 F.2 r) 16 O(p,p')l3 .08 (13 .08 Me\/) . 466 F .2 s) 16O(p, p')34 (1 3 .259 Me V) . . 467 Xl F.3 a) 4?Ca(p,p)0t (elast ic) ; Ep = 100 MeV . 469 F .3 b) 4?Ca(p,p')0t (3 .3521 MeV ) . 470 F.3 c) 4?Ca(p,p')31 (3 .7364 MeV) . 471 F .3 cl) 4?Ca(p,p')2t (3 .9041 MeV) . 472 F .3 e) 4?Ca(p, p')51 (4.4915 MeV ) . 473 F .3 f) 4?Ca(p, p')0f (5.213 MeV) . . . 474 F.3 g) 4?Ca(p,p')2t (5 .249 MeV) . . 475 F .3 h) 4?Ca(p, p' )4t (5.279 MeV) . . 476 F .3 i) 4?Ca(p, p' )41 (5 .6143 Me V) . 477 F.3 j) 4?Ca(p,p')2t (5 .6301 MeV) . 478 F .3 k) 4?Ca(p, p' )l1 (5 .9033 MeV) . 479 F .3 l) 4?Ca(p,p')6.028 (6.028 MeV) . 480 F.3 m) 4?Ca(p,p')32 (6 .2858 MeV) . . 481 F.3 n) 4?Ca(p, p')4t (6.5084 MeV) . 482 F .3 o) 4?Ca(p,p' )4t (6 .5436 MeV) . 483 F.3 p) 4?Ca(p, p')33 (6 .5833 Me V) . 484 F.3 q) 4?Ca(p,p' )22 (6.7509 MeV) . 485 F.3 r) 4?Ca(p, p' )6.909 (6 .909 MeV) . .. .. . 486 F .3 s) 4?Ca(p, p')6 .931 (6.931 MeV) . 487 F .3 t) 4?Ca(p,p' )12 (6 .951 MeV) . . 488 F .3 u) 4?Ca(p, p')7 .11 (7 .11 MeV) ? 1l8D F.4 a) 9 Be(p,p)3 / 21 (elastic) ; Ep = 200 MeV . . 49 1 F.4 b) 9 Be(p, p')l / 2i (1.680 MeV ) . 492 F.4 c) 9 Be(p, p')5 / 21 (2.429 MeV) . 493 Xll F.4 d) 9 Be(p,p')l/21 (2.78 MeV). . 494 F.4 e) 9 Be(p, p')5 /2i (3 .049 MeV) . 495 F .4 f) 9 Be(p,p')3 / 2i (4.704 MeV) . 496 F.4 g) 9 Be(p,p') Lor (6 .5 MeV) . . . 497 F .5 a) 16 O(p,p)0i (elastic); Er = 200 MeV . . 498 F .5 b) 16O(p,p')0t (6 .0494 MeV) . - . 499 F.5 c) 16 O(p, p')31 (6.1299 MeV) .. . 500 F .5 d) 16 O(p, p' )2 i (6 .9171 MeV). . 501 F .5 e) 16 O(p, p')l1 (7 .1169 MeV) . . 502 F.5 f) 16O(p, p')21 (8 .8719 MeV) .. . 503 F.5 g) 16O(p,p' )12 (9.585 MeV) .. . 504 F.5 h) 16O(p, p' )2t (9 .8445 Me V) .. . 505 F.5 i) 16O(p,p')4i (10 .356 MeV) . 506 F .5 j) 16 O(p, p')01 (10 .957 MeV ) . 507 F.5 k) 16 O(p, p')4t (11.097 MeV ) . . . 508 F.5 1) 16O(p, p')2f (11 .520 MeV) . . . 509 F .5 m) 16 O(p, p')0f (12.049 MeV ) . 510 F .5 n) 16O(p, p' )13 (12.440 MeV ) . . 511 F.5 o) 16 O(p, p')22 (1 2 .530 Me V) . . 512 F .5 p) 16O(p,p')02 (12 .796 MeV). . 513 F .5 q) 16O(p, p')23 (12 .969 MeV) . . 5 1-1 F.5 r) 16 O(p', p')l3 .08 (13 .08 MeV) . 515 F.5 s) 16O(p,p')3i (13 .259 MeV) . . 516 F.5 t) 16O(p,p')l i (13.664 MeV) . . 517 ... Xlll F.5 u) 16 O(p, p')4f ( 13.869 Me V) . . . 518 F .5 v) 16 O(f,p')25 (13.98 MeV) . 519 F .5 w) 16O(f, p')0t ( 14.032 Me V) . 520 F .5 x) 16 O(p, p')41 (14 .302 MeV) . . 521 F .5 y) 16 O(p, p')5i ( 14.399 Me V) .... . 522 F.6 a) 4?Ca(p,p)0i (elastic); Ep = 200 MeV . 524 F.6 b) 4?Ca(f, p')0 f (3.3521 MeV) . 525 F.6 c) 4?Ca(p, p')31 (3. 7364 Me V) . 526 F.6 d) 4?Ca(f,p')2?t (2.9041 MeV) . 527 F.6 e) 4?Ca(p,p')51 (4 .4915 MeV) . 528 F.6 f) 4?Ca(f, p')0f (5 .213 MeV) . . 529 F .6 g) 4?Ca(f, p')2t (5 .249 MeV) . . 530 F.6 h) 4?Ca(f, p')4 ?t (5.279 MeV) . . 531 F.6 i) 4?Ca(f, p')41 (5 .6143 MeV ) . 532 F.6 j) 4?Ca(f, p')2f (5 .6301 MeV ) . 533 F.6 k) 4?Ca(p, p')l1 (5 .9033 MeV ) . 534 F .6 1) 4?Ca(f,p')6 .028 (6.028 MeV ) . 535 F .6 m) 4?Ca(p, p')32 (6 .2858 MeV) . . 536 F .6 n) 4?Ca(p, p')4t (6.5084 MeV ) . 537 F.6 o) 4?Ca(p, p')4f (6 .5436 MeV) . 538 F.6 p) 4?Ca(p, p')33 (6 .5833 MeV) . 53D F.6 q) 4?Ca.(p, p')22 (6 .7509 MeV) . 54() F.6 r) 4?Ca.(p,p')6 .909 (6 .909 MeV) . 54 1 F .6 s) 4?Ca.(p, p')6 .931 (6 .931 Me\!) . 542 XlV F.6 t) 4?Ca(p,p')l2 (6.951 MeV ) . . 543 F.6 u) 4?Ca(p, p')7 .ll (7.11 MeV) . 544 xv List of Figures 1..1 Interior Sensitivity of Nucleon Inelastic Scattering 3 1.2 Shell Structure of 160 and 4?Ca . . . . . . . . . . 6 2.1 Comparison of PH , NL and FL t-Matrices (100 MeV) 33 2.2 Comparison of PH, NL and FL t-Matrices (200 MeV ) 34 2.3 Comparison of PH, NL and FL t-Matrices (318 MeV) 35 2.4 NRIA Calculations for er(q) and Ay (1 6 0, 100 MeV) . 40 2.5 NRIA Calculations for er(q) and A 411 ( ?Ca, 100 MeV) 41 2.6 NRIA Calculations for cr(q) and Ay (1 60, 200 MeV) . 42 2.7 NRIA Calculations for er( q) and Ay (4?Ca, 200 Me V) 43 2.8 NRIA Calculations for Q (1 6 0 and 4?Ca, 200 MeV) 44 2.9 NRIA Calculations for er(q) and Ay (1 6 0, 318 MeV) 45 2.10 NRIA Calculations for er( q) and Ay (4?Ca, 318 Me V) 46 2 .11 NRIA Calculations for Q (4?Ca, 318 MeV) 47 2.12 LDA Optical Potentials (1 6 0, 100 MeV) 69 2.13 LDA Optical Potentials (4?Ca, 100 MeV) 70 2.14 LDA Optical Potentials (1 6 0, 200 MeV ) 71 2.15 LDA Optical Potentials (4?Ca, 200 MeV) 72 2.16 LDA Optical Potentials (1 6 0 , 318 MeV ) 73 2.17 LDA Optical Potentials (4?Ca. , 318 MeV) 7,1 2.18 LDA Calculations for er(q) and A 611 (1 0 , ]()() MeV) 78 2.19 LDA Calculations for er(q) and Ay (4?Ca. , 100 MeV) 79 2.20 LDA Calculations for er(q) and Ay (1 6 0 , 200 MeV) 80 XVl 2.21 LDA Calculations for a-(q) and Ay (4?Ca, 200 MeV) 81 2.22 LDA Calculations for Q (1 6 0 and 4?Ca, 200 MeV ) . 82 2.23 LDA Calculations for a-(q) and Ay (1 6 0, 318 MeV) 83 2.24 LDA Calculations for a-(q) and Ay (4?Ca, 318 MeV) 84 2.25 LDA Calculations for Q (4?Ca, 318 MeV) . 85 2.26 Z-Graph for Scattering of a Dirac Particle 92 2.27 IA2 , LDA , NP, and NRIA Optical Potentials (1 6 0 , 200 MeV ) . 97 2.28 IA2 , LDA , NP, and NRJA Opt;caJ P otenUa!s ("Ca, 200 MeV) 98 2.29 IA2, LDA, NP, and NRIA Optical Potentials (1 6 0, 318 MeV ) . 99 2.30 IA2 , LDA , NP, and NRIA Opbcal Potentials ("Ca, 318 MeV) JOO 2.31 Elastic Scattering with IA2 , LDA , NP, and NRIA Potenti als (200 MeV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 2.32 Elastic Scattering with IA2 , LDA , NP, and NRIA Potential s (318 MeV) ...... ... .. . .... . . . 103 2.33 CV Estimate of the Pauli Blocking Factor . 116 2.34 Reparametrization of the PH Interaction ( 100 Me V) . . 122 2.35 Reparametrization of th e PH Interaction (200 MeV) . . 123 2.36 Reparametrization of the PH Interaction (318 MeV ) . . 124 2.37 Reparametrization of the NL Interaction ( 100 Me V) . . 125 2.38 Reparametrization of the NL Interaction (200 IVle V) . 126 2.39 Reparametriza.tion of the NL Interacti on (318 l\ leV) 127 2.40 Repararn etriza.tion of the LR Interaction (21l0 l\ leV) . 128 2.41 Reparametrization of the LR Interaction (318 MeV) . 129 2.42 Reparametrization of the LR Interac tion ( 500 Me V) . 130 XVll 3. 1 IU CF Cyclotron Floor P lan 142 3.2 K600 Spect rometer .. 148 3. 3 Sein tilla tor Electronics 154 3.4 Wiring of LRS 2735b P rinted Board . 156 3.5 V DC Logic Circuit 158 3.6 Coincidence Circuit 159 3. 7 Electroni cs for Integrators and BL 2 . 161 4. 1 Kinematic Defocusing . . . . . . . . . 167 4 .2 Kinematic Defocusing and Dispersion Matching 169 4 .3 Kinemati c Factor for 160 and 4?Ca .. .. . 175 4.4 Scattering Angle Offset- Cross Plot Method 177 4.5 Angle Offset / Integrator Asymmetry (January 1987) 182 4. 6 Angle Offset / Integrator Asymmetry (April 1987) 183 4. 7 Beam P olarizations in Janu aryand April 1987 186 4.8 Beam P olarizations in January and March 1988 187 5.1 T ypical Drift Time Spectrum . . ... 194 5.2 Drift Table- Graphical Representation 197 5.3 Extremum Rays for n-Hit Events 199 5.4 Efficiency and 2-Hit Events 206 5.5 P osition and Angle for Various Event T ypes 208 5.6 2-Hit Recovery- One-Plane Slope Metl10d 212 5. 7 Calculated dM 1 (00110) Drift Length 213 5.8 Diagnostics- Hot Wire . 219 5.9 Diagnosti cs- Cross Talk 220 XVJil 6.1 Background due to Beam Halo ...... . ... .. . . . . . . 224 6.2 0tgt-Spectrum for Run with Beam Halo and Sli t Scat tering . . 225 6.3 Background due to Slit Scattering . 226 6.4 Fitted BeO Spectrum . 235 6.5 Fitted 4?Ca Spectrum . . 236 6.6 Histograms of Fitted Peak Widths . . 250 6. 7 Comparison with Previous 200 Me V Elastic Measurements . 251 6.8 9 Be(p, p')3 / 21, 1/ 2t, and 5/21 (Ep = 100 MeV) . . 254 6.9 9 Be(p, p')l / 21, 5/ 2t , and 3/ 2t (Ep = 100 MeV) . . 255 6.10 9 Be(p, p')Lor (Ep = 100 Me V) .. .. . 256 6.11 16O(p,p')0t, ot, 31 (Ep = 100 MeV) . 257 6.12 16O(p, p' )2t , 11, 21 (Ep = 100 Me V) . 258 6.13 16 O(p, p')l 2, 2i, 4i (Ep = 100 MeV) 259 6.14 16 0(p, p')01, 4i , 2f (Ep = 100 Me V) 260 6.15 16 0(p, p' )0t, 13, 22 (Ep = 100 Me V) 261 6.16 16 0(p,p' )02, 23, 13 .08 (Ep = 100 MeV) . 262 6.17 160(p,p' )34 (Ep = 100 MeV) . .. . . 263 6.18 4?Ca(p,p')0t , 0t, 31 (Ep = 100 MeV) 264 6.19 4?Ca(p, p' )2t , 51, Of (Ep = 100 Me V) 265 6.20 4?Ca(p, p' )2i , 4t, 41 (Ep = 100 MeV ) 266 6.21 4?Ca(p, p' )2f, 11, 6.028 (Ep = 100 MeV) 267 6.22 4?Ca(p, p')32, 4f, 4f (Ep = 100 Me V) . 268 6.23 4?Ca(p, p')33, 22, 6.909 (Ep = 100 MeV) 269 6.24 4?Ca(p, p' )6 .931 , 12, 7.11 (Ep = 100 MeV) 270 XIX 6 .25 9 Be(p, p')3 /21, 1/2t, and 5/ 21 (Ep = 200 MeV) . . 271 6.26 9 Be(p, p')l /21, 5/ 2t, and 3/ 2t (Ep = 200 MeV) . . 272 6.27 9 Be(p, p')Lor (Ep = 200 MeV) .. . . . 273 6.28 16 O(p, p')0t, 0t, 31 (Ep = 200 Me V) . 274 6.29 16 O(.P, p')2i, 11, 21 (Ep = 200 Me V) . 275 6.30 16 0(p, p')l2, 2t, 4t (Ep = 200 MeV) . 276 6.31 16 O(p, p')01, 4t, 2f (Ep = 200 MeV) . 277 6.32 16 O(p, p')0t, 13, 22 (Ep = 200 Me V) . 278 6.33 16 O(p,p')02, 23, 13 .08 (Ep = 200 MeV) . . 279 6.34 16 O(p, p')34, It, 4f (Ep = 200 MeV) . 280 6.35 16 O(p,p')25 , ot, 41 (Ep = 200 MeV ) . 281 6.36 16 0(p,p')5t (EP = 200 MeV) .... . 282 6.37 4?Ca(p, p')0t , ot, 31 (Ep = 200 MeV) . 283 6.38 4?Ca(p,p')2t, 51, Of (Ep = 200 MeV) . 284 6.39 4?Ca(p,p')2t, 4i, 41 (Ep = 200 MeV) . 285 6.40 4?Ca(p,p')2f, 11, 6.028 (EP = 200 MeV ) . 286 6.41 4?Ca(p, p')32, 4t, 4! (Ep = 200 MeV ) . . 287 6.42 4?Ca(p, p')33, 22, 6.909 (Ep = 200 Me V) . 288 6.43 4?Ca(p, p')6 .931, 12, 7.11 (Ep = 200 MeV) . 289 7.1 Comparison of EMP(1 6 O) and PH Interactions (100 MeV) . 298 7.2 EMP Calculations for 16 0 31, 2?t , and 11 (lll0 l\,JeV) . 299 7.3 EMP Calculations for 16 0 4;, 2j , and Oj (100 l\ leV) . 30(1 7.4 EMP Calculations for 4?Ca. ot, 31, and 2{ (100 MeV) . . 301 7.5 EMP Calculations for 4?Ca 51, 32, and 33 (100 MeV) . . 302 xx 7.6 EMP Elastic Calculations for 16 0 and 4?Ca ( 100 Me V ) . 303 7.7 EMP Optical Potenti als (1 6 0 , 100 MeV) 304 7.8 EMP Opti cal Potentials (4?Ca, 100 MeV) . 305 7.9 Comparison of EMP(1 6 0) and PH Interactions (200 MeV) 308 7.10 Comparison of EMP(1 6 0) and LR Interactions (200 MeV) . 309 7.11 EMP Calculations for 160 31, 21", and 11 (200 MeV) . 31 0 7.12 EMP Calculations for 160 41", 2j , and ot (200 Me V) 311 7.13 EMP Calculations for 4?Ca. Of , 31, and 21" (200 Me V) . 31 2 7.14 EMP Calculations for 4?Ca 51, 32, and 33 (200 Me V) . . 313 7.15 EMP Elastic Calculations for 16 0 and 4?Ca (200 Me V) . 314 7.16 EMP Optical Potentials (1 6 0 , 200 MeV) 31 5 7.17 EMP Optical Potenti als (4?Ca , 200 Me V) . . 316 7.18 Comparison of EMP(1 6 0) and LR Interactions (318 MeV) . 321 7.19 Comparison of EMP(1 60) and PH Interactions (318 MeV) . 322 7.20 EMP Calculations for 160 31, 2t? , and 11 (318 MeV) . 323 7.21 EMP Calcula tions for 160 4t? , 2j , and 0j (318 Me V) . 324 7.22 EMP Calculations for 4?Ca Of , 31, and 21" (318 MeV) . 325 7.23 EMP Calculations for 4?Ca 51, 32, and 33 (318 MeV) . 326 7.24 EMP Elastic Calculations for 16 0 and 4?Ca (318 MeV) . 327 7.25 EMP Optical Potentials (1 60, 318 MeV) 328 7.26 EMP Optical Potentials (4?Cn, 318 MeV) . '.32D 7.27 EMP Elasti c Calculations fo r 16 0 and 4?Ca. (50 (1 MeV) . 333 7.28 EMP,IA2 , LDA , and NRIA Opti cal Potentials (1 60 , 500 MeV) 334 7.29 EMP,IA2 , LDA , and NRIA Optical Potentials (4?Ca. , 500 MeV )335 XX! 7.30 E nergy Dependence of the Interior Sensitivity- 16 0 31 337 7.31 Energy Dependence of the Interior Sensitivity- 16 0 11 338 7.32 Fit to 100 MeV 16 0 Elastic and Inelastic Data (I) . 345 7.33 Fit to 100 MeV 16 0 Elastic and Inelastic Data (II) 346 7.34 Fit to 100 MeV 16 0 Elastic and Inelastic Data (III) 347 7.35 Fit to 200 MeV 16 0 Elastic and Inelastic Data (I) . 348 7.36 Fit to 200 MeV 16 0 Elastic and Inelas tic Data (II) 349 7 .37 Fit to 200 Me V 16 0 Elastic and Inelastic Data (III) 350 7.38 A Dependence of the Effective Interaction (1 60, 100 MeV , I) 352 7.39 A Dependence of the Effective Interaction (1 60, 100 MeV , II) 353 7.40 A Dependence of the Effective Interaction (4?Ca, 100 Me V, I) 354 7.41 A Dependence of the Effective Interaction (4?Ca., 100 MeV, II) 355 7.42 A Dependence of the Effective Interaction (16 0 , 4?Ca., 100 MeV)356 7.43 A Dependence of the Effective Interact ion (1 6 0 , 200 MeV, I) . 357 7.44 A Dependence of the Effective Interaction (1 6 0 , 200 MeV, II) 358 7.45 A Dependence of the Effective Interaction (4?Ca, 200 MeV , I) 359 7.46 A Dependence of the Effective Interaction (4?Ca, 200 MeV , II) 360 7.47 A Dependence of the Effective Interaction (1 6 0 , 4?Ca., 200 MeV)361 7.48 A Dependence of the Effective Interaction (1 6 0 , 318 MeV, I) . 362 7.49 A Dependence of the Effective Interaction (1 6 0 , 318 MeV, II) 363 7.50 A Dependence of the Effective Interaction (4?C;i , 318 Me V, I ) 364 7 .51 A Dependence of the Effective Interaction (4?C;:i , 3J 8 Mc V, I I) 365 7.52 A Dependence of the Effective Interaction (16 0 , 4?Co , 318 MeV)366 XXll 7.53 Elastic Scattering with EMP, IA2, NP, and NRIA Potentials (200 MeV ) .... . .... . . .... .............. 371 7.54 Elastic Scattering with EMP, IA2 , NP, and NRIA Potentials (318 MeV ) ... ....... .... .. .......... . .. 372 7.55 EMP, IA2, NP, and NRIA Optical Potentials (1 6 0, 200 MeV) 373 7.56 EMP, IA2 , NP, and NRIA Optical Potentials (4?Ca, 200 MeV ) 374 7.57 EMP, IA2 , NP, and NRIA Optical Potentials (1 6 0 , 318 MeV) 375 7.58 EMP, IA2 , NP, and NRIA Optical Potentials (4?Ca, 318 MeV) 376 7.59 Comparison to Dirac Phenomenology (a-/ o-R , A 11 ) 377 7.60 Comparison to Dirac Phenomenology (Q) . . . .. 378 7.61 EMP( 4?Ca) , EMP(1 6 0) , and DP Optical Potentials for 4?Ca (100 MeV ) . . . . ......... . ... . .. . . .... ... 379 7.62 EMP( 4?Ca), EMP(1 60) , and DP Optical Potentials for 4?Ca (200 Me V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380 7.63 EMP( 4?Ca), EMP(1 6 0) , and DP Optical Potentials for 4?Ca (318 MeV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381 7.64 Comparison of EMP(1 6 0) , PH, and LR Interact ions (Retf0 ) 385 7.65 Comparison of EMP(1 6 0), PH , and LR Interactions (Imtf0 ) 386 7.66 Comparison of EMP(160) , PH, and LR Interactions (Ret&'5 ) 387 7.67 Energy Dependence of th e Empirical Intera.ct io11 388 7.68 Difference of the PH and ], Lt-Ma.tri ces 389 A.1 Ground State Charge Densiti es for 160 and 4?Ca . 405 A.2 Transition Charge Densities for 160 . 406 A.3 Transition Charge Densities for 4?Ca . 407 XXlll B .1 Kinematics of an Inelastic Binary Reaction . 410 B.2 Differential Recoil for 100 and 200 Me V Kinematics 411 C.1 Design K600 Medium Dispersion Focal Plane . 417 C.2 Effect of the K-Coil on the Focal Plane 418 C.3 Effect of the K-Coil on Nuclear Lines in x f 0f . 419 C.4 Effect of the H-Coil on the Focal Plane 420 C.5 Effect of the H-Coil on Nuclear Lines in x 10 f . 421 XXJV 1 Introduction Studies of the projectile-nucleon effective interaction in the nuclear me- dium and of the internal structure of nuclei are among the dominant themes of intermediate energy nuclear physics. Electron scattering for a long time has been an extrem ely popular tool for nuclear structure studies. The electroex- citation of discrete nuclear transitions can be described as a direct reaction which is driven by a local two-body interaction. We believe that both the reaction mechanism and the effective interaction are understood accurately. Together with the fact that nuclei are essentially transparent to high energy electrons , this permits us to extract the relevant aspects of the structure of the nucleus with very high precision . Since electromagnetic probes a.re sensitive to several one-body target densities, including charge, spin, cur- rent, and spin-current degrees of freedoms , a wealth of important st ru ct ural information on nuclei can be obtained [Pet 81]. In spite of all these advantages, the versatility of the electron as a nuclear probe is limited . Electrons are largely insensitive to the bulk neu- tron distribution and view neutrons almost exclusively through the magneti c m oment of a single unpaired valence neutron. Hadronic projectiles, on the other hand , are about equally sensitive to neutrons and to protons . They also sample transition densities which are not accessible to elec t ron scatter- ing at all. Direct o+ - o- transitions are examples of a type of tra.11 sitio11 which is forbidden in first order for electron scattering [DeF 66], which a.re however readily excited by proton scattering through th e longitudinal spin 1 response [Lov 83]. Therefore, a truly comprehensive investigation of all the one-body aspects of nuclear structure requires the inclusion of a complemen- tary analysis of hadron scattering . To make hadrons a quantitative probe for nuclear structure , however , we must understand or at least calibrate the rele- vant aspects of the reaction mechanism and of the projectile-nucleus effective interaction . Of the hadronic interactions, the nucleon-nucleon interaction is the one which has the most sound theoretical foundation . Furthermore, there is a roughly 300 Me V wide "window of visibility" within which the interior sen - sitivity for nucleons becomes quite comparable to that of electrons . The good interior sensitivity is primarily due to the fact that the isosca.la.r pa.rt of the dominant matter interaction , which drives distortion effects , passes through a broad minimum between about 200 and 500 MeV [Car 85] . Also, at these energies the wavelength of the probe is short which provides for excellent radial resolution . Finally, in this region multistep processes are at a minimum which allows us to assume that direct , one-step excitations are the dominant reaction mechanism . The sensitivity of protons to the nuclear interior and the energy dependence of this sensitivity has been studied for the lowest lying m onopole transition in 4?Ca for energies between 60 and 800 Me V with pseudodata [Kel 88] . The results of the pseudodata analysis a re shown in Figure 1. 1. Even though absorption in creases steadil y th rough- out this energy range the interior sensitivity improves dramati cally between 60 and about 200 MeV . The improving sensitivity is due to the decreasing importance of Pauli blocking in the nuclear interior . This causes the con- 2 2 0 - 2 - 4 4 ....--.. 4?Ca (p ,p) o; ?Ca(p,p)o; r<) I - 6 EP = 60MeV EP = 400MeV E 4- - 8 r<) 2 I 0 ---- 0 >, - 2 -+- . (/) C - 4 4 4 (1) ?Ca (p ,p )o; ?Ca(p ,p)o; 0 - 6 EP = 1 00MeV EP = 51 SMeV C - 8 0 2 -+- (/) 0 C 0 ~ -2 - 4 4 4C ?Ca(p ,p)o; ?Ca (p ,p) o; 0 L - 6 EP = 150MeV EP = 650MeV -+- ::) (1) - 8 z 2 0 - 2 - 4 4 4?Ca(p,p)o; ?Ca (p ,p) o; - 6 EP 200MeV EP = 800MeV - 8 0 2 4 6 8 0 2 4 6 8 r (f m) r (f m) Figure 1.1: Energy dependence of the interior sensitivity of nucleon inelas- tic scattering; the window of maximum transparency is between about 200 and 500 MeV. The figure shows the results of a pseudodat a analysis fo r the ot state of 4?Ca [Kel 88]. 3 tribution of the interior to increase relative to that of t he surface, thereby improving the interior sensitivity. T he sensitivity is op timal between about 200 and 500 Me V since in this energy region declining density dependence and increasing absorption balance. At higher energies absorp tion becomes dominant and because of the decreasing penetrability, the interior sensitvity deteriorates. Direct , one-step reactions can be conveniently treated within the single- scattering framework by means of a local "tp" folding model, where the scat - t ering amplitude is constructed from the effe ctive nucleon-nucleon interaction weighted by the nucleon distribution inside the target nucleus . Within this m odel, knowledge of either the interaction fact or t or the stucture factor p permits the systematic evaluation of the unknown fact or. In practice, the comple te amplitude for a certain transition contains not only an implied sum over charge indices, but may additionally involve a whole variety of differ- ent densities and interaction components. The first problem can be ignored for the case of self-conjugate nuclei where transitions are purely isoscalar or isovector in character. Furthermore, for a few special classes of transitions the number of relevant tp terms can effectively be reduced . The mos t import ant class of transitions is comprised of natural parity transitions (61r = (- )t.J with 61r = 1ri1rJ) to low-lying collective states in the t arget nucleus. Not only is the matter density for this type of transition much larger th an eith er spin , current , or spin-current densiti es, in addition the matter interaction also dominates over the other interaction components [Car 85]. In proton scattering , the excitation of natural parity states is driven exclusively by 4 t he spin-indep endent central and spin-orbit components of the interact ion. For n a tural parity t ransitions, therefore , we will be able to study these two components of the nucleon-nucleus interaction, since both the reac tion mech- anism is reason ably well known and all the relevant nuclear structure aspects can be reliably determined by independent means such as electron scattering. The self-conjugate nuclei 160 and 4?Ca are the ideal laboratory for effec- tive interaction studies. Both nuclei have doubly closed shells (see Figure 1.2 ) and their spectra contain many strong well separated low-lying collecti ve sta tes fo r which also comprehensive elect ron scattering data are available [But 86 , Mis83 , Har 84] . Some of these states are surface excitations, such as the 31 states , and are sensiti ve to t he low-density apects of the effecti ve interaction . Other states, such as the inelasti c monopole transitions or the 11 st at e of 16 0 , peak in the interior and thus probe the high-density pro per- ti es of the effective interaction . Intermediate cases like the 32 state of 4?Ca, which has strong lobes of the transition density both in the interior and at the surface, will provide interesting challenges for any effective interaction . Finally, we find in these t argets states which give insights into different reac- tion mechanisms , such as the 2f state of 160 which is a good candidate for a two-step excitation . For some states, such as the Of state in 16 0 , densiti es other the matter density might become import ant fo r cert ain energies and m omentum transfers [P et 85] . The quality of t heoretical interact ions and their usefulness in quanti - t a tive studies of nuclear structure can be easily tes ted on the isosca.l a. r nat - ural parity states of these targets . Unsuccessful nonrelati visti c impulse ap- 5 ....., ....., ,...... N 0 .0...0.. .... .. .N... .. ,-... ,-... ,-... N ,-... ,-... ,-... .N._ , .'.d_", ._ , .'< N ._:j", .._, ."._?, ~ JJ p.tj,, p.~ .. t.i...) .J, ..... ..... ..... N.,... a; 0 ::c: ~ u 3 ? p?? gure 1.2: Shell structure of the doubly magi.c self-conjugate nuclei "O and Ca for protons (or neutrons)? On the Je[t are the harmonic oscillato r levels40, to the right the actual )evels including the spin-orbit splitting. The '.'umbers in parentheses are the occupation numbers for the level, the numbers m brackets the sum of all particles up to and including the level 6 proximation calculations, especially for interior-peaked states ( e.g. [Kel 82]), suggested the necessity of strong medium modifications to the effective in- teraction. The strongest density dependence is exhibited by the central spin- independent isoscalar component. Pauli blocking manifests itself as damp- ing of the imaginary part , while short-range correlations modify the real part of the central component by adding a short-range repulsive contribution which is proportional to density. All of the available theoretical models pro- duce medium modifications which are qualitatively similar [Ger 79, Ger 83, Rik 84 , Nak 88, Ray 90]. However , their predictions of scattering data differ significantly [Kel 89a] . Unfortunately, however, the various models do not only use different nucleon-nucleon potentials but also use different numerical procedures and approximations to calculate the effective interactions . Ad- ditionally, all the interactions are given in the form of enormous tables of amplitudes or tables of Yukawa expansion coefficients in different rep resen- tations which do not allow much insight into the physics of the respective model. A comparison of one model to others based on these interaction tables is therefore extremely difficult, if not altogether impossible. The interactions presently available have been found not to be suffi - ciently accurate for detailed nuclear structure applications [Kel 86c], raising th e ques tion whether this problem is due to defici encies of th e interaction or due to the local density prescription [J eu 74, J eu 76] whi ch is used to app ly th e effec tive interaction to nucleon-nucleus scattering. The prescripti on as- sumes that the knowledge of only the local density of th e medium in which the particular reaction takes place is sufficient to evaluate project il e-nucleus 7 scattering. Within this framework it should not matter whether the inter- act ion takes place in the interior or at the surface of the nucleus ; it should also not matter whether the reaction occurs in a small or a large nucleus . Although physically plausible, this prescription has never been established as an actual approximation to a m ore accurate theory whose corrections can, even in principle, be evaluated . Presently, the local density prescription 1s more of a convenient ansatz than an act ual approximation . In an alternate approach, we use a physically motivated phenomenology which can serve both as a means to compare theoretical models to each oth er, as well as a means to describe data [Kel 85a]. The effective interaction which emerges from such a. fit to data can then be considered a measured interaction for a finite nuclear system. A comparison to parameters which were obtained from a fit to theory will help assess differences and /or deficiencies of the theoretical model. Finally, we will have a means to assess the validity of the local density hypothesis in a consistent and more or less model independent fashion by systematically studying the dependence of the interaction on the local density, the target, and the energy. These studies, therefore, are the major goal of the present work , in which we will systematically address all the major premises of the local density prescription . * * * In Chapter 2 an attempt is made to rev iew more or less ca.rcfu ll y and completely all the theoretical background which is relevant fo r thi s work , including the relativistic impulse approximation and th e more recent full - folding calculations . We present in this chapter various IA and LDA calcula- 8 tions, as well as IA2 calculations, and compare them with our new 160 and 4oc a data at 100, 200 and 318 Me V. Also, in this diapter we introduce the tools wl1ich will be used for our phenomenological analysis . Chapter 3 deals primarily witl1 the experimental setup, including the accelerator, t11e beam line optics, t11e apertures and targets used, tlie spec- trometer and focal plane detectors, and t11e electronics and data acquisition . Chapter 4 explains the necessary calibrations for our experiment . Some of these calibrations were done on-line during tl1e experiment, sucl1 as vertical scans and the matching of the spatial and angular dispersion; otl1ers were done during data analysis based on measurements taken during the exper- iment . This includes the determination of t11e beam polarization, the true scattering angle, and various tests addressing tl1e stability of the cross sec- tions with respect to parameters like acceptance and event rate . Chapter 5 is dedicated to our drift cliamber detectors . Here we discuss the observed event types and the methods used to accurately determine particle trajecto- ries. We also will identify all the global corrections to t11e cross section which are required due to tlie efficiency of the chambers, as well as to certain back- ground modified events which are not processed in the analyzer. Finally, we will mention some of the diagnostics that are available for finding problems 1n the chamber performance. Ch apter 6 deals w1? t 1 tlie data reduction. This includes a discussion 1 of the data replay and the cuts used , as well as a. brief discussion of th e line-shape fitting part of the analysis . Also covered in this chapter are the computation of the unpolarized cross section, the analyzing power, and their g errors, as well as the kinematic formulae which were used to express our results m c.m. quantities . Furthermore, the vanous normalizations that have to be applied to the data are explained . At the end of this chapter we present and discuss our experimental results. In Chapter 7 we show and discuss the res ults of our effective interaction analysis . We will compare the ability of our empirical interaction to accurately predict scattering data with that of the available theories, including some relativistic models . To test the :1 validity of the local density prescription, we will study the dependence of the effective interaction on both the mass number A and the energy E. Finally, in Chapter 8 we will give a brief summary of our conclusions. 10 2 Theoretical Background 2.1 The Transition Matrix as an Effective Interaction To motivate the concept of an effective interaction let us consider an example from elementary scattering theory. The Schrodinger equation for the scattering of a particle of mass ? and energy E by a potential v( r) can be written (E - K)x(r) = v(r)x(r), (2.1) where I{ = - '7 2 /2 ? is the kinetic energy operator1 . A solution of Eq. (2.1) can be obtained succinctly by dividing both sides by ( E - K) 1 X = (2 .2) E - K vx. Proper treatment of the singularity by insertion of an infinitesimal +it: in the denominator and addition of any solution of the homogeneous eq uation (E - K)(r) = 0 (2.3) to satisfy the required boundary conditions, incoming plane waves and out- going spherical waves, yields the formal solution of the Schrodinger equation (2.4) with E+ = E + it:. This is known as Lippmann-Schwinger equation , wh ere Gt(E) is the free-particle Green functi on with outgoing boundary conditions. 1 Alternatively, this problem can also be thought of as the scatter in g of two nucl eons where? is the reduced mass and v is the nucleon-nucleon (NN) potential. 11 The transition amplitude for elastic scattering from an incident momentum k to a final momentum k' is T(k',k) = ((k')/v/x(+) (k) ). (2 .5) If one assumes that the effect of the scattering potential on the incident wave is small, one can replace in the matrix element x(+) by?> and write the transition amplitude in the first Born approximation as .. ,I T(k', k);:::: ((k')/v/(k)). (2.6) It is now useful to introduce the transition matrix t by (2.7) Eq. (2.4) then gives a Lippmann-Schwinger equation fort t = v + vGiit (2.8) and the transition amplitude, Eq. (2.5), can be written as the plane wave matrix element T( k', k) = (?>(k')lt/?>(k )) . (2 .9 ) Thus, the significance of the transition matrix here is that it acts as an effective interaction for which the Born approximation is exact , provided an appropriate t can be found [Sat 83, Kel 85]. This feature will be appli ed later , when we treat the Born approximation as an exact model for sea.tiering to extract an effective interaction . 12 2.2 Elastic Nucleon-Nucleus Scattering- The Opti- cal Model Since its introduction by Feshbach, P orter and Weisskopf [Fes 54] in the 1950s, the nuclear optical model has been a simple and yet powerful tool fo r describing the complex problem of elastic nucleon-nucleus scatter- mg . The name "optical model" comes from the many similarities between nuclear elastic scattering and optical refraction and absorption of light . T he wave describing the incident particle experiences within the range of the nu- clear potential refr action , very much like a light wave entering a medium with different index of refraction 2 . If the potential is not constant but has, for in- st ance, a Woods-Saxon shape, the sca ttering process is comparable to a light wave incident on a crystal ball with a radially variable index of refracti on. The occurence of nuclear reactions due to interactions of the projectile with the target nucleons leads to absorption from the elastic channel. Here the optical analog is the absorption of a light wave in a "clouded" crystal ball [Fes 54] . Absorption increases with increasing incident energy since the prob- ability for interaction with the nucleons in the target becomes larger ; in th e presence of very strong absorption one, therefore, observes cross section an- gular distributions that are similar to those for diffraction of electromagneti c waves by an absorptive "black disk" . To account for both its refracti ve and absorptive feature th e opti cal 2 For exa mple, the index of refraction n for a spuare-well potenti al of depth - Vi i a nd a n incident particle with energy E is simply n = J 1 + Vn/ E. 13 potential has to be complex U(r) = V(r) + iW(r), (2.10) where the imaginary part W of the potential must be negative to allow for particle absorption . Furthermore, the optical potential is composed of a central part (Uc ) and a t erm (UL5 ) which accounts for the spin-orbit coupling3 between target and projectile . We thus have the form :t I ~I (2.11) ,, ,, ,', , where uz ,, , describes Coulomb scattering . r Macroscopically, the real central part of V ( r) usually is assumed to ,. I'" h ave the Woods-Saxon shape V( r) = - V0 f( r ), where the radial fun ction f( r) = [1 + e( r - R, 12 )/aJ- 1 reflects the density distribution of the nucleons4 . For the spin-orbit part one assumes tha t a particle in the inner , flat part of the p otential moves in a homogeneous medium without a center with respect to which an angular momentum could be defined . Therefore, only the nuclear surface should contribute to the real part of the spin-orbit interaction . T hi s radial dependence is phenomenologically oft en described by a Thomas-form, h(r) ~ r - 1 fJf(r) / fJr . It is less straightforward to define a phenomenological form for the imaginary part W of the optical potential. For energies below 3 It is found experimentall y that unpolarized par ticles a re polcir ized by t he scatter in g potential; for polarized particles , one find s a left-right asymmet ry in the angu la r d istribu- t ion of the cross section. 4 For r = R 1; 2 , the density decreases by one ha lf; within the surface thickness l , related to the surface diffuseness a by t = 4.4a, the density decreases from 90% to 10%. 14 about 20 Me V a potential which features predominantly surface absorption has been found adequate , while for higher energies ( above 80 Me V) a poten- tial with volume absorption appears to be more appropriate . Cross section angular distributions, however, have been shown to be not very sensitive to the exact details of the shape of the imaginary potential [May 84] . An important extension to the optical model are coupled channels cal- culations, where certain reaction channels are treated explicitly, rather than being represented by simple absorption. The total wave functi on is expanded with respect to wave functions of the elastic and the prominent inelastic channels and only the remaining reaction channels are treated by simple ab- sorption . The resulting system of coupled differential equations can be solved for certain simple cases, e.g . for collective excitations. On a microscopic level, construction of the optical potential is a more difficult problem due to the complexities of the interplay between target ground-state properties, the effective nucleon-nucleon interaction , and me- dium modifications . The traditional nonrelativistic approaches to the op- tical potential in nucleon-nucleus scattering are the multiple scattering for - malisms of Watson [Wat 53], and of Kerman, McManus and Thaler (KMT) [Ker 59] and the nuclear matter self-energy formalism developed by Hiifner and Mahaux [Hiif 72] . More recently, a relativistic approach was initiated by McNeil, Shepard and Wallace [McN 83]. In the next sections th ese different approaches will be reviewed. 15 2.3 Multiple Scattering Approach 2 .3.1 Introduction In the multiple scattering approach the optical potenti al is t he sum of interactions in which the incident projectile excites the t arget nucleus out of the ground state and does not de-excite it back until the la.st step. T he first order t erm of the potential , the so-called single-scattering term , is a coherent sum of terms representing the scattering of the incident projectile by each i11 - divid ual t arget nucleon . The second order term , called the double-scatterin g term , involves a sum in which the incident projectile scatters sequenti ally from any pair of nucleons . Nucleon-nucleon correlati ons in the nuclear wave r ' functi on are, therefore , represented by this t erm. At intermediate energies the single-scattering term of the optical potential dominates: the excita tion of a single nucleon in a two- body collision with the incident projectile is the m ost likely reaction process due to the short range of the interaction and the high velocity (and associated short transit time through the target nucleus) of the projectile [Wal 87] . The Watson multiple scattering series [Wat 53] for the optical potenti al operator appropriate to the elastic scattering of a projectile (0) from a bound sta te of A particles is A A u = L 'Di + L 'OiQ c +, oj (2.12) i = l j -j: i Here Q is th~ (A + 1)-particle projection operator onto the complete, anti - 16 symmetric space of the t arget nucleons with exception of the ground state5 and Q+ is the propagator with outgoing boundary conditions. r{QQ is the asymptotic Hamiltonian projected off the ground state and contains the sum of the projectile kinetic energy operator I<0 and the target Hamiltonian HA (2 .13) The scattering operator r0; is a solution of :i ~I I, ~ I 'I (2 .14) 'I I :, I I ,,, ,, ,,, where v 0 ; is the bare internucleon potential between the incident projectile and the ith target nucleon . r In the single-scattering approximation , the first t erm of the scatter- mg series, Eq . (2.12), yields the momentum-space optical potenti al matrix element ' l'/ A /1 U( k' , k) ~ L (k' ; olro;lk; o )A- (2 .15) i i = l Ii The scattering operator r can be related to the t -matrix , the solution of the ,1 I scattering of two nucleons (see Section 2.1), by (2.16) where (2 . l. 7) 5 Related operators are P which proj ects onto the ground state 1.5 fm - 1 . The Imt?-5 component of the PH interaction resembles very much that of the NL interaction at momentum transfers below 0.5 fm - 1 . Above about 1.5 fm - 1 , on the other hand, the NL interaction much more resembles the FL interaction . The matter interactions begin to differ beyond about 2 fm - 1 , and the analyzing ( powers beyond about 1.2 fm - 1 ,,, . At 200 MeV the Retf0 component of the PH interaction is about 20% stronger12 than the FL interaction and about 30% stronger than the NL interaction at q = 0. At 3 fm - 1 it is twice as strong as the FL interaction and about 50% stronger than the NL interaction. Also, because of a more rapid q dependence it changes sign first. Although at q = 0 the Imtf0 component for PH is about 20% stronger than for NL, the NL component is about 88% stronger than PH at 3 fm - 1 . FL is intermediate between PH and NL . The resulting matter interaction for PH is 25% (35%) stronger than FL (NL) at q = 0 and about 35% (15%) stronger than FL (NL) at q = 3 fm - 1 . For the Ret~5 component the NL and FL interactions are very similar for q < 1 fm - 1 , for Imt~ 5 they are very similar both below 0.5 fm - 1 and agarn 12 The relative strengths which are quoted here are defined as l00(t - t') / t' . 31 above 2 fm - 1 5 . For Ret~ PH is somewhat stronger than the other interactions below 1.5 fm - 1 , but it becomes weaker at large momentum transfers . For the lmt~5 component PH is stronger than the other interactions over the whole momentum transfer region . As for 100 MeV, the FL analyzing power begins to differ from around 1.2 fm - 1 , while PH and NL analyzing powers remain almost equal up to 1. 7 fm - 1 . At q = 3 fm - 1 the FL and NL analyzing powers become again almost equal, but both are more than twice as large as the PH analyzing power . At 318 MeV the Ret~0 component of the PH interaction at q = 0 is about twice as strong as the NL interaction, but only about 10% stronger than FL. Again, the q dependence of PH is much stronger and at 3 frn - 1 PH is now a bout 65 % stronger than NL and about twi ce as strong as FL . At q = 0 the PH matter interaction is about 70% (25%) stronger than NL (FL) , at 3 fm - 1 about 65% (50%) stronger than NL (FL) . For the spin-orbit components the situation is very similar to 200 MeV, albeit amplified. The main difference is that all the analyzing powers converge again at 3 fm - 1 . In the Figures 2.4- 2.11 we show NRIA calculations at 100 , 200, and 318 Me V for elastic and inelastic scattering data from 16 0 and 4?Ca. Elastic cross sections are presented as ratios to the point-charge Ru th er ford cross section '-- ~ ~ 0 0 0 0 0 0 0- 0- 0 0 0 0- 0 0 0 0 0 0 0 0 "' 0 "' "' 0 I "- N ----c,' ~ .., 0 lO 0 lO 0 o 0- i "I' I ~ 0 0- 0.. .. 0 6 0 6 ...; I I C'? .. ,_ C') N ,......_ 0.. I c.. ..s... --a-- ____, j c..> c,' 0.. . - 0 o 0 i "I' 0 lO 0 lO 0 N- 0 0 0 0 .... 6 6 6 I -I (.1s / qw) UP/ DP l.v +- N ,......_ ,0.... .._ c.. I __c_._., _..s_._._. , aj c..> c,' 0.. . 0 lO 0 lO 0 o 0 i 0 0 0 .... 6 0 .... 0 I I '/j.D / .D l.v 4 Figure 2.5: NRIA calculations of a-(q) and Ay for selected states of ?Ca at 100 M e V; the elastic cross section is presented as ratio to the point-charge Rutherford cross section ( a-R) to enhance detail. The bands represent the range of variation of the calculation due to the different free interactions . The data are from this work . 41 ? -- ? I a .._.._.., , 0 N 0 I I lO 0 lO .0. .. 0 0 .0.. . ~ 0 0 0 I ('l ? N ,-.... I ..a... 0- 0 N 0 0 I I ~ lO 0 lO 0 0 0 0- 0 0 0 I (.1s/ qw) UP/ np 'v +- N ,-.... .0... .._ I Q. Q. ? .. a... .__,, 0 0- ~ 0 "' 0 i 0 lO 0 lO 0 0 0 .0. .. 0 0 0 0 I 'llIJ / D 'v Figure 2.6: NRIA calculations of ~ CT' N .., 0 0 i I I C? ll) 0 ll) 0- 0 0- 0 0- 0 0 -C? 0 I I M 1' I ,, I N ,,.-... ? ... 'I I ..8 : I .... - CT' 0 N N 0 i I 0 ll) 0 ll) 0 0 0- 0 0 0 0 0 0 I -I (.1s/ qur) UP/ DP ?v I ..8.... 0 i N I 0 ll) 0 0 ll) 0 0 0 0 0 0 0 0 ..; I I HD / D ?v Figure 2.10: NRIA calculations of a-(q) and Ay for selected states of 4?Ca. at 318 Me V; the elastic cross section is presented as ratio to the point-charge Rutherford cross section ( a-n) to enhan ce detail. The bands represent the range of variation of the calculation due to the different free interactions. The data are from [Fel 90] . 46 > Q) ..... C\1 ~ ~ * ....... I co s ~ ? ~ CV) --..__ ., II ? ?? ..---i 0.. ~ w I I 0 i , I 0 I.{) 0 . I.{) 0 ..---i 0 0 0 ~ , I I ; I I Figure 2.11: NRIA calculations of Q fo r elas tic scattering of 4?Ca at 318 MeV. The bands represent the range of variation of the calcul ation due to the different free interactions . The data are from [Ble 88]) . 47 2.4 Nuclear Matter Approach 2.4.1 Introduction At low and intermediate energies the nuclear matter approach [Hiif 72] has proven to be an alternative and very fruitful approach to nucleon- nucleus scattering. The optical model in infinite nuclear matter is identified with t he lowest order term in the hole-line expansion of the self-energy or mass operator of the projectile nucleon propagating through the target medium . I I , I Density dependence enters into the model through the effective interaction , 'I I I 'I the so-called reaction or g-matrix . This interaction satisfies the analog of the Lippmann-Schwinger equation, the Bethe-Goldstone equation , and in - cludes medium effects via Pauli blocking and energy shifts in the intermedi- ate projectile- target-nucleon scattering states . Further density dependence enters through the the various averaging procedures which are used to reduce the energy and momentum dependent interactions to simple local forms . For a nucleon with energy E and momentum k moving in infinite nu- clear matter of density13 (i.e. Fermi momentum) kF one can write down , following Hiifner and Mahaux, the average complex potential felt by the incident projectile as the diagonal , plane wave, antisymmetrized two- body Brueckner reaction matrix element U(k,E;kF) = L (pklg(w)lpk )A, ( 2 .48) IPl(p)(k)) - l(k)(p) ) is the antisymmetrized two- body plane wave function, and pis again the momentum of the bound nucleon14 . To account for off-shell effects ( e. g. the effects of short-range correlations) , the starting energy w = E + 1:(p) is defined self-consistently for all particles above and below the Fermi level. This is done by chasing the single-pa rticle energy 1:(p) as 1:(p) ~ p 2 / 2m + Re[U(p, 1:(p) ; kF )], (2.49) I I Ii,;, with the nucleon mass m and the (self-consistent) optical potential U; in , I I 1:11 ! lj li I ;11: I I 1:, this equation we have also approximated the full potential1 6 by its real part I '. I !1 1: [Bri77 / 8] . 11 1,1 l'I The reaction matrix satisfies the Bethe-Goldstone equation I 1, g(w) = v + vQpG+(w)g(w) (2 .50) 14 It is a fundamental result of many-body theory tha t in the cluster expansion of th e total energy all self-energy terms to all orders cancel against the terms involving the single- particle potential U, provided the above form for U, also known as Brueckner-Hartree- Fock condition , is satisfied (for finite nuclei additional conditions for the off-diagona l matrix elements between hole states exist). Also, it is easy to see that U indeed represents the average effect of all particles in the medium on the particle in a state k . With g being the effective interaction between particles in the medium, the potential energy for a pa rticl e in state k is just the interaction energy of a pa ir of particles in states k and p , summed over all occupied states p [Pre 75] . 15 Nakayama and Love [Nak 88] discuss to some extent the sensitivity of their g-matrix to the choice of the single-particle energy. Specifically, they set the potentia l at la rge momenta, where the real part of the full y self-consistent potenti a l becomes repulsive , to zero . They find, however , only sma ll sensiti vity even fo r the s trong spin-ind epend ent isoscalar central component which should be pa rti cularl y sensitive to the effe cts of short- range correlations . 49 where v 1s the internucleon potential , and the Green fun ction (2.51 ) includes outgoing boundary conditions and medium effects through the influ- ence of the average potential on the single-particle states 16 . In this equ ation , q1 and q2 are the m omenta of nucleons in intermediate sta tes. The projection operator Q from Section 2.3.1 becomes for nuclear matter the Pauli operator I I Q p with the properties I I (2.52 ) otherwise. This ope ra tor , therefore, restricts intermediate scattering states to outside the Fermi sphere. To calculate the reaction matrix g, one can define the correla ted two- nucleon wave function 7./; by g

is the sam e as v a ppl ied to t he actua l (co rrela ted) wave functi on. This supposition , the independent pair m odel, is j ust ified if t he healing dis tance fo r t he co rrelated wave function is small , which is to a good approximation t he case for low density [Pre 75] . 50 equation for the correlated wave function (2 .54) These developments are very similar to those in Section 2.1 for the free NN scattering case and the t-matrix . 2.4.2 Density Dependent Interactions Starting from realistic NN potentials, several complex , energy and den- sity dependent interactions have been constructed for nuclear matter for me- , I : ) dium energies below about 400 MeV . Brieva, Rook and von Geramb [Ger 79] constructed an interaction (BRG) based on the Hamada-Johnston potential [Ham 62], the Hamburg group under von Geramb [Ger 83, Rik 84] an inter- action (PH) based on the Paris potential [Lac 80], and another interaction (NL) based on the Bonn potential [Mac 87] was constructed by Nakayama and Love [Nak 88]. More recently, Ray [Ray 90] evaluated medium modifi- cations to the Watson optical model for energies above the pion threshold . The resulting interaction is based on a nucleon-isobar coupled channels po- tential model [Ray 87] which explicitly includes NN inelasticities in the form of NN, N ~(1232) and NN*(1440) channels . In the following we want to outline briefly, how the PH [Ger 83 , Rik 84] NL [Nak 88] and LR [Ray 90] interactions were generated and then discuss some of their important prop- erties. * * * 51 The Bethe-Goldstone equations, Eqs . (2 .50) or (2.51), are the starting points from which all of the abovementioned effective interactions are com- puted . The first step in these calculations is a partial wave decomposition of the respective integral equation to be solved . For an operator F( k' , k) we can write fo r each isospin channel (S'IF(k', k)IS) = 41r L iL- L'ytJ5 ,J(k')Fff,5 'T(k', k)Yfs~(k) Pr, (2.55) LL'JM 1' where I I I Fft,5 'T(k', k)Pr = 2- j dk' dk Yff; ,i(k')F(k' , k)YfsJ(k)Pr , (2 .56) 41r and the spin-spherical harmonics are defin ed as Yfsi(k) = L (LML;Slvfsl J M)Yt L(k) x'ff5 . (2.57) ML,Ms It will also be convenient to defin e Fff,ST = Ff{T . Solving the full Bethe-Goldstone equation for the scattering problem in nuclear matter is a very complex and numerically difficult problem and one I I : employs, therefore, certain approximations to simplify the propagator. The first approximation, spherical angle averaging of the Pauli blocking operator Qp, is a standard procedure which has been shown to be a reasonable and quite accurate approximation in nuclear matter18 . If we define K = k + p to be the total m om ent um of the interacting nucleon pair , K = ?( k - p) to be 18 Nakayama a nd Love discuss in their paper [Nak 88] the uncertainty in t he in ternct io11 due to the use of an angle averaged Pauli operator Q p and fi nd for the largest interact ion com ponent , the isoscalar, spin-independent central com ponent, tha t a 20% cha nge in Qr corresponds roughly to a 10% change in the m odulus of the interaction . 52 th eir relative momentum, and q = Hq 1 - q2) to be the relative momentum of the intermediate states (momentum conservation also yields Q = q + _ l q2 - K for the intermediate scattering states), Eq. (2.52) a11d ang1 e averaging combined give tl1e nonrelativistic Pauli function [Bri77 / 8) 0, a < 0 a, 0 :::; a :::; 1 (2 .58) 0, a > 1, where a = (? 1 { 2 + q2 - k} )/ J{ q. Here, and in all the following integrations over tl1e angle between two vectors, we always choose one of the vectors to be oriented along the z-axis . Ray evaluates for his interaction an angle averaged Pauli blocking operator for each of tl1e three clrnnnels NN, Nb. and NN? using relativistic kinematics to relate two-body c.m. and laboratory frames [Ray 90) . The energy denominator in the propagator can be averaged in several Ways. First we observe that tl1e single-particle energies t:( q) in Eq . (2 .51) contain implicitly tlie angle between the total momentum Kand tl1e relative momenta ,,._ and q. The NL [Nak 88) interaction is constructed using tli e method proposed by Brueckiier and Gammel [Bru 58} w11ich treats the angle averaging procedure in an approximate way. The metl10d consists of writing a polynomial expansion of t:( qi) + t:( q2) and expressing q 1 and q 2 as ?K ? q ' respectively. Then, in tl1e quartic term , ( K. q )2 is replaced by its spheri cal average _!:_JdiJ (K ? q) 2Qp(K, q; kF)- (2 .59) 41r 53 To fourth order in the energy expansion, this is equivalent to replacing in the single-particle energies q1,2 ---t q? = ?K 2 + q2 ? [f ?Q p(K,q;kF)Kq . The same procedure is applied to the starting energy w, when expressed as e:(k) + e:(p); one only has to replace q by"' [Bri77/ 8] . The PH [Rik 84] interaction uses a slightly different approximation scheme. First, the kinetic energy terms are collected in terms of the relative momenta"' and q, then angle averaging is performed on the individual poten- tials, which bear the full angular dependence, without any approximations. Thus , for instance, for the projectile with momentum k we have J dK U(l?K + Kl)Qp(K , K; kF) (2 .60) JdKQp(K,K ;kF) and similar t erms for the nucleons with momenta p , q 1 and q 2 . The LR interaction which is based on Watson multiple scattering ig- nores the self-energy of the incoming projectile and applies binding energy corrections to the target nucleons only. Here , a quadratic expression of the form U( 2 2 1t ) = A+ B 1t is being used . For the NN channel, with exception of the A parameter of the initial state, the parameters are chosen to reproduce the well depths of fitted Schrodinger equivalent real, central opti cal poten- tials from Dirac phenomenology. The binding potentials for Nb,,. and NN " were assumed to be 60% that of the NN channel. Instead of the above aver- aging schemes Ray makes an effective mass approximation in combining th e kinetic energy terms with the velocity dependent B terms. He thus arrives at a simple form for the energy denominator which includes the reduced effec- tive mass of the target nucleon and its effective momentum in the entran ce 54 channel. For the calculation of this momentum , the correct c.m. relativis- tic value was used and finally, for nucleon-isobar channels, also the energy dependent isobar widths f were included [Ray 90] . In the following , we want to briefly discuss the gen eralized ref erence spectrum method [Bri77 / 8] as one representative example of how the Bethe- Goldstone of the scattering problem in nuclear matter can be solved . This t echnique transforms the integral equation for the correlated wave functi on ,/; into a system of two coupled differential equations, which are then read- ily solved by numerical quadrature and partial wave decomposition . Let us adopt a simplified notation and write QpG+ in Eq. (2 .54) as Gt. The gener- alized reference spectrum method is effectively an interpolation between the two limiting cases of ? free NN scattering : here Gt becomes the free propagator Gt and Eq. (2.54) reduces to the Lippmann-Schwinger equation. The pole in the Green function introduces a phase shift in the asymptotic wave function. ? the bound state problem: w < 2E( kF) and the kernel of Ct is always non-singular and positive due t o the Pauli principle . Asymptotically, no phase shifts occur and the correlated wave function ,/; (which is purely real) heals towards the uncorrelated plane wave cp. To achieve this interpolation Brieva and Rook separated the Green functi on ct into two parts (2 .61) 55 where the two components have t he fo rm (2.62) G+ - Cp F - m Q2 + 2+ ? ? 0 q ?~ Here q is agam the relative momentum in the intermediate stat es , Q0 is the pole position in Gt, and the other parameters are optimized to sati sfy Eq . (2 .61) as closely as possible . T hat this is indeed a good approximation has been shown in the paper by Brieva and Rook [Bri77 / 8] . ,, I I Now the_i ntegral equation for 'I/;, Eq . (2 .54) , can be written as a sys tem of two coupled differential equations A = q; - GRv 1./; (2.63) 'lj; = A - Gt v'f/; where 'I/; should be a good approximation to the true wave fun ction . The quantity A is an auxiliary wave functi on . This system of differential equations can be also written as (\72 - -y2)[A - ?] = mcRv'lj; (2.64) (\7 2 + Q~)['lj; - A] = mcFv'f/; , which can be solved numerically by means of partial wave expansions . How- ever , one can easily recognize the following limiting cases ? for free NN scattering with th e free propagator Gt one has CR = 0, cF = 1 and A = q; . One is left with th e Schrodinger equ a tion fo r free N N scattering (\72 + QG )'I/; = mv'I/;, (2.65 ) where Q 0 is the asymptoti c relative momentum . 56 ? for the bound state problem one has CF = 0 because of the non-singular kernel. Hence, one is left with the traditional reference spectrum me- thod equation where A = 'lj; , i. e. (2 .66) * * * Although the generalized reference spectrum method was used by von Geramb, Brieva and Rook for the BRG interaction [Ger 79]) , another pro- cedure was chosen for the PH interaction. With the above approximations for the numerator and the denominator of the propagator, Eqs . (2.58) and (2 .60), the integral equation for the correlated wave function in coordinate- space, ui,ff (r, a), was solved i~ each partial wave J :S: 10 with standard matrix techniques for Fredholm integral equations of the second kind ( a represents the dependence of the wave function on E, k, p and kF ). The self-consistency process was initiated with the choice U = 0 and was iterated once [Ger 83, Rik 84]. The prescription of Siemens [Sie 70] was then used to construct a local energy and density dependent effective interaction in coordinate-space. The method simulates, in an average way, all the properties of the correlated wave functions, including the behaviour at small r . In this way, im portant off-shell amplitudes which arise from short-range, repulsive anti correlation effects which tend to keep identical nucleons apart are retained at least on the average [Kel 89a] . The basic idea is that with the correlated wave functi on 'lj; the plane wave matrix element of g can be deduced from (cplg lcp) = (f~,~~). 57 Explicitly, one has (2. 67) where the vf,f!: (r ) are the two-body NN potential radial form fact ors of the Paris potential in the channel ( J ST; LL") [Rik 84] . The angular momentum indices are such that the unprimed L refers to the entrance channel, while the primed ones refer to subsidiary channels . An interaction in the form of a local pseudopotential, Eq. (2 .32) , can be obtained if one expresses g( r) as a scalar product of the rank k tensor opera.tors Rk(r), acting only in coordinate-space, and Sk , acting only in spin and isospin space 2 g(r) = I: Rk(r) ? Sk- (2 .68) k=O Using partial wave analysis and Racah algebra, one can isolate the t ensor amplitudes which are related to the g-matrix elements of Eq . (2 .67) . On e finds for instance for the central component (k = 0) that S0 = PsPr and (2.69) In the here adopted notation we have :i; = 2x + 1. The remaining L depen- dence in the Rk can be eliminated by performing a weighted average over the Fermi sphere. The appropriate weighting fact or for the central interac- tion is the sta.tistical fact or L times the probability that the relativ angul ar momentum of projectile and target nucleon is L [Ke! 81], i.e. WL = r dp lh(~r)l2 . (2. 70) l1p1 -s_ kp 58 With this result we get for the cent ral interaction "' L' R(oL L ,ST) C L, ? C:W? 9sr = (2 .71) where the fact ors c: restrict the sum to allowed antisymmetrized states . Anal- ogous expressions for the spin-orbit (k = 1) and tensor (k = 2) components a re given in [Ger 79 , Ger 83 , Rik 84]. Finally, following the procedure in Section 2.3.4, a parametrization in I I t erms of Yukawas is done. The fin al interaction is available for densities between 0.5 and 1.4 fm - 1. However , for kF - 0, the PH interac tion is only required to reduce to the free NN t matrix for the two momentum transfers q = 0 and q = k , which might explain the large differences th at have been found , particularly at intermediate momentum transfers , fo r the low-density PH tensor interaction and the tensor components of the FL t- matrix [Kel 89a] . * * * The NL interaction is calculated in momentum-space on th e energy shell by solving the operator equation , Eq . (2 .50) , directly for the gf{T (K , "- ,"- )in each Pauli allowed partial wave channel (J ::; 10 , 15 , 18 for TL(MeV) ::; 100, 100 < TL(MeV) ::; 270 and 270 < TL(MeV) ::; 425 , res pectively ) vi a matrix- inversion19 [Nak 88]. The calculation is fully self-consistent . Apart from the approximations for the propagator described above , a simple Fe rmi average l !J The method which is generall y used , is the one described by Hafte l and Taba kin [Haf 70] . 59 for the m agnitude of the initial mom entum of the struck nucleon was chosen, namely (IPI ) = ?kp . Subsequently, fo r simplicity, the magnitudes of t he total m om entum K and the initial rela tive momentum K- were determined from k and p by an unweighted average over the direction of p with respect to the local m om entum k of the incident projectile (K) (2. 72) where k> (k<) is the larger (si:naller) of k and ?kp . The advantage of thi s sim- ple averaging procedure is that nonrelativistically one recovers the free NN t m atrix in the limit kp --> 0, independent of momentum transfer [N ak 88] . Simply substituting the gfJ!'(K, K , K) back into the partial wave expansion for the g-matrix, gives a local and angular momentum independent interac- tion for a particular projectile energy, without further averaging. F in ally, the interaction is cast in the operator form , Eq. (2 .40) , using cert ain rela- tionships between the g-matrix and the coeffi cients fif r , g~5 and gj, [Nak 88, Nak 84] . Subsequently, the interaction components are fitt ed for several en- ergies and densities to sums of antisymmetrized momentum-space Yukawa forms, similar to Section 2.3.4, using only on-shell momenta q < 2k . Nakayama and Love have studied , to a certain extent , the off-shell and nonlocal behaviour of the gf0 component of their interaction . The auth ors justify the on-shell prescription which was used to constrn ct their local inter- action by observing that at moderate excita ti on energies the on-shell or near on-shell matrix elements will be the dominant ones due to th e limited spread in relative collisi on m oment a allowed by the momentum di stributions of the 60 initial and final target state wave functions . To show the off-shell effect ' Nakayama and Love compare at kp = 0 tl1e parametrized (i .e. local) form of the g-matrix with the exact g-matrix, evaluated under special kinematic conditions: while t11ey vary the magnitude of the final relative momentum K', both K and ,,.,, are taken to be parallel (i.e. the on-shell point is at K' = K ' where qQ = 0) . They observe that large differences between the exact and local interactions only exist for such significantly different relative momenta which are unphysical and not allowed by the nuclear wave functions . To study nonlocality, they make use of tl1e fact that in momentum- space a purely local interaction depends solely on the momentum transfer q but not on the exchange momentum transfer Q. Thus, examining the Q dependence at a fixed value of q samples the overall non1oca1ity of an interaction . Considering Eq. (2 .50) , they observe that for a purely real NN input potential v the nonlocality of the imaginary part of the interaction will be entirely due to the correlation term G"f,g . A comparison with the Q dependence of the bare NN potential, in this case the Bonn potential [Mac 87) which itself is strongly nonlocal due to the exchange of er and w mesons , seems to indicate that the nonlocality contributions from the potential greatly outweigh those due to correlations . * * * For the LR interaction, the evaluation of the Watson t-matrix wu.s ? ?JST ( ) ? achieved by introducing a correlated wave funct10n , u/3LL' r, a ' rn coordi - 1l a t e-space and solvm. g equa.t1?0 n E q. ('2 ? 54) in each partial wave and for eacli 1 . b l I a with matrix techniques . The treatment of nuc eon-1so ar c ianne I-' 61 the propagator has been discussed earlier. With the correlated wave func- tions, medium modified NN amplitudes f are generated on the energy shell with f = (lvl'l/i ) for specific initial and final two-nucleon spin projections [Ray 90]. Following the notation of [Ray 85], these amplitudes are then transformed into Wolfenstein amplitudes for (pp) and (pn) channels (2. 73) where l.5fm. For 318 Me V even the NL and LR interactions produce potentials with significant radial structure. 21 The "wiggles" in the small ImULS poten t ia ls are due to the fact that for these LDA ca lculations , we evaluate the density dependence of the in teraction using q-folding a t each projectile position and by interpolating expansion coefficients of a given Yukawa tabl e. The density dependence of the interaction which is represented by such a table is not entirely smooth . Evalua ting the interaction in coordina te-space instead , compri ses effect ively a sm oothing process because the potentials a re first ca.lculated on a radi a l mes h and then interpo lated by a sm ooth polynomia l. On th e other ha nd , reparamet ri zed t heo ret ica l interac tions, as well as the empirica l interact ions in Chap te r 7, do have smooth density dependence and, hence, produce smooth poten t ia ls. In either case, the wigg les a re too small t o affect the observables . 67 The very characteristic radial shape of the LDA potenti als, commonly called "wine- bottle" shape, is due to the delicate competition between short- range repulsion and attraction in the interaction. The details of the balance depend upon the difference between the gradient of the density and the gradient of the repulsive component [Kel 89a]. The energy dependence of the shape is du e to the different energy dependencies of the direct and exchange parts of the folding potential , the exchange part having a slightly sharper energy dep enden ce than the direct part . As we will see later the wine-bottl e shape also arises from our empirical interaction , the IA2 [Ott 88], and Dirac phe- nomenology [Ham 90]. Finally, the equivalent local potentials which will be dis cussed in Section 2.7.2 also show this shape. 68 V -;:::::s ' I[) ,/ "/ (, ' --8-- (") ..... fl W.J Figure 2.17: Optical potenti als for elast ic scattering of 318 MeV protons by 4?Ca for the PH (solid line ), NL (short dashes), LR (dashes) , and FL (long dashes ) interactions . 74 In F igures 2.18- 2.25 we show LDA calculations fo r the same data and m the same format as in Section 2. 3.6. The line code is the same as in the previous figures for the optical potenti als: PH (solid) , NL (short dashes) , and LR (dashes) . All of the calculations employ self-consistent distorted waves and transition densities from electron scattering ( see Appendix A) . While the cross section calculations based on the PH interaction look reasonable for elastic scattering and the 31 states at 100 MeV, neither the 11 state of 16 0 , nor the 32 state of 4?Ca are particularly well described . The NL forward cross sections are generally too high , a consequence of the weak absorption of the NL potenti al. The PH interaction provides an overall better description of the analyzing powers than the NL interaction which gives much too positive analyzing powers at large momentum transfers, and which for 4?Ca produces rapid oscillations in the analyzing power which are not present in the data. Nevertheless , neither interaction describes the data particularly well . At 200 MeV, although both the NL and the LR interaction describe the elastic cross sections slightly better than the PH interaction , their predi ctions for the forward angle elastic analyzing powers and spin rotation functi ons fall well below the data . The PH interaction, on the other hand , describes these data quite well. Inclusion of Pauli blocking and short-range anti correlations lower the inelastic forward cross sections and fill iu strength at large momen- tum transfers . The analyzing powers become more negative and are closer to the data. On the other hand , if we compare the LDA calculations for the 32 state of 4?Ca with the corresponding NRIA calculations in Figure 2. 7 we 75 do not see much improvement : on the contrary, t he second maximum in the cross section appears to be slightly to high . The reason for this behaviour might be the special shape of the transition density which has a st rong lobe both in the high-density interior and the low-density surface region . It is also striking that all the LDA models overestimate the forward cross sections of the surface-peaked 31 peaks . This sugges ts that the effec tive interact ion is m odified even for low densities. The spin rotation functions are clearly improved over the NRIA in Figure 2.8, especially at forward angles . Finally, the LOA calculation follows more closely the large amplitude of the oscilla- tory pattern which is described by the analyzing power data. While the PH interaction is clearly superior at small momentum transfers , it appears that the NL and LR interactions become slightly superior at larger momentum transfers . Overall , the PH interaction provides the best description of all the data. While the cross section predictions for the LR interaction are very similar to those for the NL interaction , the LR analyzing powers are clearly superior to those of the NL interaction. Analyzing powers for energies at or below 135 Me V are especially poor with the NL interaction . At 318 Me V the PH interaction provides a clearly superior description of the 160 cross section data, while the NL and LR predictions fall well below the data. The PH analyzing powers , on the other hand , appear to be shifted a little bit too much towards lower momentum transfers while th e two other interactions follow the data more closely. For 4?Ca the NL aud LR interactions perform better on the cross sections and approach the P H predictions . Their predictions of the analyzing powers and the spin ro tation 76 fun ction at larger m omentum t ransfers are st ill slightly superior to the PH predictions . It is significant , however , that even the LDA is not able to suppress enough the forward angle analyzing powers at this energy. Kelly et al. attribute the superior performance of the PH interaction over the NL interaction for isoscalar natural-parity transitions to the special procedures used in reducing the g-matrices to a local form . As discussed above , the PH interaction is believed to reproduce more realisti cally the short-range correla tions of the interaction , thus giving rise to off-shell be- haviour that may be m ore realistic . Since the on-shell behaviour of the two interactions , as judged from the the Pauli suppression of the forward scat - t ering cross section , appears to be comparable, the off-shell performance of an interaction seems to be indeed important . In spite of the careful justifi- cations for their on-shell and momentum averaging prescriptions leading to a local pseudopotential form , the off-shell behaviour of the NL interac tion by Nakayama and Love might be inadequate . On the other hand , it has also b een observed that the NL interaction , in some respects is more sound than the PH interaction , especially with regard to self-consistency and the low density limit . And indeed , the NL tensor interaction, being in better agreem ent with the FL t-matrix , gives a better description of the excitation of stretched states than does the PH interac tion [Kel 89a.]. A comparison of the PH and NL interactions to the LR interact ion is less st raight fo rw ard aud we defer it to a la ter section . 77 ? ?. .. ? . .. -? 1 N ....-. I ,,??? .. s~--??' ..... - ??? ---- :_-_. ., 0 i N 0 \() 0 \() 0 I I ~ 0.. .. 0.. .. 0.. .. 0 _; 0 0 0 I ("l . ?-? ,_ ? N .. . - (") I __ ----- ---? ..s... ---- r::1' 0 N 0 \() 0 \() 0 0 0 i I 0- 0 0 - 0 0 0 I -I (.1s / qw) UP/ DP l.v _,? . N +- ? 0 j -'-- -- --~--- ..s... 0.. ? --- - -?- ----0 - ~ ? r::1' : 0 i 0 \() 0 \() 0 N 0 0- 0 0 0- 0 0 0 I Hn / n Av 16 Figure 2.18: LDA calculations of and x (for simplicity, we consider here only the scalar and vector potential fields) (E - m - S - V) - u ? p x = 0 (2.87) u ? p - (E + m + S - V)x = 0. The second equation yields for the lower component U?p X = ----- . (2.88 ) E+m+S - V Substituting back into the equation for th e upper component , one gets 1 (E - m - S - V - u ? p-----u ? p) = 0. (2 .89) E+ m +S - V 23 The amplitudes for these negative-energy states vanish when the scattering nu cleon is far away from the nucleus ; they are virtuall y present, however , in t he in teraction reg ion where the optical potenti a l is strong, i.e . in the immediate vicinity of the nucleus. 91 -+-- z Figure 2.26: Z-graph for a Dirac particle scattering from an external potential at times t 1 and t2, where t i < t2. 92 Assuming the potentials S and V are almost constant with respect tor, allows us to neglect the spin-orbit and Darwin terms. Rescaling the wavefunction by the substitution 1/; = E+m~S - V leads with k2 = E 2 m 2 - to an equation in the form of a Schrodinger equation for the central potential with relativistic kinematics: (2 .90) where the equivalent Schrodinger potential is (2.91) If one assumes a local tp model for the optical potential, one can set S = sp and V = vp and write Eq. (2 .91) as m 1 2 2 2 UNR = tNRP = ( Es+ v)p + E(s - v )p . (2 .92) 2 Since only the first term of tNR remains in the limit p ---, 0 limit , the first term of the potential U NR comprises the nonrelativistic impulse approximation . The second term represents the relativistic, density dependent correction due to virtual nucleon-antinucleon pairs . Since in actual nuclei the absolute value of s is larger than that of v, the relativistic correction manifes ts itself as a short-range repulsion which becomes stronger in the nuclear high-densi ty interior region . Other form s for the two terms in Eq . (2 .92) can be fo un d by expanding the Dirac wave fun ction in terms of positive and negative-energy states 1/; 1 = A ?1/; of the potential-free Dirac equation24 . Elimination of negative-energy 24 The projection operators are defined as A? = ?{~,"', where jJ = -y"Er - 1 ? p . 93 components from the Dirac equation then yields an equation for the positive- energy component. At the level of approximations that has been used before, one gets (2.93) where (;?? = A ?(JA ? and where the pair potential is {;pair = {J+ - [E + Jp 2 + m 2- {J--J-l {J - + . (2.94) The potentials(;+ - and(; - + are responsible for the scattering into and out of the negative energy states. In Figure 2.26 these potentials are represented by the little bubbles at end of the wavy lines. Thus, the equivalent Schrodinger central optical potential is essentially the combination of a part (;++, which is the sum of strong scalar ( ~ - 400 Me V) and vector ( ~ +300 Me V) potentials , and a pair term which includes coupling to the other energy sectors of the Dirac space. N onrelativistivcally, the 2 22~ ( S - V ) term is linked to the spin- orbit force . If one includes additionally medium effects like Pauli blocking etc., a density and energy dependent interaction for elastic scattering at intermedi - ate energies is well described by [Che 86] (2 .95 ) or , with the Brueckner g-matrix by t(p) ~ g(p) + 5tnc(P), (2 .96) where 5tnc(P) = -1 (s 2 - v 2) p. (2.97) 2E 94 The 1/ 2E factor in the relativistic correction term suggests that in the high energy region the Dirac and Schrodinger approaches might converge. 2.5.4 IA2 Calculation Results In Figures 2.27-2.30 we compare the full IA2 op tical potential (solid) for elastic scattering of 200, and 318 MeV protons from 160 and 4?Ca with a nonrelativistic LDA potential based on the PH interaction (long dashes). In the "no-pair" analysis of the IA2, all couplings to negative-energy states are eliminated and all the relativistic nuclear densities are taken to be equal to the measured nonrelativistic matter density. The Schrodinger potenti al equivalent to the Dirac potential from the "no-pair" analysis is called the NP potential (dashes) . Finally, for comparison we also display an NRIA potenti al based on the PH t-matrix. Comparisons of the IA2 with our empirical model and a recent , very successful Dirac phenomenology by Rama et al. [Ham 90] will be made in Chapter 7. At 200 MeV the real central IA2 potential is , although on the whole still attractive, much more repulsive in the nuclear center than any of the other potentials , including the LDA potential which is about intermedia te between the IA2 and the NP and NRIA potentials. Like the LDA potential , the IA2 potential has a "wine- bottl e" shape. The NP potenti al is slightl y more repulsive in the center than th e NRIA potenti al but , like th e NIUA potc11ti al, does not have the surface depression of the .LDA or IA 2 pote11ti a.l. Fn r I.h e imaginary central component , the IA 2 potenti al is virtually identi cal to th e NP and NRIA potentials , being only sli ghtly less absorptive for 4?Ca. This 95 ... fact is due to the absence of Pauli blocking . T he real spin-orbit potentials are essentially all the same for 160; for 4?Ca the IA2 potential resembles somewhat the LDA potential. The imaginary spin-orbit potentials differ significantly, but are again too small to affect calculations significantly. At 318 Me V both the IA2 and the LDA potentials become repulsive in the nuclear interior , while the NP and NRIA potentials stay attractive. The IA2 potential stays repulsive even at the center where the LDA potenti al is again attractive . The strong repulsion in the real part is due to the virt ual N N pairs . In the imaginary central part of the optical potential for 16 0 we see an interesting effect whose discussion we will pick up again in Chapter 7 in context with our empirical effective interaction: the IA2 imaginary central potential at this energy becomes more absorptive relative to the NRIA po- tential. This effect, which becomes very pronounced for 500 Me V, is in thi s work often called "anti-Pauli" blocking. 96 N '---~--'-- ~....L.:..l-_:_.____---'---~~- 0 0- I() 0 I() 0 IO ' l{) {). ll) o::::V; __0__: c..o... "" 0 C") ~- -s ~ II ~ - (") ..... a. '-' t.J )'\ 1-.. N 1/ _-pJ--~ -- V 0 0.. . ll) 0 IO 0 I.O.. (") C\I 0 0 0 0 0 0 0- 0 0- C\I 0 I I I I I (Aaw) s,O ocf (Aaw) s,O 'Ulf (l ocJ (/\aw) :)fl W./ Figure 2.29: Comparison of t he full IA2 (solid) , LDA (long dash es) , NP (dashes), and NRIA (short dashes) optical potentials for 318 MeV elasti c scat t ering by 160 . Both LDA and NRIA are based on the PH interaction . 99 ID N 0 0 C\I o"' 6 0 2cF0 to be damped by a fact or (1 - dK-} ), where d decreases with energy as E 10 . T he dam ping fact or is shown as a functi on of the (dimensionless) energy E and Fermi m omentum "-F in Figure 2.33 . The density dependence of the real part of the central interaction , Retf0 , 1s best described by the addition of a short-ranged repulsive core whose am- plitude is p rop ortional to density, i.e. K-} . The repulsive core is due to the anticorrelation between identical nucleons and its effect is to enhance the differential cross section for large m omentum transfer . As can be seen for example in Figure 2. 34 where the different symbols and curves represent dif- ferent densities , with increasing density the curves are displaced upwards by an am ount p roporti onal to density and almost independent of mome11t11m transfer . The cur ves are not quit e parallel because the finit e range of t he repulsive core redu ces its effectiveness and thereby causes the cur ves to draw t oge ther fo r large m omentum transfers [Kel 89a]. With these results , a param etrized form for the vanous component s 115 I.() N ..' ' ' ' 1 ' CJ t,.. ' .' le! ? C\1 . :' I II \J,) I N \J) '', I ? I I I : I I I I ; I I I ? I I 0 co I 0) r- .... f I I 0 I 0 0 II i I II II I II I.() I ,:.. le"!" ,:.. "" I le! ~ .'I .I le! le! I , . I I 'I I f, .I I , I 0 C\1 c.o 0 cD 0 0 0 Figure 2.33, Clemente! and Vilh estimate of the Pauli blocking facloc 116 of the isoscalar effective interact ion can be developed. Following the (new) n otation of Kelly et al. [Kel 90b], all the central and spin-orbit components of the interaction can be parametrized by separate fun ctions of the generic form N t i ( q , "'F ) -- (Si - di KFo:? )t(i J)( q ) + "'-FYi q 6, '"' 0 a ;nY /3 ,( q I ?;n )? (2.112) n = l H ere, tUl(q) is a free interaction , y( x) = (l + x 2t 1 is a Yukawafunction , and the ?n are various mass p arameters whi ch were chosen to optimize the fit . . ' , ..' If the individual components of the interaction are considered to be appro- '' . pri a te Fourier transforms of Yukawa expansions , one finds th at the natural I' '? exponents /3 are 1 for central , 2 for spin-orbit, and 3 for tensor interactions . .., Similarly, for the tensor interaction 5 = 2 is used and 5 = 0 otherwise . As . .; we have already discussed , the Clemente! and Villi model predicts for the imaginary part of the central interaction a = 2 and d ex E 10 . In order to recover the free interaction at zero density, the scale factors S are required t o be unity for theoretical effective interactions . This restriction can and , as ?' : I we will see, must be relaxed for the phenomenological analysis of data. We performed empirical interaction fit s for the PH, NL and LR effective interactions for energies between 100 MeV and 500 MeV. We used the free PH t -rna.trix for the PH fits and the FL t-matrix for the LR fits ; the NL interaction contains the t -rnatrix as the kF ----> 0 limit. The PH interact ion was fitt ed in the ranges O S q S 3 fm - 1 and 0.6 S kF $ ] .4 fn, - 1 with a step size of 0.1 fm - 1 for the momentum transfer and a. step size of 0. 2 fm - 1 fo r the Fermi m om entum. The NL interaction was fitt ed in the same momentum 117 transfer range, and with the same step size for q, for Fermi momenta in the range 0.6 :S kF :S 1.4 fm - 1 (step size 0.2 fm - 1 ), excep t for 100 MeV where only kF = 0.0 and 1.36 fm - 1 were used because the density dependence is not monotonic at that energy. The LR interaction was fitted for kF = 0.0, 0.7, and 1.4 fm - 1; the momentum transfer ranges were 0 ~ q ~ 2.5 fm - 1 (200 MeV ), and 0 :S q :S 3 fm - 1 (318 MeV and 500 MeV ). The c.m . wave number was evaluated for 160 . The fitt ed parameters are listed in Tables 2.1- 2.3, and both the theo- re ti cal interactions and the empirical fits are shown in Figures 2.34-2.42 (the PH and NL parameters for 135 MeV are from [Kel 89b], the PH parameters for 180 MeV from [Ke! 90a]) . Considering that only two parameters are be- ing used for each component, the fits are remarkable over the whole energy range. Also, apart from 100 MeV and 318 MeV where some modifications t o th e mass parameters and exponents are necessary, it appears that one fun ctional form is able to accommodate all the interactions: PH, NL , and LR. 118 R et~ Imt~ R erLS ImrLS 0 0 0 0 TL p au a12 d2 I a21 a31 I a 3 2 d4 I a4 1 C -123 .67 201.13 0.561 -2.29 -20 .09 15.73 0.603 -4. 61 100 ? 0 3.0 - 0 3.0 6.0 - 3.0 e [3310] [2210] [3320] [3220] C -94. 71 181.29 0.443 -6.36 -13 .80 10.71 0.571 -5.26 135 ? 0 3.0 - 0 3.0 6.0 - 3.0 e [3310] [2210] [3320] [2220] C -74 .33 157.32 0.326 -10.27 - 8. 73 7.21 0.586 -5.64 180 ? 0 3.0 - 0 3.0 6.0 - 3.0 e [3310] [2210] [3320] [2220] C -64.15 141.31 0.287 -10 .49 -7 .39 6.40 0.384 -3.36 200 ? 0 3.0 - 0 3.0 6.0 - 4.0 e [3310] [2210] [3320] [3220] C -45 .90 123 .23 0.173 -24.17 -4.61 3.69 0.324 -2. 78 318 ? 0 3.0 - 0 3.0 6.0 - 7.0 e [2210] [2210] [3320] [1140] Table 2.1: Reparametrization of the PH interact ion. Units: Te, (MeV) , d (1) , a (MeV fm 3 ) for central and (MeV fm 5 ) fo r spin -orbi t components, ? (fm - 1 ) ; an entry of 0 for ? is to be interpreted as a delta fun ct ion with ? - 1 = 0 . The exponents for ea.ch component a.re give n in th e fo rm [a,,85]. 119 Ret~ Imt~ RerLS lmT'.LS 0 0 0 0 TL p au I a12 d2 I a21 a31 I a32 d4 I a41 C -186.80 200 .54 0.700 -4. 06 -24 .56 14.20 0.705 -0.69 100 ? 0 3.0 - 0 3.0 6.0 - 3.0 i e [3310] [2210] [3320] [2220] ' . ? C -62. 78 85.15 0.671 -6.64 -18.89 12 .00 0.728 -1.30 ' .f ' ' ' 135 ? 0 3.0 - 0 3.0 6.0 - 3.0 e [3310] [2210] [3320] [2220] C 0.34 24 .93 0.568 -4 .96 -14.14 9.18 0.663 -1.30 ... 180 ? 0 3.0 - 0 3.0 6.0 - 3.0 I e [3310] [2210] [3320] [2220] C 15.00 9.63 0.458 -5.34 -10. 72 7.13 0.610 -1.61 200 ? 0 3.0 - 0 3.0 6.0 - 3.0 ' ,' e [3310] [2210] [3320] [2220] , ' ( C 9.73 18.53 0.280 -9.46 -5.00 3.45 0.052 1.64 318 ? 0 3.0 - 0 3.0 6.0 - 3.0 e [3310] [2210] [3320] [2240] Table 2 .2: Reparametrization of th e NL interacti on . Un it s: Ti (MeV), d (1) , a (MeV fm 3 ) for central and (MeV fm 5 ) for spin -orbit compo 11 e11ts , ? (fm - 1 ); an entry of 0 for ? is to be interpret ed as a. delta functi on wit h ? - 1 = 0. The exp onents for each component are given in the form [a,,85]. 120 Ret~ Imt~ Re-rLs lm-rLS 0 0 0 0 TL p au I a12 d2 I a21 a31 I a32 d4 I a41 C -67 .84 108.10 0.443 -5.46 -8.93 7.54 -0.027 -1.17 200 ? 0 3.0 - 0 3.0 6.0 - 4.0 e [3310] [2210] [3320] [3220] C -38 .89 100 .03 0.263 0.83 -3.31 3.76 -0 .020 -1.53 318 ? 0 3.0 - 0 3.0 6.0 - 2.0 e [3310] [2210] [3320] [3220] C -35 .08 108 .28 0.174 -4.65 -1.03 1.92 -0.007 -1.44 500 ? 0 3.0 - 0 3.0 6.0 - 2.0 e [3310] [2210] [3320] [3220] Table 2.3: Reparametrization of the LR interaction . Units : TL (MeV) , d (1), a (MeV fm 3 ) for central and (MeV fm 5 ) for spin-orbit components , ? (fm- 1 ); an entry of 0 for ? is to be interpreted as a delta function with ? - 1 = 0. The exponents for each component are given in the form [a1,B5]. 121 g b .... ., '? 0 0 . 0 ci ... I I ("'l + + .? ?+ . ? N I -..8.... 0 0.. . 0 0 0 0 0 00 U"l 0 U"l 0 U"l 0 U0 U"l O ION I ... ..".l '?I _. N N I I r--1?-1r---,----,-----.---,--I- ~~--1_ _1 N I -..s.... ..0 uo, 0 0.. . 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 '? '? 0.. . U..".l 0 U"l 0 l() N ... t.O co 0.. . N... ...... t...O. I N N (") (") I I I I I I I I I I I I (clUJ J\dW) Figure 2.34: Reparametrization of the PH interaction (100 MeV) . The symbols show the original interaction for kF = 0.6 fm - 1 (triangles) , kF = 1.0 fm - 1 (crosses), and kF = 1.4 fm - 1 (diamonds) . The curves show two- parameter fits. 122 N I ..E .._.., , . 0 I[') 0 I[') 0 0 "0' 0 - 0 0 0 I -I C'l ' ? ' ~.. ., .' 1 ' ..~.... . N ,......._ '1 I -E I .._,, ,: ,I - er ; I ?' , ; I ? I 0 I[') I[') 0 I[') 0 0 0 0 0 0 0 0 0 0 I[') I[') 0 I ... .. I-[') 0 I[') C'l C\l C\l C\l C\l - -I I I I C'l .''I, '' I I N ,......._ I I '. I E : l ...._..,. , ..... er 0 0 0 0 0 0 0 0 0 00 0 0.., . 0 0 0 0 00 .., . 0 0 C\I 0 I..[.'.). 0... co - < 0 ., o 0- I() 0 I() 00- 0 0 0 I - I (") ~.. ., ..~.... N ,....__ I --8 - er 0 0 0 0 0 0 00 0 II') 0 I() I() .... .. 0.... .. ".....'. ON I I N - I I I N I ..8.... - er 0 0 0 0 0 0 0 0 00 0., ,. 0 0 0 0 0., ,. 0 ' I() ) must vanish . 3.4.2 The HRS Spectrometer The HRS spectrometer, as the K600 spectrometer, is of the QDD type and utilizes the momentum-loss principle . The mode of operation is VHV (Vertical Dispersion, Horizontal Scattering, Vertical Analysis) , a configu- ration which effectively decouples scattering angle and energy. Table 3.4 compares some of the important design specifications of HRS with those of the K600 (normal dispersion mode) [Zei 71, K600 P , K600 L] . 3.5 Detectors We used two types of detectors in the focal plane: plasti c scintillators and multi-wire vertical drift chambers (VDCs) which served as horizontal ( x, 0) detectors . At the time of our experiment the proposed horizontal drift chambers (HDCs) which would have provided vertical (y , ?) information were 150 not yet available. 3.5.1 Scintillators T wo plastic scintillators paddles with photomultiplier (PM) tubes on ei- ther ends were used in all our run periods ( the two scintilla tion det ectors used in January 1987 were originally designed for pion detection with the QDD M and covered only slightly more than half of the available fo cal plane). Both paddles were m ounted behind the wire chambers . While the front scintill a tor (Sl) ha d a thickness of 1/ 4 in , the rear scintilla tor (S2) had a thickness of 1/ 2 in . During the 100 MeV runs a 1/ 16 inch aluminum absorber sheet was inserted between Sl and S2. For the 200 MeV run periods a combination of two 1/ 16 inch and one 0.09 inch aluminum sheets was used . To find the correct op erating voltages for the photomultipli er tubes the stand ard plateau m ethod was used . This involves measuring the count rate as a fun ction of the applied PM voltage and then fixing the voltage in the middle of the plateau . The scintillator stack has several functions . Sl-S2 coincidence provides an event trigger and also a position-independent start signal for the VD C drift time m easurement . Plotting 6.E1 versus 6.E2 allows particle identification and background rej ection . 3.5.2 Wire Chambers The front VD C plane (X l) is positioned along the focal plane. T he rear plane (X2) is parallel to Xl and is mounted at a di stance of 103 .2 mm from X l. The horizontal offs et between the chambers is 79.2 mm , 1. e. channel 0 151 of Xl coincides with channel 792 of X2 (10 channels = 1 mm) . Each cham- ber consists of 160 gold-plated 20 ?,m tungsten sense wires with a spacing of 6 mm. Located between each pair of sense wires are two 50 ?,m guard wires (Be-Cu) such that the overall wire spacing is 2 mm . All the wires are held at ground potential. The active detector area is approximately 100 cm horizontally and 7 cm vertically. Two stretched 1 mil graphite-coated alu- minum mylars constitute the cathode planes ( cathode-to-cathode spacing: 12 .7 mm, operating voltage :_ :::::: -4.5 kV) and serve at the same time as gas barriers . The filling gas is a mixture of 50% argon gas and 50% isobutan e quencher gas . This gas mixture is bubbled through refrigerated n-propanol, an antipolymerizing agent. During the experiment a steady gas flow was maintained. At the operating voltage the electron drift velocity saturates to 46 .1 mm/ ?,s . As in the case of the scintillators , the correct operating volt- ages were found by a plateau measurement in which for a given threshold the efficiency is plotted as a function of the applied chamber voltage . For this measurement all the wires should be illuminated uniformly by the beam. The definition of the efficiency usually includes the requirement of good hit patterns in the chamber . 3.6 Electronics 3.6.1 Scintillator Electronics Signals from the four scintilla.tor photomultipli er tu bes ( th e high -mo- men tun.1 side tubes are denoted by P , the low-momentum side tubes by N) 152 are divided by linear fans (PS 744) into signals gomg to charge sensitive analog-digital converting units (LRS 2249 QDCs) for pulse-height analysis and into signals going to constant-fraction discriminators (EG&G 934 CFDs) ( c. f. Figure 3.3) . CFD output signals are fed into time-digital converters (LRS 2228A TD Cs) and each pair of P and N signals is also collected in a mean-timer unit (LRS 624) to generate a position-independent timing signal for each of the two scintillators . The rear scintillator timing signal is the signal we want to use to define a START for the wire TDCs . Due to its thickness , the energy loss in S2 is larger than in S1 and, hence, the signals are stronger. Also, the front scinti l- lator and the aluminum plate(s) eliminate most of the noise2 . Therefore, the Sl mean -timer signal should be delayed with respect to the corresponding S2 signal. Pulse shaping and delay of the S 1 signal are done with a computer programmable delay (IUCF) , the S2 mean-timer pulse is shaped in a dis- criminator unit (LRS 821). Figure 3.3 schematically shows the pulse shapes and their relative timing . Finally, the S1 and S2 signals are collected in a PS 755 module with coincidence level two. The coincidence unit is vetoed by the run gate and the CAMAC read from the output register (JORWAY 41) . 3.6.2 VDC Readout Electronics For ea.ch VDC there a.re ten printed boards (LRS 2735B) with four am- plifi er chips per boa.rd . Each board thus amplifies and di scriminates signals 2 The fast circuit in Ma rch 1988 used Sl as a basis for timing. 153 S2N S2P SIN SIP ~.... I! I I! I I! I I! oq .C.,: ('I) ~ ~ 11 11 ~ l~I en .. . . s s~ f I I u t-s s 0. c.....,... .;., = ,,-__?.. .;,i..i. . .0.. t".l -(D () ... ~ ~ 1 " t-s s 0 I i 2. I i () i i i "' I F.'a .rt Gat.e Fas't Start rrr-u Clear Clear S2 ~ If veto (rom SltS2t4NH Output Register of sixteen consecutive wires . This is schematically shown in Figure 3.4. At some stage of the experiment we were concerned about cross talk between wires within a chip. IUCF technicians ascertained that either the first wire or the fourth wire of each chip picked up noise from the other three wires, i .e. either wires 1, 5, 9 and 13 or wires 4, 8, 12 and 16 on each card showed most cross talk . It was also determined that the cross talk signal followed the original signal by about 25 ns . In the March 1988 run period we were able to control the cross talk problem by setting the threshold3 values of each card individually. Signals from consecutive wires are fed to five consecutive multiplexers (IUCF MUX) via a sixteen-line ribbon cable (total delay::::::: 210 ns), such that every fifth wire is connected to the same MUX. The IUCF Multiplexer is a single width CAMAC module which accepts 32 ECL-level differential inputs from two LRS 2735B wire chamber preamplifier cards or their equivalents, and a gate input (NIM) . During a gate, a fast OR output is generated and latched for the first event ( available at a front panel connector) . Events are also written into registers for CAMAC readout . Two of the three registers , A and B, are simple 16 bit registers , corresponding to the upper and lower 34-pin connectors on the module, respectively. Into these, events are latched directly during a gate . The third register , register E , provides encoded infor- mation about single or multiple events (bit 16) , module address (bits 6- lJ) and the address of th e high es t number wire being hit (bits 1- 5) . If no valid 3 Another indicator for insufficiently high thresholds is an increase in the observed number of so-call ed multiple hits , see Chapter 5. 155 V) - - - ~ - - - ft') - - - N - - - - - - - ~ i,.; I Q.. (.I ~f;; ~S~ ?~ .. ~~ ?"4 ~ 0 -~ \,\~ ~i~ -!. C nf&J' i ! .. - - - - Figure 3.4: W iring of LRS 2735b Printed Board 156 events have occured , all the bits are set to zero. To limit multiple events, the gate is internally shortened to a maximum of 33 ns following the first event. The m odule is capable to operate both in a normal or a fast 400 ns CAMAC cycle . All MUXs are gated by a Sl-S2-BUSY coincidence which is distributed by a 16-fold fan (Figure 3.5). The fan also provides a common START signal for the ten wire TDCs (LRS 4210) . An OR output from a MUX is discriminated (LRS 821) and serves as a STOP for its TDC. In March 1988 a sum of the five front ( and rear VDC discriminators, respectively) was used to form a coincidence ( see next section) . 3.6.3 Coincidence Electronics The coincidence circuit is shown in Figure 3.6. There are several inputs t o the coincidence circuit. One is the scintillator coincidence which has al- ready been discussed. The output register has two outputs: bit 1 is the run gate and bit 2 is set while the CAMAC is being read . When the run gate is off or the CAMAC is being read or the spin valid bit is not set (i. e. during spin flip) or in the case of a B-Hive alarm, an inhibit (INH) is generated in a logic fan (LRS 429A) which inhibits all the scalers (Event 10) , and via the scintillator coincidence all of the further regular event (Event 4) processing ( e .g . gates on the MUXs and STARTs on the wire TD Cs ). Also , a sci ntill a- t or coincidence via a gate and delay generator (EG&G GG8000) generates a BUSY signal and vetoes accepting any new events until processing of the old events has been completed. A BUSY signal can also be generated via 157 ,, , _.. -? -' I-+ t ~ ~ _.. - ~ ~ --+ -' f-+ -? ti} -- - ?- -- Q. - - 0 - tl - tl - - = --., __ - ~ -?- --? 1 1 ~ .. ctS ~ ~ Q ~ Q "-'Cl 0 8 8 c.-c I .... ~ '~? Cl> +-I ('IS ~ ~ 00 ~ ?_. .. ~ ... Figure 3.5: VDC Logic Circuit 158 veto St?S2 >< 1NH TT L r NIM DIS i s ------, C I I .....,_ I I ......_ I ..__. I -- Lo... G ~.... g, 11 1.!.11 I L!J 11 Fan R= "rn I I Va1. oq Pre- .::: Seal. "1 (!) w .O.'l ...... 0 c.n g_ co .... o. ar DC 0... ~ ~,___~ s ~t n , and B is the beam line transport matrix. In terms of the targe t transformation T = cos( a - ) / cos , the kinematic broadenin g fact or I< = ~ t governing the variation of momentum with scattering angle1 , and the dispersion matching fact or C = 8 Ell. .!!l!.... , the transformation Eq . ( 4.1) P 8 Po can be writt en m ore explicitly as ( 4.2) In this equation the s;1 and b;1 are elements of the transport matri ces S and B , resp ectively. The ij transport matrix elements are associated with the matrix 1 K is identical to the k factor fr om Section 3.4 .1. 164 elem ents of Section 3.4.1 as follows: 11 ---t (x I x) = M"' (magnification), 22 ---t (0 I 0) = Me (angular magnification) , 12 ---t (x I 0) (point-to- point fo cus) , 21 ---t (0 I x) (parallel-to-parallel focus) , 16 ---t (x / 5) = D"' (spatial dispersion), and 26 ---t (0 / 5) = De (angular dispersion) . T he angle 02 is defined by the angular acceptance of the spectrometer . When properly m a t ched , the coefficients of 00 , 50 and 02 vanish . The (momentum) resolving p ower of the matched system is then ( 4. 3) where the overall magnification is given as M 0 v = s11 b11 T - s16b21 I<. There- fore, the resolution of the total system is a functi on of J( and will usually becom e worse for large values of J( . Tuning the spectrometer such that the coeffi cient of 02 vanishes is done in the K600 with the K-coil ; this so-called kin ematic displa cem ent of the focal plane has been described earlier in Sec- tion 3.4 .1. Tuning the beam to eliminate the influence of the momentum spread in the beam on the image width restricts the dispersion of the beam line . From Eq. ( 4.2) we see that the coefficient of 50 vanishes if ( 4.4 ) For J( = 0, i .e. light particles on heavy targets , one recovers the well known disp ersion matching condition Dbcorn = - (D"' ) C ( 4.5) ]if"' spec T B ecause C and T are always close to uni ty 2 , thi s implies that the dispersion 2 In t ransmission configuration where = o. / 2, the ta rget transform a ti on T is exact ly un ity. 165 of the beam has to be equalized by the resolution 8 16 / 8 11 of the spectrometer. Finally, for a finite K value the beam line tune has to fulfill the condition -b12 = -S16 -J{ = L b22 ( 4.6) S11 T - ' called the kinematic defocusing of the beam at the target. The quantity L represents the defocusing distance . This step eliminates kinematic broaden- ing due to the angular spread of the incident beam by forming a correlation at the target between position and incident angle (see Figure 4.1) [Mar 83 , K600 L]. A prerequisite for kinematic defocusing to work is a convergent beam . Convergence or divergence of the beam, and also the beam angle and its temporal fluctuations , can be monitored to a certain extent with the left-right integrator asymmetry. Quadrupoles Q8, Q9 and Ql0 m BL 8 between the QDDM and the target are used to control both kinematic defocusing and dispersion match- ing. Also, the vertical spot size can be varied with Q9. For 120 Me V and 200 Me V beam energies extensive grid searches covering the space of relative changes 5Qi = !:iQ;/Q; ( i = 8, 9, 10) in the quadrupole strengths were per- formed . The result of these investigations was that in this space there is a more or less well defined "valley" where the beam is correctly ( de )focussed. Subsequently, one moves along this valley until the dispersion is matched. For this task we used a full target ( usually either a Au or Ca target) and th e three-hole hodoscope which was mentioned in Chapter 3. First , the correct K- and H-coil settings were verified by inspecting the slope and the curva- ture of the elastic line in an x 101 histogram without the hodoscope. Then, 166 OJ ~ 0 (4 .12) X = ( 0spcc + .60 + 13, for 0 < 0 176 c...o....o.. I '\. I I '\. I '\. I I '\. I I I I I..DI .. .......,. I I 0.0 I Q.) I -0 I '\. I c.o I I C\l I 0 f II \ I I CD \ I <] \ I I \ I I \ I I \ I I \ I t I \ / \ I I \ I I \ C\1-.:t' .I -+- / \ -- I I \ I I \ II / / 0.. \ I t:?1 / \ I / \ I I \ / I \ / / \ / I \ / / / \ / o co 0 0 0 0 0 -- 0 0 0 0 0 ID 0 I-D 0- l{) C\l C\l (..r s / qw) UP/ DP Figure 4.4: Determination of t he scatterin g angle? with the cross plot m ethod ; 0 ? is the spectrometer angle. T he dashed (positi ve angles ) and dot -dashed (negative angles) lines are fit s to the data points using the same fitting functi on . 177 it can be dem onstrated that the fittin g functi on fo r both posi tive and negative angles can be accomodated by y = a + b(/0,pcc + Ll0/ - 13) + c(/0spcc + fi0/ - 13) 2 . (4.13) The fitting parameters are a, b, fi0 and c. Imposing the same shape fo r positive and negative angles makes the fit robust even with only a fe w data points . A simple grid search program (GRIDLS , [Bev 69]) is used to optimize the p arameters . The fit to 4?Ca yields a scattering angle offset of 0.26?. A fit to 16 0 elastic data, on the other hand , yields a value of 0.40? which is probably too large. It is possible , however, that the asymmetry in angle of th e da ta set used in this fit is responsible for the discrepancy. The forward angle measurements for negative spectrometer angles were between - 10 and - 16?, while th ose on the positive angle side of the beam were between + 14? and + 18?. For the differential recoil method we first read the peak positions Pxa and Pxb of any convenient pair a and b of calibration peaks ( e.g. 16 0 O't and 9 Be 3/ 2~ ) from the summary file created by ALLFIT [Kel ALL] . Since the peak positions for our experiment are stored as momentum losses, the experimental differential recoil Llcxp can be easily calculated . It is simply the difference of the outgoing projectile energies E30 and E3b or , with the mass m and m omentum p1 of the incoming projectile, ( 4.14) Using the kinematical formulae in Appendix B , a computer code calculates differential recoils Ll( 0) as a functi on of the scattering angle and then mini- 178 mizes l.6.cxp - .6.(0)1 using a grid search. The method was used for many runs and a wide range of spectrometer angles. Subsequently, the scattering angle offset was determined as weighted average of the individual measurements . We found 0.14(7) 0 for the 100 MeV run in January 1987, and for the 200 MeV runs scattering angle offsets of 0.19(7)0 (April 1987) and 0.06(9) 0 (January 1988), respectively. Thus, it appears that the scattering angle offs et for Jan - uary 1987 found with the differential recoil method is smaller than the one found with the cross plot method. The reason for this is as foll ows: since the spectrometer magnetic fields are set for 160 kinematics and due to the finite horizontal angular acceptance , the Be lines appear slanted in x 101 ( the slope is a function of scattering angle and can be estimated from Figure B .2 in Appendix B) . The projection of a Be-peak onto Xf is weighted by its cross section angular distribution within the acceptance and, therefore, yields a systematically smaller peak position . Hence , the differential recoil method systematically underestimates the scattering angle. Over a wide range of angles the 9Be 3/2~ cross section angular dis- tribution can be approximately described by an exponential u(q) = ce - aq _ For 100 MeV one finds a = 4.26 and c = 1480.3, whereas for 200 MeV th e corresponding parameters are a = 3.88 and c = 735.1. To estimate the nec- essary correction to the scattering angle from differential recoil we evaluate the weighted average (q) = J qu(q)dq ( 4 .15) Ju( q)dq over the acceptance q0 ? .6., where 2b. = b.q is the angular acceptance ex- pressed in terms of momentum transfer and q0 is the central momentum 179 transfer . W 1' tl1 the approximations 3 sinh a~~ a~ + ?(a~) 2 e?all ~ 1 ? a~+ ?(a~) (l + xf1 ~ 1 - x, Eq. (4.15) becomes ~ 1 2 ~ 2) 1 2 1 3 q qo ( 1 - -6 a - -2 a~ + -12 a ~ 4 (4.16) ( ) . Evalua ti ng tlu .s expression for the parameters quoted above, we find 2 (q) ~ { qo(l - 0.7562~q2 ) - 0.5325~q + 0.4026~q4, (100 MeV) qo(l - 0.6273~q2 ) - 0.4850~q2 + 0.3042~q4, (200 MeV) . ( 4.17) menturn transfer is a function of the scattering angle and one can The mo 94 approximate this function for 100 Me V by q ~ 0.05 ? 0?? and for 200 Me V The quantity ~q in Eq. ( 4.17) can then be approximated by q ~ 0.06 . 00 .01 _ by (100 MeV) (4.18) (200 MeV) , ts m units of nuad . For q == l.Sfm - 1 and an aperture with a width where ~0 .. 0 of 1/ 2 I. ncl 1 , corre s ponding to a 17. 84 mrad hori.z ontal angular acceptance, 1 We gel from Eq. ( 4.17) (q) = 1.4978fm- 1 for 100 MeV ( (q) = 1.4957fm- for 200 MeV). Thus, the average correction to the scattering angle from dilferen? tial recoi.l should be 0.06' {or 100 MeV and 0.08' for 200 MeV, respecb vely With tl e correction we obtain therefore from dI' ff erenti:a 1 reco1?1 a scat term. g 1 al\g)e offset of t.0 = 0.20(7)' for the 100 MeV run in January 1987, which 4 1 is cons1?s t ent wi? th the cross plot value o f 0 ?2 6 f rom ?C a. Fo r tl e 200 M e V 180 runs w bt ? e O arn angle offsets of 0.27(7) 0 (April 1987) and 0.14(9) 0 (January 1988) . It was pointed out (G . P. Berg, IUCF, private communication) that 3 2 ? 111111 steering in the last quadrupole before tl1e target, QIO, causes an angle cl tange at t 11 e target of 0.1 ? (d.1 stanceq10- target = 183.88 cm). Tlie scattering angle offset is cliaracteristic for a particular beam tune and sl10uld not vary in time. However, steering in tl1e quadrupoles could make the offset time dependent. To investigate a possible time dependence we plotted tl1e original individual angle offsets (wl1icl1 were measured at different times) Versus tl1eir integrator left-right asymmetries ( which are a measure of tl1e beam angle on the Faraday cup). Tliis is shown in Figures 4.5 and 4.6 for t lle 100 MeV run in January 1987 and tl1e 200 MeV run in April 1987. The figur es s1 1 0w that in January 1987 tl1e beam was fairly evenly distributed over the left and right lialf of the split cup, implying a small beam angle at the target, while in April 1987 the beam was centered more on the rigl1t half (looking upstream), implying a larger beam angle at the target . This is consistent witli the larger angle offset observed in April 1987. However, th ere appears to be 110 obvious correlation between the scattering offset and th e integrator asymmetry, and 110 time dependence of tl1e angle offset. We believe, therefore, that it is justified to use an averaged offset. * * * At the end of the 100 MeV run in January 1988 (runs 946- 991) the encoder had an e1 e c t rom.c s pro bl e m causing a systematic offset of 3.4?. Until the encoder pro bl em was fi xe d , tl 1e spectrometer angle was set witl1 l1elp of 181 0 I- 0 p ~00 a 0 I o 0 LD a 0 41) 0 a 0 0 I- ~ ? 00 ,,--...._ 0:: a + 0 0 -~.._.. , 0 a D 0 ",,----..-..-_ D 0 D 0 D o of 8 DO 0:: 0 9 0 h 0 I -~.._.. , ["- co D o LD 0) 0 ~ I :>---. H (iJ ::i ~ (iJ I-:, ...-4 0 r--- (0 LD tj< (:) C\1 ...-4 0 0 0 0 0 0 0 0 0 Figure 4.5: Correlation betweeen the scattering angle offset and th e in - tegrator left-right asymmetry (January 1987). The diamonds denote angle offsets from spectra with spin-up, the squares angle offsets extracted from spectra with spin-down. 182 lD 0 ,,.--.... ~ + 0 i--.::i '--" ~ ,,.--.... ~ 0 0 I i--.::i '--" 0 0 ? ~ boo o0 o ? C lD ['- ? 6 ? co ? 0 0 0 0 e 0 0 0 0 I 0) 1 ? IJQO I ,-4 ? ? ?~- 0 0 00 ~ 0.. ? ? ., -- 0 (I.) = lf) ........ ~ 8 -acceptance. In the absence of a y-position chamber, vertical centeri11g of the im ? age 111 the focal plane was first checked by means of a pair of small, t liin "top" an d "b ottom" diagnostic scintillators w1 u ?c 1 1 over1 a ppe d ver t1? ca 11 y by about ?5 nun centered about the K600 median plane. Measurements of the scint"1l l ator coincidence yield versus verti?c a1 pos1?t 1?0 n o f be arn on t arge t (determined by the current of vertical steerer VT 5 in BL 8) for a small eutran ce aperture were used as an indicator for correc t ver t1? ca1 cen t err?n g 6 . In tl1 e course of these measurements, 110wever, i?t became apparent tl ia t tl ie optical alignment of the wire cliambers and the scintillators relative to tl1e llledian plane was off by about 1 cm and tliat the center of tl1e magnet acceptance did not coincide witli tlie center defined by llie detectors . For s ubsequent v er t1? ca l scans, tl1 ere ?o re, 1? t wa s decided to use a different method Where the ero ss sec t1? 011 o f t 11 e 12c 2+ s t a t e was measured as a function of the 1 5 p ro-~per -ve-rti-cal- ce-nt-eri-ng- on- t-he target is also i. mportan tr,o r ac curate char. ge measure- 11lents in th Vert" e Faraday? cups since ' like the spectrometer m a g nets ' t'h e dump pipe defin es a ical acceptance. 6 d Res u It of these measurements is a trapezoi.d al h ape,, the correct VT 5 current is then 5 efined b Y the middle of the plateau . 189 VT 5 current . B tl or 1ese measurements the spectrometer angle was cliosen to be 220 ' an angle w11 ere t11e 2! cross section is known to be fla t . *** th Wi li elp of a CH2 target we checked t11e stability of t11e 12C 2t cross sectio11 wi? t 11 respec t to ? acceptance ' ? computer live time . ' ? beam current (i. e. accuracy of charge integration), and ? elastic/ inelastic run (i .e. position on focal plane and rate dependence) . While the . .. sens1tiv1ty of cross sections to t11 e acceptance was tested in dedi- cated ru1 f, ls or both 100 and 200 Me V, dedicated rate and cliarge integration st udies Were done only at 100 Me V . At 100 Me V, t11e 1/ 2 incl1 diameter aperture (Al , 0.25 msr) was t11 e smallest aperture used for t11e acceptance test and 2 . . . . ) a lllch diameter aperture ( 4.0 msr, not 11sted rn Table 3.2 was the largest A . ? t 200 Me V the smallest aperture used for the test was the 1/ 2 rncl1 diainet . . er aperture ( A 1) and the largest was t11e 1. 6 111cl1 x 1. 6 111cl1 aperture (B5 ' 3 ? 18 l11sr ) . We found at both energies tJiat cross s.e ct1? 0ns measure d ? 1 w1t 1 Various . 1 acceptances were consistent within 2%. Therefore, no specia ac- Ceptanc e correctw. ns to our cross sectw? n results a.re necessary prov1'd e d tl 1a l Proper v t? er ical centering has been achieved. First, we found that 12c 2t cross sections from a sample of elas tic and 111elastJ?c spectra agreed within 3%. The elas tic spectrum was t a k en ?t1w1 1 a 190 l nA beam tl t . , le wo melastic spectra with an 11 nA beam. Furthermore, one inelastic spectrum contained tl1e elastic peak (higl1 rate) while in tl1e other the 1 . e astic peak was shifted bel1ind a copper block (low rate, different focal pla .. ne pos1t10n) . Second, we studied the cross section dependence of the 2+ 1 state as a function of both computer live time and beam current. For this t es t we used m. elasti.c spectra. In one samp1 e o f runs the live time Varied between 21 and 96% while tl1e beam current 7 for these same runs ' varied b t e ween 2.5 and 16.3. nA . Here we observed a total spread of 1.8% in the c . ross sect10n. In the otlier sample the live time varied between 51 and 76~0 1 . , w ule the beam current varied between 2.8 and 29.4 nA . rDo r t 1u .s sample , a smaller total spread of 1.1 % in the cross section was o bs erve d . It ap pears from these results tlrnt the accuracy of tl1e live time correction might b e s 11? g h t.l y more important. for tl1e correct cross sect10? 11 t 1r nn tl ie b earn current ? Cll arge 1. 11tegrat1. 0n seems to be faJ.r ly accurate iro r a 'd WJ e range 0 f beam currents. Off-line analysis of the 100 and 200 Me V production runs confirm d e these findings . Although the data rate for tl1e production runs was usually lower than about 300 Hz , our group studi.e d for a ?e w cases tl ie eJalle ct of the fast clears (run Period in March 1988) on the dead time for runs with high data rates (B. S. Fla1 1 d ers, Amen.c an Urn.v ers1. ty, pn.v at e com munication) ? It was found that the live time seems to be independent of the fast clear rate for rates Up to l kHz. In this region the live time correction wl1ich is aplied to tl, e 7 Avera____ _____ m of the left and right integrator s I ge beam currents are calculated from the su ca ers . 191 cross sect . 1 1 Ion s 1ou d be therefore reasonably accurate. However, fast clears do app ear to reduce the live time for rates in excess of 1 kHz. Based on some test cases, for 3- 3.5 kHz the dead time increases between 1 and 5%, for 3 4 - kHz by about 5%, for 4- 5 kHz between 7 and 10%, and for 8-10 kHz tlie dead tin . le lllcreases between 16 and 19%. 192 5 Drift Chamber Detectors 5.1 Introduction fhe K600 drift chambers detectors allow the accurate determination of an ncident particle trajectory by measuring the drift times of ionization electr ns with the help of appropriate electronics (see Section 3.6 .2 ). As an energe .ic incident particle ionizes the chamber gas along its track, it gen- erates positive ions which travel to the cathode planes and electrons which drift to the anode wires in the mid -plane of the chamber. The electrons -. .. . which are collected at the anode create a signal which is used as a STOP for -. the TDC associated with the wire ( we remember that the START signal is provided by a scintillator coincidence) . Figure 5.1 shows a typical drift time ?r spectrum for one of the multiplexers. On the software level , drift times are first converted into drift distances . Then, after the character of the chamber event has been identified, an appropriate algorithm computes the exact po- sition and angle of the trajectory in the focal plane (which coincides fairly well with the wire plane of the front VDC) . Finally, since certain classes of events (e .g. multiple hits), while not being analyzed, may contain good events, appropriate corrections of the final cross sections are necessary. The configuration of the (guard and sense) wires and the cathode planes is such that each sense wire defines a drift cell of 2.0 mm width and 12. 7 nnn length . Consecutive sense wires are separated by 6 mm . The electric fi eld is very uniform across the whole drift cell and only in the immediate vicinity of the anode wires and very close to the cathode plane do we find nonlinearities . 193 0 c.o ~ 0 ,q< ~ 0 C\1 ~ 0 0 ~ --lfl ~ J: -? 0 o:J , .. Q) s .-.?. 0 ?b- c.o .+-) ?~- '( ~ 0 Q ,q< 0 C\1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r-- c.o LO tj' C'J C\1 ~ +P / NP Figure 5 .1: Typical drift time spectrum; ea.ch multiplexer is associated with one such spectrum . The spectrum shown was ta.ken by illuminating the whole drift chamber uniformly. 194 If the electric field were exactly the same everywhere, we could just form the product of the drift velocity ( 46 .1 mm/ ? s) and the measured drift time (1 channel in the drift time spectrum corresponds to 0.317 ns) to get the drift dist ance. However , because of the nonlinear behaviour at both very short and very long drift distances, this method may lead to errors in the determination of the correct particle trajectory. Also, although for each chamber the relative timing of the drift times is easily adjusted by simply aligning the leading edges of the drift time spectra , there remains an unknown overall timing offset . For algorithms which involve the differences of drift distances ( e.g. three or more consecutive hit s) this absolute offset does not mat ter , but algorithms which include the sums of drift distances ( e.g . two-hit events) will be sensitive to the correct absolute timing offs et . An approach which implicitly takes care of the problem of absolute timing, as well as of any nonlinearities and inhomogenities in the chamber fields is the construction of a lookup-table or drift table which transforms drift times into drift distances. This table is based on the knowledge of the mea- surable maximum drift length , Smnx, which is equal to the distance between the wire and cathode planes, the total charge collected , Q, and the drift time distribution , dJ;' . After the drift time to drift distance transfo rm ation has been performed for an internally consi stent set of multiplexers, an absolu te timing offs et no longer matters because the shortest possible drift length is zero and the longest possible drift length is the di stance from t he cath ode plane to the wire. The details of the drift time spectrum in corporate all the non-linearities and inhomogeniti es of the chamber fields. For example, th e 195 st rong fi eld in the immediate vicinity of a wire accelerates a drift electron until it creates by ionization secondary elect rons which in turn may create more elect rons . This avalanche effect and the associated increase in particles collected at the wire is responsible fo r the spike at the leading edge of the drift time spectrum . The flat region of the spectrum represents the linear region of the drift cell . Finally, the tr ailing edge is not abrup t but is smeared out , in part because electrons with long drift distances may be lost (e.g . due to recombination , et c.) and not be collected a t the anode wire. If l : we assume that the ionization occurs uniformly along the track, the ... . verti cal axis of the drift time spectrum, Figure 5.1, represents a ( time de- ,. . ... . pendent) velocity d::. = d:. ~; .. . = cv(t) . Thus, integration of the drift time spectrum up to a time twill yield the corresponding drift dist ance s(t) ac- ?r cording to ?r.' t dN ' s(t) = c 1- dt' . (5.1) o dt' . I I' The constant c in this equation is c = Brno.x i Ntot , where Smo.x = 12 .7 mm , and where Ntot = Q / e is the total number of counts in the drift time spectrum . In Figure 5.2 we display graphically a drift t able, in this case for the front chamber in January 1987. Experimentally, the drift time spectra which are the input for a drift table are generated by illuminating the entire chamber uniformly using the high excitation energy continuum of some t arget . 196 0 c.o .-t 0 C\2 .-t 0 ,.----..._ 0 rJ} .-t .__~_., , Q) l : 0 OJ ?-6 ,.., ~ -.. +.-) n, ~ 0 c.o ?-~ Q ?r 'i 0 'tj< i I : 0 C\2 0 I.[) C\2 0 Figure 5.2: Graphical Representation of a drift table; note the deviation of the drift distance s(t) from linearity for drift times t below about 40 ns and above about 130 ns. 197 5.2 Classification of Events Before we can calculate the position and angle of a particle track in the focal plane we need to characterize the chamber event. Then the appropriate algorithm can be applied to calculate the desired information. To this end, one examines the MUX register E data words . As stated in Section 3.6.2, information is encoded as follows : ? the data word is zero if the MUX did not fire; ) : ? the data word is negative, i.e . bit 15 is set, if the MUX fired at least .. . ,. . twice; .. .. .. ? the data word is positive if the MUX fired exactly once; then the first five bits (bits 0- 4) contain the encoded wire number, the next five bits ?r: (bits 5- 9) the encoded MUX number, and the remaining bits (bits 10- 15) are all zero. I :' If any MUX register E data word is negative the event is classified as a multiple hit and rejected. Otherwise, the MUX ( and associated wire) with the shortest drift distance is determined, and a hit pattern is established by examining the adjacent MUXs on either side . We usually denote the MUX with the shortest wire by "O", the two MUXs on the left by "Ml" and "M2" , and the two MUXs on the right by "Pl " and "P2" . If n of the five MUX register E data words are nonzero , the event is called an n-hit event . T he number of hits a ray can make, i.e . the number of drift cells traversed by the ray, is a functi on of angle. As we can see in Figure 5.3, n decreases 198 ) ... +. ._ ________ :a ~ t t +-- -=- Figure 5.3: Extremum rays for n -hit events ; d = 12. 7 mm is the spacing be tween the cathode planes , s = 2.0 mm is the width of a single drift cell. Both the minimum and maximum angles increase with decreasing n . 199 with increasing angle . With the cathode spacmg, d = 12 .7 mm, and the width of a single drift cell , s = 2.0 mm, the minimum and maximum angles for an n -hit trajectory with the wire plane are 0~~ = arctan ( n! ), and 3 2 0t2x = arctan ( n~ ), , respectively. This is also summarized in the following 3 4 table [K600 L] . n 2 3 4 5 0min 38.4? 30 .0? 24 .4? 20 .5? 0max 72.5? 51.8? 32 .4? 30.0? J Our calibration for 0tgt gives an angular magnification of about 1. 7 (see Section 4.2), and RAYTRACE calculations (see Appendix C) yield for central (in 0tgt) rays with various o's the first order relationship (5.2) where x I is in units of mm , and 0I is in units of mrad. Because of the slope in 01(x1 ), apertures with 0.5, 1.0 , 1.6, and 2.0 inch width, corresponding to horizontal angular acceptances of 17.8, 35. 7, 60 .0, and 71.4 mrad , define slanted windows in an x 10 I histogram of 30 .2, 60. 7, 102.0, and 121.4 mrad width in 01 , respectively. If we look at the focal plane region of 200 mm < x 1 < 800 mm, where most of our data are taken , we find that the various acceptances cover the following angles: Aperture 0.5 in 1.0 in 1.6 in 2.0 in 0min 32 . 7? 31.8? 30.6? 30. J. O 0mox 38.5? 39.4? 40.6? 41.2? 200 From this t able it follows that while 5-hits should be relat ively ummpor- t ant, 2-hit events will become increasingly important for large x 1 , i.e . high excitation energies, and large scattering angles. Events that make only a scintillator coincidence (0-hits) or one hit in either chamber (I -hit s) are most likely due t o background and are not analyzed . Indeed, in March 1988 0-hits were eliminated altogether on the hardware level by the fast clear coincidence circuit which was described in Section 3.6.3. The particles which traverse a drift chamber a t an angle to the anode plane usually produce a cluster of firings as they cross over several wires . l The low-energetic drift electrons involved are produced in "grazing" atomic collisions (primary ionization) . Additionally, high-energy electrons, so-called o-rays , can be form ed in "knock-on" atomic collisions. These high-energy electrons traverse the chamber and can produce fresh electrons and ions as well (secondary ionization) . Those events cause multiple firings elsewhere in the chamber and have t o be distinguished from the original cluster which carries the real position and angle information for the incident track1 . In hardware, additional multiple firings can be limited to a certain extent by choosing the gate width of the MUXs appropriately. As mentioned in Sec- tion 3.6.2, for this we internally shortened the gate width to a maximum of 1 The proba bility for another valid event to occur simultaneously to the fir st event. is sma ll : with the usua l cyclot ron pu lse period of 33 ns and with a typical event rate of 300 Hz we find a proba bi lity of 9 x 10- G fo r one event per pul se. T he probabi li ty for two real events to occur in one pulse is thus 8.1 x 10 - 11 , corresponding lo a rate of 2. 7 x 10 - 3 Hz. The rate of true simulta neous events is fi ve orders of mag ni t ude sma ller and therefore negligible. 201 33 ns following the first event . Other, less important mechanisms to generate firings of chamber wires , which are unrelated to those from the primary ion- ization, are pick-up of noise by wires ( e.g. discriminator threshold too low) and , to some extent, ionization or pair production by background photons . For a regular event which causes only one cluster of wires to fire, all the wire numbers in the cluster should be consistent with that of the shortest wire . Additional wire firings due to 5-rays, pick-up, or photons that occur somewhere else in the chamber but at the same time, can cause a MUX to ) : fire twice. This kind of event is called a multiple hit and bit 15 in MUX ... register E is set; we don't process these events further and only correct the .. .. final cross section by a factor which represents the probable fracti on of good events among the multiples . Since the probability for multiple hits is propor- tional to the amount of background present, we call this correction a clutter correction . In the case of an accidental coincidence where no MUX is firing I' more than once, the wire numbers of the extra cluster are inconsistent with the ones of the good cluster . We call these events extra hits and we do cal- culate position and angle for most of them , assuming that the shortest wire is part of the good cluster. This assumption is good for the majority of the extra hits 2 . In the analyzer code the character of an event is represented by a hit pattern. The hit pattern is a ten bit word (bit s 0- 9) , where bit 2 always 2 Most extra hits a re caused by 6-rays. Since the extra cluster is due to electrons fr om the secondary ionization, it occurs later in time than the good cluster which is du e to electrons from the primary ionization. 202 represents the shortest wue and is unity, and where bit 7 is always zero. While bits 0- 4 are reserved for MUXs which have "consistent,, wire num- bers , i .e. wire numbers which are within ?2 of the shortest wire, bits 5- 9 are reserved for MDXs with "inconsistene1 wire numbers . As an example, let us consider a 3-hit event for which MDX n ( and wire m) is the MDX with the shortest short est drift dist ance, and where the adj acent multiplex- ers MDX (n - 1) and MDX (n + 1) fired also. Further , let us assume that the encoded wire number of MDX ( n + I) is m + 1 and thus consistent , and l : that the encoded wire number of MDX ( n - I) is l = m - 5k - 1 ( k 2: 1 and integer , l 2: 0) and thus inconsistent . The hit pattern for such an event would then be ~9 ~8~ ~7 ~6~ ~5 .,4. ..3 .._2 _1 ~~0 0 1 0 0 0 0 0 1 1 0 . ? r ~~ ~~~~~~~ M2 Ml Pl P2 M2 Ml O Pl P2 accidental hits regular hits This very comprehensive pattern word was, however, used only for diagnosti c . I: purposes . The streamlined analyzer code which was employed for production data replay utilized a simpler pattern word in which only the Ml and P l wires and the lower five bits of the pattern were used , and no bit was set for inconsist ent wires. The resulting pattern word was thus always of the fo rm 0xlx0, where x = 1, 0. The above example would be represented by the pa ttern 00110 , which means that this 3-hit event with an in consistent wire would be treated like a regular consecuti ve 2- hi t event . With a diagnostic analyzer and tes t package we examined several runs from the various run periods. We found that the great majority of event s (usually about 95%) were always events that made 3 hits or more. However , 203 we also found that generally over 80% of all the 5-hi ts were comprised of a 4-hit and an accidental coincidence with an inconsistent wire . T he number of 0-hits and 1-hits was observed to increase with background . But, while the fracti on of 0-hits in some cases could be up to about 70% of all scintillator coincidences ( one of the reasons for developing the fast clear) , the fraction of 1-hits stayed always below about 1.5%. The fraction of non-consecutive hits (e.g . patterns 10101 , 01101, 00101, etc .) was found to be generally less than 0.5% . Between 1 and 2% of all events were 2-hit events, becoming ) : I more important at large x f and 0f . This was found by a grid in x 101 ( see ? I _,.,, I Table 5.1) . Omission of the 2-hit events (Figure 5.4c) leaves "holes" in the .- . 'I ., : : x f spectrum ( see Figure 5.4b ). Because of the periodicity of the holes , a r I global correction of the effici ency is not possible. We also found that the ?r: probability of losing a wire, thus making a 2-hit out of a 3-hit or a 1-hit out of a 2-hit event, is very small . Therefore, 2-hits are real events with a. steep I '' ' angle and should be included in the efficiency. On the other hand , sin ce 1-hit events are not generated by 2-hit events, they are true background events ( e.g. due to the beam or the Faraday cup) and should not be included in the efficiency. The fraction of multiple events generally stayed below 1.5%, while the fraction of extra hits was often between 2 and 3%. This is a somewhat surprising result since most of the hits are 3-hits or more. The probability for an accidental coincidence to fire th e same MUX twice, and th erefore make a multiple hit rather than an ex tra hit , should be more than 60% for th ese types of events. As mentioned before, extra n -hit events usually have only one inconsistent wire and therefore can be treated like an (n - 1)-hit . 204 ::::i ~ - si::: ;-:?. r~: i ~e:.. O"" ..., '-' ,(D; -::::i ? (l i-~- (0 ::;- c;, .0c.. ... ,; r!~; ;c...n.. ,~, ct, --~ :.::,:.i ..c:,::q:i ~~ C) u, ,; <+ H C~./"J. -'-1 ..... c..? Thetaf/ xf 2000 - 3500 3500 - 5000 5000 - 650 0 6500 - 8000 8000 - 9500 channels Ill =~ ~o? =- ? ===---===================-------==============-===-==----==-=====================----------------R-- 665 - 725 96.47 +- 7.19 9 7 . 8 6 +- 1. 8 6 98.44 +- 0 . 84 u,0-,::::,H 60 5 - 665 98.24 +- 2.17 97.90 +- 1.11 97 .35 +- 0 . 81 97.30 +- 0.61 efficiency ~ 545 - 605 98 . 28 +- 1.69 98.31 +- 1.12 97.86 +- 1.10 97. 78 +- 1.17 ( % ) Q:)~~ ~-':: .__ 485 - 5 45 97.54 +- 5.29 97.98 +- 4.04 96.30 +- 8.84 ~ ::,- "::;--' ...... ===========================-===-=======================--====================== 66 5 - 725 1 .0 9 +- 0 . 61 0.45 +- 0.09 0 . 33 +- 0.03 - ;..;.:, :. tv 0,; 605 - 665 0.12 +- 0.06 0.29 +- 0.04 0.32 +- 0.03 0.36 +- 0.03 bent hits Cb (b ... ' 1-1 545 - 605 0.04 +- 0 . 03 0 . 12 +- 0 . 03 0.17 +- 0.03 0.23 +- 0 . 04 ( % ) .... ~ w i::: 48 5 - 545 0 . 14 +- 0 . 2-1 ~ ~ ... ? ~ 66 5 - 725 13.32 +- 2.04 13 . 0 7 +- 0 . 51 17.19 +- 0.27 tv ::::,S~c.n o :::..cr::::i c.n 60 5 - 665 1.84 +- 0 . 21 1 . 67 +- 0.10 2.95 +- 0.10 3.39 +- 0.08 2-hits CJ1 v ~ C..G) 545 - 605 1.81 +- 0 . 17 0 . 55 +- 0.06 0.94 +- 0.08 1.01 +- 0.09 (%) ~ ,; ~ ,.-._ 485 - 545 1. 01 +- 0. 41 0.17 +- 0.15 0 2..;. ~ ===========================--=----------=====-==-=--------------==-================================ 66 5 - 725 82.34 +- 6 . 40 84.83 +- 1.67 80 . 98 +- 0.73 ...... - ? 0 605 - 665 93.01 +- 2 . 08 86.33 +- 1.01 83.86 +- 0.73 83 . 52 +- 0.55 3-hits tv ~~Ill ~ :=- .... 545 - 605 7 8 . 4 6 +- 1. 4 4 58.97 +- 0 .78 55.92 +- 0.74 56.58 +- 0.79 ( % ) :::. ~...:it--:> 485 - 545 44.49 +- 3 . 06 27.97 +- 1.74 25.93 +- 3.69 t:""1"- en i--- 0 ============================--------=-=======-==-=---=--=====================--=========-===== u, ..., 0 66 5 - 725 2.72 +- 0 . 91 1. 60 +- 0. 1 7 1.43 +- 0.07 ~ ~ 60 5 - 665 4 . 6 4 +- 0.34 11.50 +- 0 . 29 12 .6 7 +- 0.22 ~ := ~ 12.57 +- 0.17 4-hits c.. 54 5 - 605 19.05 +- 0.58 39.60 +- 0.60 42.2 3 +- 0.61 41.43 +- 0.64 ( % ) ...,.. si::: ~ < 485 - 5 45 52.90 +- 3.43 70.18 +- 3.17 72 . 8 4 +- 7 . 2 2 --- - - --- - - - =' - O"" - Thetaf/ xf 2000 - 3500 3500 - 5000 5000 - 6500 6500 - 8000 8000 - 9500 c hannels .... ~ ~ ==========================---=== 00 o II c.. ;:; ~ ~ e-' ~ -: ~co ~~ u, C~J'J ~- ? (b 3, ,; (l ~ c'ii" ...:i ~ = - u, (l (b ~ :< ....... 0 0 0 0 0 0 0 0 0 0 0 N00 0 0 0 0 0 0 oo n 0 0 0 ('I') N rl ?II'\Z II_, ('I') N .... O\o-Cle2: r-'--;;~e::=!:::=---7 ~~ ol-0 oHC"'l ? . 0 -rl ?'~ Z~11 ~ C0::>0 0rlll)ct 0 II'\00 COZO\\O Hf('I') I-? ? XUCO O' -'\Ori Cl~ xO 00 .JJ 0~ II'la......::xn "ti L _ ___- ---=:!!l!!~=-------Lr--xco- "?? I 0 o 0 0 0 0 0 00 0 0 0 0 0 0 N00 .0.. . 0 00z 0 0 0 0 Ir\ ?0Hll 11 co \0 ~ N .-----L----__.J'---------t-rl 0-' I _J <.u....... t-~ ?r. ~CO ? . ~ ~ 0~ I:' 0 000 II'\ZO\\O >HIN Cl t- ?? XUO X OII'\ .-4 I .. rlO N ::.:: -'\Ori ~ CilLf'C) Ll"1fN ~ Cl 0 0 - ~ t:lZI- u L__c_ ___________. .L.o~ -=! Figure 5.4: For run 556 we display in a) and b) the Xf spectrum for 3 or more consecutive hits . In c) we display the same spectrum for 2-hits only. In d) we show the spectrum for 2 or more consecutive hits . 206 5.3 Calculation of Position and Angle In the following, we will denote the interpolated fractional wire spacing by f and the (one-plane) slope by a. With the wire spacing s, and the shortest wire number n , the position and angle in the focal plane can be expressed as x s(n + f) 0 arctan a . ( 5.3 ) ::t : I .... . j The track position in the front chamber is always the position which we quote -..?. . .,i .I ' as x I. The focal plane angle can also be calculated as two- plane angle from . ' the track positions in the front and rear planes (xF and xR), the relative r, offset between the two planes (L'.ix) , and the distance between the two planes . r, (z). We get '' '' = z 01 arctan ------+ (5.4) ' I' XF llX - XR It is this two-plane angle which is always quoted as 01 . For a good event , however, we require consistency between the two- plane and one-plane angles. The most important classes of events are those which make three of m ore consecutive hits . All of these events have the pattern xlllx, where x = 1, 0. The calculation of position and one-plane angle for such a track is based on the drift distances dM 1 , d0 and dp 1. As Figure 5.5a shows , th e trajectory can pass either between the Ml and the 0 (xl.llx) , or between the 0 and the Pl wire (xll.lx) . We find for the xl.llx case f - _l dr1 - dM1 a = ~ - 2 dr - do ' . ( 5.5) ) 1 207 ~ . ! ~ . 1 -..-, :'\ ?, M.,? u > \ I: I: 0 - 0 ~ 0 ~ ~ 0 0 0 i 8 0 0 0 _-; - ,,---.."' - - () :a ~~\ ...... :a :! : I ~ . i ? I ;;: I \ '\ M -;-;;: I ...,? ..., .~ .a ? I u 1:1 1:1 0 0 . ' :~ 0 ~ ~ 0 ~ ~ ~ . I : : ;; ;; :a . -- -0 0 r, :o-~ 0 0 '? ~ . r, I ': .,, I 0 ;-; ___ .., __ _ Figure 5.5: Event types: a) consecutive 3-hit events; b,c) consecutive 2-hit events; d) recovery of 2-hit events via two-plane consistency; e ,f) asymmetric 3-hit events (bent rays) . 208 and for the xll.lx case a = ~- ( 5.6) ? Another very important class of events are consecutive 2-hits (patterns 00110 and 01100) which have to be included to ensure a flat effici ency in x 101 . As before , for each case we have the two possibilities that the track passes left or right of the shortest wire (see Figures 5.5b and 5.5c). In con- trast to 3-hits, however, the positive identification of the left- or right-case is less straightforward since two driftlengths are insufficient for unambiguously :;[ : I ? ? ? I determining their relative sign . Intuitively, it is obvious that most consecu- -?II I . ' ,,- ? I tive 2-hits will be of the type 001.10 or 01.100, rather than of type 00.110 ?? If I or 011.00 because of the steep angle required for a true 2-hit . Events for r, . r, which the track passes outside the cluster feature smaller angles and should have been 3-hit rather than 2-hit events. Indeed, it was found that the ma- . jority of 2-hits are are of the interior type . We believe that the 2-hits of I '' the exterior type are probably due to the loss of either the Ml or Pl wire of a potential consecutive 3-hit event. We calculate position and angle for consecutive 2-hits as follows: for the 001.10 case we use a = ~ . ( 5. 7) ) and for the 00.110 case f - ___ql[__ a = ~ - ( 5.8) - dp 1 - do ' ? For the 0 1.100 case we use a = ~ . ( 5.9) ) 209 and for t he 011.00 case f - ~ a = ~ - (5 .10) - dM1- du ' ? We can identify the appropriate 2-hit case in two ways: t he fi rst way uses two- plane consistency while t he second method employs the one- plane slope . In the fi rst method one calculates the projected posit ion in t he other plane for both the left and the right case of a gi ven 2-hit pattern (rays I and II in Figure 5. 5d) . The correct ray will mini mize the difference bet ween the crude position (i. e. the shortes t wi re ) and the projected position in the other ;t : I ? ? I plane . For example, let us consider the 01100 pa ttern from Figure 5.5d . .-? ? I ' ?? ? I If we assume typical values for the dM 1 and d0 drift dist ances of 6 mm and .-? .? I ' r, 2 mm , respectively, we find for ray I ?r 'I m? ? = i. e . m - ~~ 13 (5.11 ) dM1 + z dM1 + do ' - d Ml + d fl ~ ' and for ray II m? = ? i. e . m = ~ ~ 26 (5.1 2) dM1 +z dM1 - du ' dM 1 - do ' i .e . the two projected positions differ by 13 wire spacings. The correct ray can therefore be easily identified, even if only the crude position in the other plane is available for comparison . The other method for identifying whether t he track passes l ft or right of the shortest wire m akes use of the fact that if, fo r example, a 00.110 type event is treated like a 001.10 event , the calculated one- plane slope will increase . That thi s is indeed the case can be seen if 011 e compares the slope in Eq . (5 .8) , which involves the difference of d p1 and d0 , with the one in 210 Eq. ( 5. 7) , which involves the sum of the same drift dist ances . Assuming again 2 mm for a typical d0 drift length , the difference of the two slopes, Eqs. ( 5. 7) and ( 5.8) , is ~ ~ 0.67 which corresponds to 588 mrad or 33. 7?. Figure 5.6 shows the one-plane slope (times a fact or 1000 ) calculated from Eq. (5 .7) . The 001.10 events comprise the large peak. The 00.110 events which are treated like 001. 10 events are responsible for the long t ail on the large-slope side of the peak (beyond about channel 875) . It is evident that here the interior type constitutes the majority of all 00110 events . The same can be shown for the 01100 case: for most of the 2-hit events the track lies between the two firing wires. The same conclusion can be drawn from the next figure, Figure 5. 7, where we compare the calculated drift length dM 1 for 00110 events with the corresponding measured drift length for consecuti ve 3- hit events . Most of the calculated drift lengths are very large, whi ch is consistent with the steep angle of the 001.10 case. The 00.110 case which features a smaller slope would require small dM1 drift lengths . 211 0 0 0 N 0 0 l.() ~ (/) ......,...J. ,--.._ ..c: :t : I l.() ,c 0 .. 0 ['-- (.) ~ ro 0 ..__ 0 ~ ~ Q) ,... ." : ~ . : 0 ..---( r, (/) . r : 0 0 LD I ': 0 0 0 0 0 0 0 0 0 0 l.() 0 l.() 0 0 l.() -tj< (:J (:J N N ~ s1uno;) Figure 5.6: 2-Hit recovery by examination of the one- plane slope; if a 00.110 event is treated like 001.10 the slope increases by a significant amount . The slope shown in this histogram is the slope from Eq. (5 .7 ), multiplied by a factor 1000. 212 CX) ,.....-...._ lD s s -.._.,, ::.t: ., . I tj< Q) () .. . ~ ... ' co . '' ...? ' if) C"J . ........ r, Q . r : ...? 4.-...-....?. C\l S--! Q I '' ' 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 lD 0 lD 0 lD 0 lD ("') ("') C\l C\l ...-i ...-i s 1-unoJ Figure 5 . 7: Comparison of the calculated drv1 1 drift length for a 00110 event with the corresponding measured drift length for consecuti ve 3- hi ts . Most of the reconstructed 2-hit drift lengths are very large , indicative of the steep angle which is characteristic fo r the 001.10 case . 213 5.4 Drift Cell Resolution- Straightness of Tracks For the case of symmetric consecutive 3-hit events (see Figure 5.5a) two interesting quantities can be derived : first, as mentioned before, if no drift table is being used the knowledge of the absolute timing offset ~ is important for any position and angle calculation which involves sums , rather than differences of drift times t . One finds (01.110) (5.13) (011.10) . '..t.: I , When one histograms the quantity ~ one finds a Gaussi an-shape distribution , . , ... : with a certain width, the centroid of which represents the absolute timing ' .. : offs et. The width of the distribution , on the other hand , is proportional r , . r : to the intrinsic drift cell resolution . This resolution is found to be about 0.25 mm . For the case of asymmetric consecutive 3-hit events (pattern 001. 11 or I :' 11.100) one can study the "straightness" of the track (see Figures 5.5e and 5.5f) . Testing the straightness is equivalent to testing the internal consistency of the measured drift lengths . Especially, we want to study the reliability of the very long drift lengths . For a straight 001.11 (11.100) track, typical values for dp 2 , dp 1 , and d0 (dM2, dM1 , and d0 ) drift lengths are 6, 2, and 2 mm , respectively. These values yield a typical focal plan e angle of 0f = 588 mrnd. Th e working assumptions in the following analysis are that ? the drift length d0 associated with the shortest wire is cor rect; ? the particle track crosses the wire plane within the cluster , i.e. we have 214 the cases 001.11 or 11.100; ? together with the shortest wire a. consis tent wire reproduces the "bench mark" angle of 588 mra.d , while an inco nsistent wire does not . For the case of a. straight 001. 11 track the quantity o = dp 2 - 2dp 1 - d0 vanishes. If o < 0 the track is bent and convex, while for o > 0 it is bent and concave (see Figure 5.5e) . The convex case a.rises if either dp 2 is too short or if dp1 is too large . The concave case, on the other hand , occurs if either dp 2 is too large or If dp1 is too short . In order to identify the inconsistent wire ?? ? I we have to form , as we have indicated above, separately the one-plane angles ,. . ' :. I: tt ? I of dp 2 with d0 , and of dp1 with d0 . We do this by evaluating the quantities 11 1 I . r, a = 18 - dp2 - dol and /3 = 14 - dp1 - dol - In the case that a > /3 we can ,. . ' identify dp 2 to be the inconsistent drift distance; from a < /3 it would follow that dp1 is the inconsistent drift length . ' Analogously, for the case of a. straight 11.100 track the quantity o = I : dM2 - 2dM1 - d0 must vanish . For negative o the track is bent and concave, for positive o it is bent and convex (see Figure 5.5f). The concave case arises for either a dM 2 that is too short or for a. dM1 which is too large. The convex case occurs if either dM2 is too large or if dM 1 is too short. Here we form the quantities a = 18 - dM2 - dol and /3 = 14 - dM1 - dol- For a > /3 the drift length dM2 is inconsistent, whil e for a < /3 it foll ows that dM 1 is in co11 sistent. We histogramed the quantity o for a.symmet ri c 3-hit events and found it to be predominantly positive for both 001.11 (i .e . concave) and 11.100 (i.e . convex) events . Additionally, for these cases it was found that genera.Uy 215 the outer wires P2 and M2 were the inconsistent wires and that their drift lengths were longer than they were supposed to be. It was also observed that the frequency of occurence for bent rays increased with x 1 and that it showed a certain periodicity which sugges ts that there is a possible connection with 2-hit events . If, for example, the P2 or M2 signal were due to pickup , the associated drift length will be inconsistent with the ones that are caused by the incident particle track. A similar analysis for symmetric consecutive 3-hit events demonstrated that the Pl and Ml drift lengths produce reasonably t : I straight tracks . ? ? I .. ' ' 5.5 Summary and Conclusions r, We can summarize the major results of this chapter as follows: ?r : ? it is sufficient to consider only consecutive hits. ? the long drift lengths associated with the M2 and P2 wires are oft en I :' inconsistent and , therefore , should not be used for position and angle calculations . The Ml and Pl drift lengths, on the other hand , yield reasonably straight tracks . ? if 5-rays are the predominant mechanism for accidental coincidences with an inconsistent wire, we can assume that the shortest wire is part of the good cluster. We can then treat the n -hit event with the in con- sistent wire just like an (n - 1)-hit event where all wires are consistent . ? we correct the final cross section for multiple events by a global fact or (1 + /multi) , where fmulti is the fraction of multiple events . Sin ce th e 216 number of multiple events seems to track with the overall background we call this correction a "clutter" correction to distinguish it from the intrinsic efficiency of the chamber. ? a similar global correction for 2-hit events is not possible because of the x J and 0 f dependence . Without the ( significant number of) 2-hit events the efficiency surface in x1B1 is not flat and has holes . V,/e have means to resolve the left-right problem which is characteristic for 2-hit events and are, therefore, able to include them in the efficiency explicitly. .t:. ? we require from a good event that it ... : 1. passes the particle identification test; r I 2 . is not a multiple event or background event ( usually 0-hit or 1-hit ); . r : 3. is not an event due to beam halo or slit scattering which can be ' discerned by examining the angle a.t the target ( see next chapter); I : 4 . allows the accurate reconstruction of the focal plane angle. Here we require that the two one-plane angles as well as the two-plane angle are all internally consistent . ? We define our efficiency c to be the fracti on of good events that have additionall y a good hit pattern , i.e. events which make at lea.s t two consecutive hits . T he contribution to the effici ency of events which are not included in this definition, e.g. certain classes of non-consecutive or extra hits, is negligible. With this definition , the effici ency was generally between 95 and 100%. 217 5.6 Some Diagnostics We developed some useful diagnostics to identify problems with the discriminator thresholds on the preamp cards ( see Section 3.6.2): ? if all the discriminator thresholds are zero, every chamber hit becomes a multiple hit ( example in March 1988). ? during the development run in September 1988 the threshold of one single preamp card was too low, producing what was long believed to t : I be a "hot" wire . Certain wires of the card were picking up noise and appeared, therefore, for most events as the shortest wire . Additionally, . : . : however, the adjacent wires were misidentified . When the chamber is r. illuminated uniformly, this feature can be seen in a plot of the the short - . (: est wire versus the M2, Ml , Pl, and P2 (extra) wires (see Figure 5.8) . Normally, shortest and extra wires are distributed uniformly among . I : all the wires , yielding the diagonal lines in the figure. The fact that certain wires fire more often than others, together with their adjacent wires being misidentified , explains the off-diagonal "hot spot" . ? cross talk between Wifes (example March 1988) manifests itself, de- pending on the individual thresholds , on all the cards . This leads to a more or less pronounced peri odic st ructure whi ch can be observed in any spectrum for inconsistent wires (see Figure 5.9) . The cross talk can be removed by adjusting the individual thresholds of the preamp cards appropriately. 218 -- 0 > ... ... Cl ...... 0 0 Do 0\ II\ >- ('11 ...... ...... ...... 1-.-.- -----~------ -~-------~---------i- N ....... .. . - ~ I ?CJD ?o ?II H z . . ?u.J'IIO ?? 0 ? ? 0 ?o ~. s: ~...... . ?co 0: ? II ?"' . ?? ?? ? .. ~I V I ? N ?? V ??? .. ~ :::'cQ' l I 0 ??I I? 0 Cl(_). ..... 0 II? + ??.. . O\~ w II x';:F 0 ?II .. '--(/'\ 0 0 II? ...... ?? 0 I. C ll . . ... .. ?? 0 . II ?? .z... . ??. . . _J . II ?? ??I. I ... .. ?.? . I ?? I ?? .. . .. I I.I . ?I??. .. .. ??. . ...... II ?? ? II I. I . ?? ? ? ? ?? .. ?II 0 ? I.I. . ??. co . ' - ... .. ... . . fl II ~o \0 0 II I . .. 0.--1(/)- ?? I? .-I I .. ?. ... .. . 0 O\r---II\ . '::.:: . I I ? 0~ ?? . .,. ? x~' .,..,___,:_;_J ____________________________??_? I I _ 01..&...Zf->- ('11~~ Figure 5.8: Diagnostics for a "hot wire" which is caused by the corres pond- ing preamp threshold being set too low. The figure displays the shortest wire versus its ( extra) adjacent wires . Since the adjacent wires of th e shortest wires with the noise problem are misidentified, they appear off-diagonally. 219 I ' 0 CD ,--l ....., I 0 'tj< ,--l I ::r: 0 C\1 I ,--l I c.:, 0 I 0 h ,--l Q) [:,;.. ,D I 0 6 co ;:j Ci] z I - Q) t 0 h Q CD I ?~- u 0 I 'tj< 0 C\1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 C\1 0 co CD 'tj< C\1 ,--l ,--l Figure 5.9: Diagnostics for cross talk; the wire spectrum of any ( extra) wire will display a periodicity due to the individual preamp cards (A- J) . 220 6 Data Reduction 6.1 Replay Our data were replayed under the Q-system. The analyzer, as well as the test- and histogram-setup files were streamlined for speed and incorpo- rated many of the results from the previous chapter . Several important cuts were applied to the data during replay. The particle identification (PID) cut and tests for multiple, zero- and one-hits in each VDC plane were hardwired t : I in the analyzer. ? ? I .. The PID cut is made on a two-dimensional histogram of the geometric . 'I ? .? I ' mean pulse heights J SlN ? SlP and JS2N ? S2P and we eliminate with it r, deuterons, reaction tail from the scintillators, and general backgound. The . ( ; analyzer also examines the MUX register E data words for multiple hits (bit 16 set, i .e. the data word has a negative value) and for zero-hits (all bits J :' zero, i.e . the data word has a value of zero). If an event does not have a good PID or if it is a multiple hit or if it does not make at least two hits in either of the two planes , further processing halts and the next event is processed . The cut on the difference of the two one-plane angles ens ures consistency and correctness of the position and angle calculations for each chamber. Finally, a cut on the reconstructed angle at the target 1 , 0tgt , was necessary to remove from position spectra backgound du e to slit scattering (mainly for elastic spectra) and to beam-halo (mainly for inelastic spectra at 1 In the convention used here 0tgt = - 0,catt ? 221 forward angles) . During the early 1987 runs , the long low-momentum tail of the beam extended out to the beam pipe walls and caused there a halo which, because of the special geometric configuration at forward angles, reached the spec- tromet er acceptance and appeared as significant background in the spectra ( c.f. Figure 6 .1 ). Due t o the large dist ance from the beam pipe p ort to the spectrometer entrance, halo events generally make very small angles with the beam axis and, therefore, always appear under a smaller (less negati ve) scattering angle than real events from the target at p ositive (negative) spec- ? ? I trometer angles 2 . Halo events can be seen as a very distinct feature ( c. f. ' ..' ' .. '' Figure 6 .2) in the 0tgt spectrum, and can easily be separated from good r, events . At p ositive (negative) spectrometer angles they will have, with our r . sign convention, negative (positive) 0tgt values. Slit scattering can oft en also , . ' ' be easily recognized ( c.f. Figure 6.2). Assuming the cross sectional angular I '' distribution of the aperture material (brass) falls very steeply over the angu- lar range of the aperture at forward angles, the intensity of slit scattered rays coming from the right (left) edge of the aperture will be much higher than of rays scattered from the left (right) edge for p ositive (negative) spectrometer angles ( c.f. Figure 6 .3) . Scattering changes the direction of the rays t oward s larger (more negative ) scattering angles for positive (negative ) sp ectromete r angles . Hence, they appear as a pedes t al or tail on the negative (positive ) 2 A simple geometric argument shows that th e ha lo a ngle would a lways be exactl y ha lf of the spectrometer a ngle if the ha lo originated on the beam-axis at the entran ce to th e scattering chamber. 222 - ~-- side of the center peak, the good events, in 0tgt ? 223 Positive Spectrometer Angles Negative Spectrometer Angles +- I --? Beam .... axis Halo events ~ (Jq .:: '1 /'ti 0) I..- ' IJ:l Pl (l Scattering ::,;" O,.Q., Chamber tv tv 0 ~ C =0.. 0.. .:: (..b. . 0 cr" (b Counts Counts sPl ::r- Uk low momentum Beam Pl --? 0 Pipe kL - 0 + THTGT Beam - 0 + THTGT 0 c.o 0 'tj< ~ II Cl) > 0 Q) tj' ::E 0 -0 II 0.. l:::il ...--.. 0 p. - 01 ---0. : I ro u J ,,,.--.__ ? I ~ s~ .. ' ....__,.. . '' ' 0 _, _Q,l ) r, @ r , 0 ' 01 I '' I ?_-, -U) 0 tj' 0 0 0 0 0 0 0 o' 0 0 0 0 0 0 0 r-- c.o l[) tj' C"1 01 ......-4 s1unoJ Figure 6.2 : 0tgt- Spect rurn for Run with Beam Halo and Sli t Scattering 225 ~ cjq. Slit Slit = Scattering ~~::=ro-J Scattering "'1 Events Events ~ Negative Spectro-0) meter Angles ~ ? ---? to Dutt.lion o11ncru,r.re Dirtt.tion ol lncru,r. ?,l (") ';>;""' Aperture ~..., \ 0 t-.:) p t-.:) i:l cr, p_. p_. p (1) Counts Low High Low Counts .,.... Intensity Intensitiy Intensity 0 r:J'J I t Ii\ WI t,:,:."..: do r:J'J (") \& \ilR ?, ,l .,,....... -0+ THTGT Target Target - 0 + THTGT (1) ':!. i:l ~ 6.2 Line-shape Fitting Fitting of the replayed spectra was performed with the line-shape fitting code ALLFIT [Kel ALJ. Tl1e searcl1 code employs a Poisson (E:2) rather tlian a Gaussian (x2 ) goodness-of-fit criterion and thus avoids the under-fitting of low-statistics data, which is a problem with the standard Gaussian criterion [Kel 81, Hyn 81) . The spectrum is descibed by a model function which is constructed from a background and a sum of individual peaks N y(x) = B(x) + LY;(x) . (6 .1 ) i = l Each peak can be described as the convolution of an intrinsic line-shape 1( x) and a resolution function R( x) which empirically considers spectrometer aberrations, target thickness effects, kinematic broadening ( dependent on t . arget mass and scattering angle) and beam properties y;(x) = l;(x) @R;(x) . (6.2) Peaks, whose natural width is negligible are described by just the resolution functi on. The most often employed resolution function shape is an asymmetric hyper-Gaussian in the central region 3 with left (L) and right (R) exponential 3 The widths of the left and right central regions might differ and the exponent of the argument o f tl1 e G auss1?a n nee d no t be 2?, exponents less (greater) than 2 produce pointed (flat) tops). 227 tails I "/ ~ He IK .~1UL I = "/ I. R(x) (6 .3) ...!:..=J!_ He IK ,_,wn I I H and p are the height and the posi tion of the peak, >.L ,R the left and I right slopes of the exponential tails , and W? ,R = w(l =i= a) the left and right I widths; herein , w and a are the total width and the asymmetry of the peak , resp ectively. The exponent of the Gaussian is 1 , K-y = 0.5(ln 2t 1h, and the : I I ? I 1; I left and right match points , mL,R = K-yWL ,R( - ln !L,R) 1h, include the left and ,I I ii I right match fracti ons , fL and /R . Finally, ? represents the curvature of the ? I ? I right tail. The standard shape for the 9Be and 160 peaks which have intrinsic width is a Lorentzian with height H, position p, width f and threshold Xt H(:x - :x,)2r2 I( X) = ~(:x - :x,)2+(p- :x,)2]+(:x - :x ,)2r2 (6 .4 ) { X > Xt, appropriate when the resonance position is within a few widths of the reac- tion threshold (here all the positions are to be interpreted as Q-values ) . The threshold for all of the low-lying 9 Be peaks is at 1.665 MeV (9 Be - 8 Be + 11) . 7.162 MeV, corresponding to the decay 160 - 12 C + a, is appropriate for m os t of the 160 p eaks ; for the 02 state a thres hold of 12. 128 Me V, c rre- sponding to (1 6 0 - 15 N + p ), is assumed to apply. Excitation energy, width and threshold of each state in the fit are stored in a "levels" fil e which is read by ALLFIT. These data are taken from [Ajz8G/ 8, Dix 86] for 9 Be, from 228 1-.r E., r c.m. Decay t Comments n (MeV) (MeV) (MeV) 3/21 0 stable 1/2t 1.680 0.217 11 1.665 5/21 2.429 1/21 2.78 1.08 n 1.665 5/2t 3.049 0.282 n 1.665 3/2t 4.704 0.743 11 1.665 : I Lor 6.5 1.25 n 1.665 7/ 21 and 9 / 2i . Table 6.1: Energy Levels of 9 Be; data from [Ajz86 / 8, Dix 86] . . : . : [Ajz86/8] for 160; the data. for 4?Ca are from [End 78] . Tables 6.1- 6.4 a.re r, a summary ( comments to some of the states appearing in these tables are r : made in Section 6.6.1). ' :' 229 I > - ]Tr E,, r c.m. Decay t Comments n (MeV ) (MeV) (MeV) ot 0 stable ot 6.0494 31 6.12989 2+ 1 6.9171 11 7.11685 r1 8 .8719 1- 2 9.585 0.420 a 7.162 2+ 2 9.8445 4+ 10.356 0.026 a 7.162 1 01 10.957 3+ 1 11 .080 unresolved 4+ 2 11.0967 2+ 3 11 .520 0.069 a 7.162 Table 6.2: Energy Levels of 16 0 ; data from [Ajz86 / 8]. 230 - j1f n Ex rc.rn. Deen t Comments (MeV) (M eV) (MeV) ot 12 .049 1- 3 12.440 0.091 /)' 7.162 : I I r2 ?I I 12.530 I' o;- 12. 796 0.040 p 12 .128 . : " .? f ' 2- 3 12.969 I 1' I 13 .08 13 .08 0. 13 0 7.162 2+ and 1- r , II' 3- 11 4 13 .259 0.021 a 7.162 I ' 1+ 1 13 .664 0.06l1 Cl 7.162 I 43+ 13 .869 0.089 Cl 7.162 f r6 13.98 0.02 /)' 7.162 ot 14.032 0.185 Q 7.162 4- 1 14.302 5+ 1 14.399 - Table 6 .3 : En e rgy Le ve ls nf 16 0 :( c ,rnt.) data from [Ajz86 / 8] . 23 1 J'" o+ n 1 ot 31 2+ 2+ 1 51 ot 2 : 11 I Ex 0 3.3521 3. 7364 3.9041 4.4915 5.213 5.249 ., ' I ? I , I I J'n" 4+ 4- 2+ 1-1 1 3 1 6.028 32 4t , I I Ex 5.279 5.6143 5.6301 5.9033 6.028 6.2858 6.5084 , I 2- and 3+ .' '' pr 4+ r ' ' n 3 33 2 6.909 6.931 1-2 7.11 I I I Ex 6.5436 6.5833 6. 7509 6.909 6.931 6.951 7.11 2+ triplet 1- and 4- Table 6.4: Energy Levels of 4?Ca; all states have negligible intrinsic width ( data from [End 78]) . 232 Figure 6.4 shows a representative fitt ed spectrum for Be0 . The abrupt rise in the backgound is due to the aforementioned decay threshold for 9Be. Noticeable are the strong asymmetry of the 1/2i state, which is only 15 keV above the threshold , and the broad Lorentzian peak4 which is prominent in the continuum region. The 2t state (11.52 MeV) of 160 with I' = 69 keV is a good example of a strong state with non-negligible intrinsic width . A fit to this state with the resolution function alone would be too narrow and underestimate the true cros~ section . Small peaks or unresolved peaks in multiplets can be extracted by lock- ing their positions and shapes together or to those of a strong peak nearby. Examples are the at of 160 which was always locked to its strong neighbour, the 31 peak, and the doublet and triplet states in 4?Ca ( e.g. at, 2; , 4t or 41, 2t ). Figure 6.5 shows a representative spectrum for this target . The pedestals visible to the left and right of the strong 31, 2t and 51 states can - not be attributed to (x / 02 )- or (x / 03 )-type aberrations (which would be visible in an x 101 plot). We believe they are either due to correlations with the vertical coordinates (y, ::E Q) Ii, ::E + 0 ..._., 0 0 f2 C\1 ....-1 >--, II p.. till (iJ ~ Q) ,..--... ' ~ ea6 0.. ~ ClJ w '" ,._0..,.,. 0 ~ .. ,' ~1 .c..o.. -0~ .' ,,' !2 _, ~ .c ege - - (l) ~? ::% 0 0 C\1 ~l ->--- - II Q) 0.. ::g ~ C2 + ~t ,,--... ----- 0.. >, : I I - bl) I ,I l ,II ...0__.,., 't + z H ro +2 'Ij Q) 11 u LD ~ 0 ~ lVlZ ?J Ii' 11 I ~ 0 ?...-i ,.....) ~g ro ?,.-....) () ~ -tj< ?J !2 ~? !o .....--i 0 -tj-< (:) C\2 0 0 0 0 0 .....--i .....--i .....--i .....--i .....--i s1unoJ Fig ure 6 .5: Fitted 4?Ca Spectrum 236 6.3 Formulae For Cross Sections and A naly zing Pow- ers In the following we denote the differential cross sections for up- and down-beam ori entations as CTu(B) = (dCT/dO)u and CTd(0) = (dCT / dO)d - T he unpolarized cross section is , analogously, denoted by CT0 (0) = (dCT / d0) 0 . For each beam orientation the differential cross section is given as where CTu ,d(0) are the differenti al cross sections (in mb / sr) , Nu,d the peak sums of the state of interest , LT u,d the scintilla tor ( or computer) li ve times, E u ,d the chamber effici encies, dO the acceptance solid angle (in sr ), t the areal number thickness of the target (in nuclei/ mb ), and nu,d the tot al numbers of incident protons . The scintillator or computer live times can be calculated from the ratios of the scalers S1 ? S2 ? BUSY and S1 ? S2 for each beam orientation . The efficiencies for each orientation are defined as the ratio of events that make at least two consecutive hits in both chambers and satisfy an extended PID test (includes particle identification , good one-plane angles and the cut in 0tgt) and all the events that pass the extended PID (multiple hits and 0- or 1-hit events in either chamber are automati call y excluded by the anal yzer) . Finally, the "clutter" factor (1 + J,:~:/ti), applied to the fin al cross sec ti ons, accounts glo bally for those events whi ch fire a single M UX twice (multiple hits) and which are not processed by the analyzer. T he total number of incoming protons can be calculated from the ratio of the total charge and 237 the elementary charge (1 .602 x 10- 19 C). T he total charge is the product of the sum of the left and right integrators, the integrator full scale and a device ch aracteristic scale fact or n., ,d = Q.,,d/e = [(INT(L) + JNT(R)) x FS/ 1000] /e. (6.6) For a composite target with n components of atomic masses A; (in g) the areal number thickness of the relevant species ( i) is the number of scattering centers for the beam and is given with the above units for charge and acceptance as (6.7) where NA is Avogadro's number (6 .022 x 1023 1111 0 }- ), Ji the stoichometric fraction of species (i) , d the target areal density in g/ mb and 0t the target angle ( angle of the normal on the target with the beam axis) . The target orientation was chosen to be in t ransmission geometry and the target angle usually to be half of the scattering angle. In this geometry the path length for the projectile in the target is independent of the position of the scattering center . Losses in resolution due to straggling a.re thus minimized . However , the cross sections may reflect nonuniformities in target composition and thickness, since the position where the beam strikes the target depends on the scattering angle. The spin-up and spin -down cross sections are given with th e unpo- la rized cross section, u0 ( 0) , the beam polarizations Pu,d , and the analyzing power of the target Ay as - ? ---- N ? (,."..). I ? ? ? ... ,,-.. ?. .?. .. a.. ?? 0. .? ._0_., O' ? 0 ~ ?? '.e ---+ 0 I') i N II') I ~ II') 0 0 0 I 0 0 0 0 0 0 0 _; I n ... ? ? . ? ? IM N N ,,-.. ? --? I ~ a? ? 0. .... ? .__, -+- . ? 0 .... --+- O' ? ? '.e :::-. ?? -- N .., 0 i II') 0. .. . .. I .I 0 II') 0 0 0 0 0. . ~ _; 0 0 0 I n ---?--? .. --..... . . IN --- N ,-... .. 0 ,,-.. I 0. a ?. . ... --- .... ._0_., 0 - '.e O' N .., . 0 i I I I 0 II') ~ II') 0 0 0.. . 0 0 0 0 0 I (..1s/qw) UP/ DP 'v Figure 6.16: 160(p, p') at Ep 100 MeV: 0~ (12.796 MeV) , 23 (12 .969 MeV), and 13 .08 (13.08 MeV ). 262 ..... . -+- ? ? ? I.., C\I ,C...'.)_ ? ? 0.. ......- ..- - .. I 8 ? ? -.A...., . --....., ? 0 I ~ ? .... .., 0 0 i N I I 0... l() . 0 l() 0 0 0 0.. .. 0 0 0 0 .... I I (.rs / qw) UP/ DP ?v Figure 6.17: 160(p, p') at Ep = 100 MeV: 34 (13.259 MeV) . 263 ), . ... ? ? ?.? . ? I (') ? N ? -::-- ? ? 0. ? I . ? ? -0. ? ? - o:i ... ...... - O' ~? O> ? - -- 0 7 0 I() 0 0 0 I() 0 0 c.i c.i ~ c.i I -I (.1s/qur) UP/ .op AV Figure 6.27: 9 Be(p, p' ) at Er 200 MeV: Lor (6.5 MeV ) 273 C'l ? ? + ? ? . ? .. , ? , . ., , ,_ ?? N C') . ,.-._ ?? I 0. . ??? ?? ? 8 ? ..0_., ? ? ? .-._, ?? ? 0 ? . ~ i.. ? O' ? . ? ? ? + . ? ? ..... ? --- 0 N i I 0 I() 0 0 0.. .. 0.. .. 0 0 ci ci 'c?i ~ I C'l ...... ? - ??,,".' !, + ? +N ----?------- N , ,, 0 ,--. I?? ~ I .... 0.. , ,,,. --.::: -8 ,,, -..-.. - .. 0_., 1 ' ..- -- --- 0 ~ O' .,; ;', ....... ,, ?? ?- -- ',,'\ --- .., 0 N i I I ~ I() 0 0 0 0.. .. 0 0.. .. 0 ci ci 'c?i . I , ? . C'l ?? ? ?? ? ? ? , , .. ?? N .? +- , ? 0 ,.-._ ? . I . . . 0. ? ? . 8 ..0_., . . - ? 0 ? . -- ?? O' ~ I ? ? ? ? ? ? ? . ?? ? ? 0 .., i N I() I 0 I() 0 0 0 "0.'. .. 0 0 0 0.. .. 0 ci 0 ci I (.1s/ qru) UP/ .op /.v Figure 6.28: 16O(fi, p') at Ep 200 MeV : Oi, at (6 .0494 MeV ), and 3~ (6 .1299 MeV) . 274 .. ?. . ----- -.- ? -.. ----# ,_ I =-c-- (\J C\l ~ ?? ........ ~ ? 0. ---?- ? ? 0 -?--- I - ..a.. ? .___., ?... .. -...- 0 --.. O" ~ ...-..- --?- .. + ...... - . .... ..... N ., .. 0 i. .. I. . I I ~ 0 ~ 0 0 . 0.. . 0 "0' 0 "0' ... I (") . ... ? ? ---- . . If fl ll ? ?? ,-_ . .v- (\J ?? ........ ., ........ ? ? I .? ? 0. . ? ? ?? a ? ._0__., ? . ._._._. , -? 0 r? ? O" ~ ? . .... . ? ... -+- ....... ?. .. . ------- N ., 0 i I I 0 0 0 0 0 0 0 0 "0' 0 "0' I (") .,. . -- ...p-- ,, ? ?? . -#- ,~ +- (\J . --+- ........ , .C...\..l. . -- ? --q.... I ? 0.. ? ? a ? ? ._0__., ? ? -- ...... .? ? ? 0 ? O" ~ ? : . ? ? ? . ? ? ?- -+? --- 0 i N 0. .. I. .. "I' 0 U') ~ 0.. ~ . 0 0 0 0 "0' 0 0 I (Js / qw) UP/ DP 'v Figure 6.29: 160(p, p') at Ep 200 MeV: (6.9171 MeV), (7 .1169 MeV ), and 21 (8 .8719 MeV). 275 .. ... ? -- -- ? .....- ... , ?? -+- ~ N ?? .s.:-t.'. ~ I ...... -.?.. .... - . - ..... I ?= E ? .__, ? --- ..... - --?---------?..-.. --- --+--- ,_--_ 0 i N I "I' 0 0 0 0 0 0 '0? 0 0 '0? 0 I - C'l ...... .. -#c- -- --?- ., ... -#- +N C\l - -?- N ..-.. I "'"+ "o. -----+- .. 0.. ..~. -- ..E._._.. , -....-... ? - '--' --0 ......... .. '.? --...-.. .-..... O' -+- -?- - 0 i N I "I' ~ '? 0 0 0 0 0 0 0 '0? I C'l ....-. - N - --+- I..N... I -E O' 0 N I I "I' 0 0 0 0- 0 0 '0? 0 '0? I (.1s / qw) up / op 'v Figure 6.30: 160(p, p') at Ep 200 MeV: (9. 585 MeV ), (9 .8445 MeV ), and 4t? (10 .356 MeV) . 276 ,. . ? ...- ------ .. ? ? ----- ---- N - ,,....._ ,. ? ? ? +M ('J . .. ? -- .. ~. I 8 ,-._ - ? ? ? Q. ... ? r::r ? Q ? ....... ., -?- ? ? ? 0 ? . ? ? ? ? ~ ? ? -+- ' 0 I() 0 I() 0 0 I "I' 0 - 0 0 0 0 0 0 0 - I ... -- - - N I --8- ~ r::r 0 0 I() 0 "I' ..; 0-I 0 0 0- I - -,_ N 0 ,-._ I --8- r::r ... . --- -+--.- .. -- -+---+-- ? -? - .. 0 I() 0 I() 0 I 0 I 0 ci ci ci 0 I ~v (Js/ qw) UP/ DP o- MeV), Figure 6.31: 16O(ji,p') at Ep 200 MeV: 1 (10.957 (11.097 MeV ), and 2t (11 .520 MeV) . 277 N -+- I - ..8--- .._.., ... ? , ?? - -- -- ?? ti- ? ....... ? i-- ., 0 N IO 0 IO 0 i I I ~ 0 0 0 0 ~ 0 0 0 I (") ---+'--- ...... -_____ __~ ....... I- t"l N ,,-... ? ,,-... . ?o.. -- -- I . ~? s 0 -- - .._, .,. -..-... - -- - -- 0 -- - o' ~ -------- ., 0 i N I I 0 IO 0 IO 0 ~ 0 0 0 0 0 0 0 I (") - - --? .~ -- N . ..... ---+-- .- ~ ? - ....... I ... t ..8. --?- .. I-?--+- ??? .-. .- --?--? ... . -~ ? .. ~ --?? -- - - .__ ., 0 N I I 0 IO 0 IO 0 0 I 0 0 0 0 0 0 0 I (.1s / qw) up/ op !.v Figure 6.32: 160(p, p') at Ep 200 MeV : at (12 .049 MeV ), (12.440 MeV), and 22 (12 .530 MeV). 278 ... ... -----+--- .., ? ~ co -+-0 ---+-- N ,. r C.."..) ... ,....._ I ..? ... ? -- -?...- --? -?-0. ...... -? -?- - a .?.... 0.. '-' --- O' -+-.. 0 --.- ? --?----'.? ... --??? ------+- N .., 0 0 i I I 0 I() 0 I() 0 0 0 0 ,..; 0 ~ 0 0 I (") --?- ,, ' N ,....._ - __,;:_ I -a -+- ? . . ? ?? ---- O' --+-- ? -. . -+- +.. - ? ?.. . N .., 0 0 I I I I() 0 I() -0 0- 0- 0- c:i c:i 0 I l - -- -- IN ,0.- ... N 0. .. ._0_.., 0 -...... - -- I -a +- - - ~ -+- - I N .., 0 I I I 0 I() 0 I() 0 0 0 0- 0 0 0 I (.rs / qw) UP/ np ?v Figure 6.33: 16O(p,p') at Ep 200 MeV: 02 (12.796 MeV) , 23 (12 .969 MeV), and 13.08 (13.08 MeV) . 279 ' ? ? ? ? ---- N +M ?'? ,-,s.-t'_ --:=ta,: ~ I ? ? 0. .-.-..... -.- 8.. ..... '- ? ._0_., ...-. . . ~ -----0 ---- ~ -----+--...... --.-......--+- -... 0 .., 0 IO 0 IO N I 0 0 ... 0 i .I .. 00 .. . 0 I 0 0 l I ... ,___ N -- I ..8+- ... ----- ~.... -- __::::!::- -- ------ 0 0 IO 0 IO ..,; 0 0 0 I ......... -- N .....~ .. --- I -4.-=-~..... _.._. .~_ ..... ..8... ...... ? ? ~..-.. .. .-.. -- -- ---?-?--+-...... +?- - - ------- --?-...... ...... 0 .., IO 0 IO 0 .I 0 0. . ..,; 0 ci 0 I 0 I 0 0 ,v (.ts/ qm) op/ op Figure 6.34: i?o(JJ,p') at Ep ~ 200 MeV, 3_; (13.259 MeV) , (l3.664 MeV), and 4f (13 .869 MeV) . 280 - '--- N I - ..8... N .., 0 I I I IO 0 I/') 0 0 0 c:i c:i ~ c:i .... I I I ...... N .0... .... -+- 0.. ._0_.,. - - ..._ I 8-..-...-. 0 ---+- I--- ~ --- O' ---- 1--- - -- '' I ' 0 0 I IO 0 I/') 0 0 c:i c:i c:i I (") I ____, I IO N .N.... ... ----'--- I--- I 0.. 8 ._0_.,. - ...... 0 "' --------------- - O' I .., 0 N I I I 0 IO 0 I/') 0 0 0 0 0 c:i c:i .... I I (.rn / qw) op/ op ?v Figure 6 .35: 16O(ji, p') at Ep 200 MeV: 2i (13 .98 MeV), 01 (14 .032 MeV ), and 41 (14 .302 MeV) . 281 +- l() ,.-.._ .-......- --+-- -- N I ..a.. ---:_=,3~~~~~-------.i - 0 N I .I .. "I' -0 I() 0 I() 0- 0 0 0 0 0 0 I I (.1s/ qur) UP/ op l.v Figure 6.36: 16O(p,p') at Ep = 200 MeV: and st (14 .399 Me V) . 282 M ? ? ? ? , ?? ? ? ? ,_ ? ? . ? N ? C") ? ,--.. ? ? I ? 0. ? ? ? -p. - ?? ? -..8... ? ? (0 ? ? ? ? u C er 0 ?? ... ? ? ? .... ? . ?. ? ? ? ? ? .. ? 0 0 1/) 0 N 1/) i I ~ ..; 0 0.. . 0.. . ci ci ci 0 0 I M ..... ... - ? ---- - ,,11? 'I, ,~ ... -?- +N -?--- - N ~ ,., ? 0 ,--.. .. . ? ,--.. I?? I ?" ---... 0. -p. -..8... -- --+- (0 u er --?-....-.-. ... ~ -- --....... -?--?----- .. 0 1/) 0 1/) 0 N i "I' _; I .0. . 0.I . . 0.. . 0.. . 0 0 ci ci I M .. . ? lo ? ? ? ? .? ? ? . +- ? N ? ,--.. ,0-- .. . ? .. . ? I ? 0. - , ? p. ?? -..8... '? ? .? ? (0 , ?? u ?? ?? er ? 0. ? .. . ? . ? ? ? ? ? ? ? ? 0 .. 0 1/) 0 .. N 0 1/) i I ... 0 0.. . 0 ..; ci ci ci "0.'. . 0 0 0 I 0 f.v (.1s / qw) up/ .op 4 200 MeV: 07? , Of (3 .3521 MeV ), nnd 31 Figure 6.37: ?Ca(p, p') at Ep (3 .7364 MeV) . 283 - + M N ,-.. ,0,.. ..._ I 0.. 8 0.. --(U-- ----- u o' 0.. . -- .. 0 .., "' ll') 0 ll') 0 N I i I -I I ~ - 0 0- 00 0 - 0 0 0 I C') ? , ? ? , ? ? . ? ? . 1 - . ? N l{) ~ ? ? 0.. I ? .- ? ? ? ? 8 ? ,._0__.... -? ,-.___.. \ ?- (U - u 0.. . --... O" ? .. ? ? ... ? -?-- --~ --?--?---- 0 .., 0 ll') " ll') ~ i I' I 0 0 0 0- -0 0- 0- 0- ..; 0 0 I C') ? -- -+-, ? ... ?? --- +- .... N ? C\2 ,-.. ? 'c' ? I ? 0.. ... ? ?? ? ... s 0.. ,.___.. :? .__, --- -(0 -? ? u ..... -- o' 0? .. . .. - ?? ? -- .? ? ? ? ? --?- ? 0 ., .. ll') 0 N 0 ll') 0 i I I 0 0 0 - I 0 0 0- 0- 0 0 0 I (Js / qrn ) UP/ DP /4v (3 .9041 MeV) , 5~ Fig ure 6.38: 4?Ca(p, p') at Ep 200 MeV: (4.4915 MeV) , and ot (5 .213 MeV) . 284 -- N ...?.. ? - --- I ..8... ?. .. . -- '- --- ----..+ ------- 0 ,., .. l/'l 0 \() ~ N ci i I I "I' ~ 0 I ... 0.. . 0 0 I 0 0 0 C") ... .. -- .. .. . ? ? -- N +- ,-... ,q' .... . ,-... ---0. -- --- I ..8... . -+ ? ? A . ? --(-0- .... ........ -- ----er c..> ??. . 0 .. . ----- -- 0 .. ~ <') l/'l ~ 'I':! N i I I .I .. ... ~ ... 0 0 0 0 0 I 0 0 C") .. .... .. ? -- -- . .... -- +N - N ,-... C\l .. ? ,-... --? 0. -- I ..8... ? ? A - ?? --(-0- ? c..> - - ----er ? ? . 0. . ? ?? -....-. -- +- -+- - N .., .. 0 l/'l 0 i 'I':! ~ ... I I I ~ ci 0 0.. . 0 0 0 0 0 0.. . I (.1s/ qur) up/ .op /4v 4?Ca(p, p') at Ep 200 MeV: (5 .249 MeV) , 4?t Figure 6.39: (5.279 MeV), and 41 (5 .6143 MeV ). 285 ..... --- ...... - --- co .. ----- C\l 0 N . +.. ? 0 ----- "' -?- .., N .. 0 "' \() 0 \() i- I I I I ~ 0 0- 0 -0 0- 0 0 0 I ? ..... ? ..... -+- . ? ? ... ? ,_ -?--+- ' . ? ...... - N '( , ,,-... ... . ,,-... ,' . .. ?: p, I -?- --?- ..p._,, -- -+- ...8..._.. I ' ? -+- , a,j ? ... t' .? c..> ? 0 ...... ... . O' I I, ? "' ? ,, ? . -+-- -...-.. - --?- .. 0 i N "' \() 0 \() 0 I 0 I - I ~ 0 0 0 0- 0- 0 0 0 I ., -...... -+- J ', ~-- i +M .. C\l N ---+--- ,,-... ..... 0. I ? -?-+ .-.... .. p._,, ..8.. a,j .. ?. ... c..> 0 ? "' ~ ..._, O' ? - --?? - -----+- ...... --+-- 0 N \() 0 \() 0 0 0-I I 0 0 0 0 I (.1s / qw) UP/ op r.v Fig ure 6 .40 : 4?Ca(p, p' ) at Ep 200 MeV: (5 .6301 MeV ), 1~ (5 .9033 MeV) , and 6.028 (6 .028 MeV). 286 -- ---- N I -a -----+-- ==== -+- N I I 0 0 -----?---- ? - - f--?-.... ..? ,, .. --- -- N ? I-+- --- I ? ? -?- .. . . ..... . .... -- -?- -a ? . O' ? -?-... .. ----..._ ------+- .. .., 0 N .I. . I "' 0 ti') 0 ti') I I. .. .I ~ 0 0 0.. . 0 0. . 0 0 0 ' I I' M ? ? ? ? . ? ., . ? . ? . ? ? 'C"")' N .? ,....._ ? . 0.. ? ? I ? , ? ._p.., ? . ? , ... a ,, ? ? .-__., ccs ? u ? ? ., ? 0.. . .. O' ? ? ? ? ? ? ? .. ? ? .......? -- . .. ... 0 j' N I "I' ti') ti') 0 0 0. 0. . 0... ~ 0 0 0 0 0 I (.rs / qw) UP/ DP ?v Figure 6.41: 4?Ca(ji,p') at Er 200 MeV: 32 (6 .2858 MeV) , 41 (6.5084 MeV), and 4f (6 .5436 MeV). 287 ? -?-- ? ? -?- ------- ? ...... - -- N ?? -- ---+- I ?? ? . ? .. .... . 8 - + -----. ?? ? .? : -? '- ... ? .. ---- 0 I 0 0 -+- N ? i---------- .. I ? ? I ? ? -? -- ---------- - 8 ? --+- ?. -+--+-- ,,I ---+-:. ?.. . - ?. .... -f-+ ----- ,' 0 N .., U"l 0 U"l I I I 0 0 0 0 0 0 ~ ~ I ? ? ? -- ? ? .. ? . IM ? (;) ? N 0 ? ??. 0.. . + I + ? . 0.. ? ---- -- ..8.... ; ,' ? d 1': p / ?? ."' ? ? ,; 4 ? + 4 0 .... I V I "' --;;:~ I P.o -o "" ,-... ' (I) -J-) -..s /4 ... II n .. Ci]" s... C\I ~ 0 - I-() n C\I 0 N 0 " ~ 0 0' 0 0 0 0 0 0 I I I I I (/\aw) s,O ocf (A aw) s,O W,J ... 8 0 +4 4' 0 ..... f ", 0 +Cl ,'/ .. 0 ,. ._: .. ,!>. ?? .. ? 4 ,; .. o 4' 0 0 ''? .. o +4 ,;/, ? o O" uo ' ? .. 0 ? Q) a:~ ~- ../' ci,o ~ .__, 0 ~ - 0 C\l ::--... - s ~ II -- - C"l ..... "' -- ...... ------Ci] s... ' __, -- C\I : \ --- --- \ I 0 0 ll"l 0- l-l"l C"l Cll 0 0 ll"l ...; 0 0 0 0 0 0 0 I I I (/\aw) s,n 'ULJ (/\aw) s,O 1. The magnitude of the density dependence of the imaginary central compo- nent for our empirical interaction is comparable to the PH interaction , but is much less than that of the LR interaction and is of opposite sign . While at low densities the empirical interaction is very similar to the LR interaction , at high densities it is much larger . On th e other hand , compared to th e PH interaction , the empirical interaction is larger at small 111 omentu111 tran sfers and smaller at large momentum transfers . In Figures 7.20- 7.24 we compare calculations based 0 11 the empiri cal in - teractions EMP from the fits to 160 and 4?Ca to LDA and NRIA calcu lations 318 which are both based on the PH interaction . Distorted waves for the NRIA calculations were generated with the PH g-matrix. The EMP description of the data is superior for all the states and all the observables. In particular , we want t o point out the analyzing powers at small momentum transfers which are overes timated by both the LDA and the NRIA . For the 160 elastic cross sections we observe that although the first maximum is described well by the empirical interaction, for m omentum transfers above about 1.5 fm - 1 the cross section calculation appears to be shifted outward a little bit too much. For 4?Ca this shift does not occur until about 2.2 fm - 1 . Finally, in Figures 7.25 and 7.26 we show the optical potentials for elastic scattering at this energy. The EMP potentials are based on the interactions fitt ed to 16 0 and 4?Ca, repectively. The LDA and NRIA potentials are based on the PH g-matrix and PH t-matrix, resp ect ively. The EMP real central potentials are much m ore repulsive in the nuclear center than either the LDA or the NRIA potentials. For 4?Ca the EMP potential assumes a positive value of about +11 MeV . In comparison, the NRIA potential has a strength of about - 13 Me Vin the center , while the LDA potential almost vanishes . The EMP imaginary central potentials are less damped than the corresponding LDA p otentials. 319 Retf Imtf Re,Ls [I m,cf50 0 0 ] ,,, Data set S1 b1 S2 d2 S3 b3 tU) d4 a41 .. , f..'. 160 ... 1.07 144.7 1.02 -0.07 0.83 7.14 FL 0.0 -1.58 ,, ,,,, 40Ca 1.04 140.0 1.00 -0.01 0.78 5.25 FL ? 1 4 = 1.0fm - 16O + 4oca 1.07 142.2 1.00 -0.04 0.78 5.88 FL [a:-y,66] = [3320] ., PH-Theory0 [1.0] 80.5 [1.0] 0.04 [1.0] 1.03 PH ref. : [Kel 90b] .., LR-Theory0 [1.0] 61.2 [1.0] 0.27 [l.O] 1.90 FL Table 7.3: Empirical effective interactions for 318 MeV protons ([Kel 906], and J. J. Kelly, private communication) . We use the following exponents .2 [a,,Bo] and masses ?: [3310], ?1 = 2.0 fm - 1 (Retf0 ) ; [2210] (Imtf0 ) ; [3320], ,. ? = 6.0 fm - 1 3 (Rercf5 ). Units: Si and d; (1) , b1 (MeV fm 3), b3 and a41 (MeV f fm 5 ) . Square brackets indicate that the parameter or component is fixed . ,. 0 Values from Table 2.5 . ' 320 6 /+. g ,: : 0 / + d 0 +. :0 ,/:+C:l 0 J ... N ~Cf? !.:. ' I f'o ! / 8 I 04- ,' __, I :: - 1 ,l.!?o I /4 + o , .-? + 0 r ,' d ? 0 4 + o ,.I .. + 0 ,'/ d + 0 ,..?, .. ? : ~ ~ ': : ~ 0 ., If) 0 If) 0 ci ci ci ..; 0 I ,-----.-----,------r-- --,-----,,--- --, ("l ,,,...,. 0 +? N 0 + .,. .. '"'ii:: ,--.. .,. 0 +Cl ,.. ,., 0 + .." 'i:::. .. I ,? 0 + d "'\,::: 0 + 4 ' .. -:::;::: 8 . 0 0 + ?? ; ,-::-;. . __, 0 + 4 .. ~ - 0 + Cl ',-::,.;: 0 O + ? 4 ., .... ~ O' u_o0, 0 + 4 '~ 0 + ',~ ~_ , 0 + 4 ' 0 + ? '0- 00 ...... 44 ', ,~ ?o ~ ?... ..4 ',\ ..... 0 ? 0 0 0 0 0 0 If) 0 If) 0 If) 0 0 0 '?I 0 ~ '? 0 '? ("l N N N N I I ("l \,4+ 0 ... ... 0 ? + 0 0 . 0 , I ?.+. 0 4+I . 0 0 0 N t I .... 0 0 ,. I ?+ -o .. 0 I I <+ o 1 4+ 0 8 f .. / .. 0 .. 0 - ~ ~_ , / .. 0 ,,?? ?. ... O' u_o0, ,? ?-~ . ??/ ? ~ , ?'/ ,..1/ _,,,_ .:,,.- 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 co 0 0 N '~? 0 '? '? 0 I ~ '? N ""' ?o C\I 0 + ? + ? ,--.? ??"O" ' + ? 4+ 0 / I 0 0 + 0 ?? 0 0 + ? I . 0 ..8.. 0 +? 0 + 4 / 0 o+?c:I / : ': +o ,, , .. oe / ,_. .<..1 ~o!0,? O" ~f( ?O 4) 0 .' ,.s_,0 . -...,_ >- b ,;:,,. . ., ' 4> ..._, ... -... _. " .. _ ..~.... O?? "" - 0 II') 0 0 0 0 0 0 0 lO 0 I{') 0 II') 0 0 -, I{') 0 I{') "" (") (") C\I (\J I{') 0 I I C\I C\I I I 4+ o'. 0 .. 0 .. .. " ?? Q 0O+..<., 4+,o \ 0 0 .. ?i. 0 I , 0 +? ... 0 0 +4 0 ?? : ~10 0 +? N ? 0 + : t..?. 0 ? ., 0 / ~ I I ?O 8 ,, ++ ?O . . ' ' / . ....... , 0 0+ cl ' / o?:4, ? O" u.,8 0 + ll- '?, 0 ? ... ' .. ,, 0 + 0 --: "' cl) 0: ::s O:c-o ,___, OC'J ~ II ... w (\J 0 0 ~ 0- "' 0 II) 0- II) "' N - 0 - N C\i 0 0 0 _; 0 0 0 0 0 0 I I I I I (N~W) s,O ay (J\aw) s,O Ulf ., CD ..,, . "' . , ,,. . ~ ~- -.1' ---- (') ,.8_._.._. , s... ..::..~ .. (\J ...... :.: ?., .. .... ' I ' \ ' I ' 0 "' 0 1/) 0 1/) 0- 1-/) 00 1/) 0 I C\I I - ~ 0 II) 0 1/) C\I C\I (') I I I I I I I I "I' (J\aw) ::,fl ay (Aaw) ::,0 Ulf Figure 7.25: Optical potentials for elastic scattering of 318 MeV pro tons by 16 0 for the EMP (solid), LDA (dashes), and NRIA (short dashes) inter- actions . EMP based on FL t-matrix , LDA on PH g-ma.trix , and NRIA 0 11 PH t -matrix . 328 ...._ _ ---............................ _____ -..... -,, ;,' ,,,,,;"' .-, --:::-,""' .,,,,.,., .... .,,,,.,,"' /,-- 0 0 C\l ' 1 which leads to a reverse density dependence of the imaginary cent ral component of the interaction . This result confirms the corresponding findings a t 318 MeV . Finally, we want to mention that for the case of 16 0 we used a grid on the interaction parameters and found a second solution in the space of x~- The grid is shown in Appendix D. We find that if S1 is restri cted to the vicinity of 0.88 , a slightly better value of X~ is obtained with a larger value of b1 , and values for the other parameters which are similar to the first solution . For a m ore detailed discussion of this , we refer to the paper of Flanders et al. [Fla 90] . 331 Retg0 Imtg0 ReT:0L S [Im,; 5 ] Data set S1 b1 S2 d2 S3 b3 tU) d4 a41 160 1.26 121.1 0.84 -0.28 0.72 4.65 FL 0.0 -1.92 l6Qb 0.88 152.2 0.80 -0.30 0.73 5.14 FL ?4 = 1.0 rm - 1 40Ca 0.82 236 .1 0.93 -0.18 0. 71 6.95 FL [o-y/36] = [3320] 16Q+4oca 0 .87 199.5 0.88 -0.25 0.73 5.80 FL ref. : [Fla 90] Theory 0 [I.OJ 76 .0 [I.OJ 0.15 [I.OJ 1.34 FL Table 7.4: Empirical effective interactions for 500 Me V protons [Fla 90J . We use the following exponents [a,,B5J and masses ? : [3310], ? 1 = 2.0 fm - 1 (Retg0); [2210J (Imtg0); [3320], ?,3 = 6.0 fm - 1 (Re,;5 ) . Units: Si and di (1), b1 (MeV fm3), b3 and a 41 (MeV fm 6 ) . Square brackets indicate that the para.meter or component is fixed . 0 Values from Table 2.5; &Second solution. 332 I() 0 I() 0- 0 I() 0 I() 0 ci ci ci ci ci ci I I I -I r,,~_,.,--.-,..,..,,..,........,~~~...-,--~~~~~-- C'l ~~::~.,~ I ....s_..,. , N L....~~.........JL.....,..~-'-'~~~.......,_~-~~0 I I() 0 0 0 0 ~ 0 0 ci ~ 0 I -I ,-,...,.....~,--.-~~-~-~~~~-- C') ______: _-___- -+-....,,......,~- ,,,,. / -; - C\I ---- ' ..s... - O' 0 ~ .........._~ ~_._.~ ~~.........c~ - ~ --'-~~~_Jo 0 I 0 I() 0 I() 0 N 0 0 0 0 0 0 0 I -I Figure 7.27: Comparison of EMP(1 6O ) (solid) , LDA (dashes) , and NRlA (short dashes) elastic calculations for 16 0 and 4?Ca at 500 MeV. The -~ N .-8 __, 'C' 0. ._0_., ? 0 ?? '.? "" ? ? 0 I() 0 ~ I() i "I' 0 0 ci 0 -I I 0 0 0 0... 0- ...; -- ....... N I ? -8 .__, 0 I() 0 0 _; I() 7 0 0 0.. . ~ 0 I r.v (.rs/ qw) UP/ op Figure 7.36: Comparison of EMPs from fit to inelasti c data only (solid) , and from a combined fit to both elastic and inelastic data (dashes) Shown are the 4f, 2+ and o+ inelastic states of 16 0 at 200 Me V . The data. are from 3 3 tl 11? 5 work . ' 349 +-- N 0 --I 0.. s ...0__.., ..... 0 ~ - O' 0 0.. . I() 0 I() 0.. 0 0 0 . I I b . (') ? .. ? +-- N 0 -I 0.. s ...0__.., . ...._.._. , 0 - O' ~ .. 0 Q i 0 I() 0 I() 0 0 0 .0. . 0 0 0 0 I -I 'd.o / .o "v Figure 7.37: Comparison of EMPs from fit to inelasti c data onl y (solid) , and from a combined fit to both elastic and inelastic dat a. (dashes) . Shown are calculations for the ground state of 16 0 at 200 Me V. The data are from this work . 350 7.5 A Dependence of the Effective Interaction If the LDA prescription is to be considered sound, the empirical inter- action must satisfy the following three conditions . The first condition is that the effective interaction must be capable of describing all the relevant data for a given target at a given energy. We have demonstrated in the previous sections in accordance with other work [Kel 89b, Kel 90a Kel 90b Fla 90] ' ' ' J that we can indeed find interactions which describe all the states for partic- ular nuclei at particular energies. As a second and more stringent condition, the effective interaction should be independent of the target nucleus in which the reaction occurs. In Figures 7.38- 7.52 we show for each energy and for each target calculations based on the interactions fitt ed to 160 (solid) and to 4?Ca (dashes) . The interactions from the combined fit s produce scatter- ing results intermediate between the two single-target fits and are omitted to reduce clutter. We see in these figures that , although we extract numer- ically different values 1 for the interact ion parameters from the two targets , the differences in the description of data are minute , especially for 200 and 318 MeV. The minor differences at 100 MeV are probably related to our difficulty in extraction of a stable interaction for this energy. Our analysis extends the A independence of the effective interaction , previously shown for the case of 16 0 and 28Si at 180 MeV [Kel 90a], to energies between JOO and 318 MeV and to a larger range of A. 1 In general we found that lGO constrained the pmameters of the empirical interaction better than 4?Ca which is a la rger nucleus and is overall less transpa rent th a n oxyge n. 351 1/? ? ? 1- ? --...... N ,-, 0.. I 0.. ..8... '-" 0 ~ - O' r 0 i N I "I' 0 \() 0 \() 0 0 0 0 0 0 0 0 0 I -I (') ? N ,-, + I ,-, 8 > ~ - 0.. O' '-" 0 - ~ 0 0 i N I \() 0 \() 0- ~ ~ 0- 0 0- 0 0 0 I -I (') . . . . ? N ? ,-, I 8 0.. '-" - 0 ~ ..... O' 0 i N I ~ \() 0 \() 0 ~ 0 0 0 0 0 0 0 I -I (.is/ qm) UP/ DP ?v Figure 7.38: Compari son of EMP(1 6 O) (solid) and EMP( 4?Ca) (dashes ). We show calculations for the 31, 2t , and 11 inelastic states of 160 at 100 Me V . The data are from this work . 352 -.. N I ? 8 ? . ._....... . ? 1/ ,? ? ? --- 0 ., 0 II') 0 II') N I ~ j I .0.. . .... 0 0 0 I -I 0- 0... . (") ?.? N \ ? ? ... ? H .. .. .. I ..8... ? + r> ,C\2 !' ._.... -... ~ ? ._0,., ?.? ?? 0 ? ? ? ? ~ ? 0 II') 0 N II') 0 0 0 j .I0. . ... . 0 0 I 0 0- 0 0... . ? -- .-. ?? ? ? c;,- N . ,,, ? +~ I -d' ?? ?/ ,-... ~ / .. .._.8..... .. _A__, 0 l ? ~ ~ -+- -== 0 II') 0 ., 0 0 ... II') 0 N I ~ 0 I 0 j I 0.. . ... 0 0.. .. 0.. .. "v (.1s/qlll) up/ op 40 ~gure 7.39: Comparison of EMP(1'O) (solid) and EMP( Ca) (dashes) lO~ show calculations for the 4{, 2,i, and Oj? inelastic states of "O at Me V The data are from this work . 353 ? ---- . ? ? ? +- C\l C\1 ~ / 0.. I .a ._p.,, .-8 _., a:i u O' ~ - ,., 0 i N I I ~ I() 0 I() 0 0 0 0- 0 0 0 ~ 0 0 I -I M ? -- . 1/.? ? ? 1- C\l (;) ~ ~ ~ 0. I E: . a:i -8 _., u ... ?? - O' 0 ? ? i. ::,.. .. 0 - N 0 i- I 0 I() 0 I() - ~ 0 0 0 0 0 ...; 0 0 0 I -I M .... +N C\l 0 ~ ~ 0.. I ._p.,, -- .-8 _., ? (0 u O' ~ - ,., N .. 0 i I I 0- I() 0 I() 0 I 0- 0 ~ 0 - 0 0 0 I -I (.is / qw ) up/ .op ?v Figure 7 .40: Compari son of EMP(1 6 0) (solid) and EMP( 4?Ca) (dashes). We show calculations for the Oi , 31, and 2t inelasti c states of 4?Ca at 100 MeV . T he dat a are from thi s work. 354 . ? IM N C'? ,......_ .? ( ,......_ 0.. I 0. -a ___. ___. co 0 0.. . O" 0 0 i N I "I' ~ If) 0 If) ~ 0 0 0 0 0 0 0 I (") .... ? IN N ? I ,C....'?.._ ,......_ 0.. I _0__.. 8 _-__. co 0 O" ~ 0 i N I "I' ~ If) 0 If) 0 0 0 0.. . 0.. . ~ 0 ci 0 I (") . .. ? ., ,> ,_ ? ? N ,l..{...)._ ,......_ ? 0.. I _0__.. . a ___. co 0 ? - 0.. . : O" 0 N i I 0 If) 0 If) 0 0 ~ 0 0.. . 0 ci ci 0 I (.1s / qw) OP/ DP ?v Figure 7.41: Comparison of EMP(1 6 0) (solid) and EMP( 4?Ca) (dash es) . 4 We show calculations for the 5~, 32, and 3~ inelastic states of ?Ca at 100 MeV. The data are from this work . 355 I ..E --..- ?r ? ? ?? ? +--' I ? 0 E ? ) ? --0-- ...... . ---- ? /2 ._0_., ? 0 / ~ 0 I{) 0 0 I{) .. i 0.. . ci ci ..; ... ci I I 0 0 0.. . "0.'. . ?v Hn / D :gure 7 .42: Comparison of EMP("O) ( solid) and EMP('?Ca) (dashes). 16 d e show calculations for the ground st ates of 0 and '?Ca at I 00 MeV . The ata are from this work . 356 C\I I a ----- N 0 I I 0 0 0 C\I ? +- ,......._ ,C...\.1._ I 0. 0. ---- -a 0 ~ - ----O' 0 i N ., 0 I I 0 l/') 0 l/') 0 0 0- 0 0 0 - ci ci ci I -I C'1 . 1/ 1- C\I ,-.._ ,(.."...)_ I 0. ...., ? 0. ? a -0--- ~ - O' ~ ?? I, \ 0 i N 0 I 0 l/') 0 l/') ~ -0 0 0 0 ci 0 0 I -I (.1s / qm) OP/ DP 'v Fig u re 7 .43 : Comparison of EMP(1 6 0) (solid) and EMP( 4?Ca) (das hes) . 16 We show calculations for the 31, 2{ , and 11 inelasti c states of 0 at 200 MeV . T he data are from this work . 357 ? N +-"' 0 .r: I ? 0. ?? -0. --8 0 er ~ .., 0 N i I I ~ In 0 In 0 0 0.. . 0.. . 0 0.. . 0 0 0 ... I (") ? N -I +-C\"1 ' 8 0. - . ? -0. .... er ? 0 ? ? ? ~ 0 0 i N 0 In 0 In 0 I 0 0 0 0 ..; 0 0 0 ... I I (") ----+--- -- N ,, - -I 0. 8 ?? 0. ? -- - -0 er ~ .., 0 N i I I 0 In 0 In 0 0 0. . . 0 0 0 0 0 0 I (.rs / qw) UP/ DP ?v 4 Figure 7.44: Comparison of EMP(1 6 O) (solid) and EMP( ?Ca) (dashes) . 16 We show calculations for the 4t, 2j , and 0! inelast ic states of 0 at 200 Me V . The data are from this work . 358 C'l ? +-- N C\1 -0. I -~ crj -8 0 O' 0.., . 0 M .. 0 i N -I I I 0 If) 0 If) ~ -0 0 0- 0 0- 0 - 0 0 0 I -I C'l ,_ - N C'? -0. I 8 8 crj - 0 O' ~ 0 0 i N I ~ If) 0 If) "-0' 0- 0- ~ 0 0 0 0 0 I -I C'l ... .... ? +-N N 0 -+- -0.. I - 8 ~ crj - 0 - O' ~ N .., .. 0 I 0- If) 0 If) 0 0-I I 0 0 0 0 0 I -I (.ts / qw) UP/ op 'v 4 Figure 7.45: Comparison of EMP(1 6 O) (solid) and EMP( ?Ca) (d ashes). 4 We show calculations for the 0!, 3~, and 2t inelasti c states of ?Ca at 200 Me V . The data are from this work . 359 ? IM N ..--. .(."-'-). I 0.. - 8 P. aj - u O' ? ~ ? ? .. 0 <'I i N \() 0 \() 0 0 I I I ~ 0 0 0.. .. 0 0 0 0 0 I n ( ? ? IN N ("') ,-.. ,-.. I 0.. - -..8P. ... aj ..u, O' 0 ? ? ? .. 0 N <'I 0 i 0 \() 0 \() I I ~ 0 0.. .. 0 .0.. . ..; 0 0 0 I n ,_ N l{) ..--. ~ I 0.. - -8 P. aj O' 0..0 , ? --- 0 i N <'I I I ~ \() 0 \() 0 0 0 0.. .. 0 0 0 0 0 0 I (.1s / qw) UP/ DP ?v 4 Figure 7 .46: Comparison of EMP(16 0) (solid) and EMP( ?Ca) (dashes ). 4 We show calculat ions for t he 5~, 3~, and 33 inelastic states of ?Ca at 200 MeV . T he data are from t his work. 360 +- +-- 0 N ? 0 ,---, -~ I Q. ,_Q. .._Q_., ? _.. .. 8.... ? 3 fm - 1 , the authors do not expect their model to perform well for higher momentum transfers . Figures 7.59 and 7.60 show calculations for elastic scattering from 4?Ca for 100 , 200, and 318 Me V based on the empirical interactions EMP (solid) which were fitted to 4?Ca and the global Dirac op tical potential model DP (dashes) . Considering that both 100 and 318 MeV are interpolated energies , the excellent performance of the Dirac phenomenology is extremely remark- a ble a t all the energies and _for all the observables. The only exception is the cross section at 200 MeV, an energy for which 4?Ca data [Ste 85] were available and included the fit . In Figures 7.61- 7.63 we compare the empirical optical potentials which are based on interactions fitt ed to inelastic 4?Ca (solid) and 16 0 (dashes ) data with the global optical potenti al (short dashes ) for the three energies. The parameters for the empirical interactions are those from Tables 7.1, 7.2, and 7.3. Since the spin-orbit potentials are small , we want to concentrate on the central potentials . At 318 MeV, where our empirical description of the data is m ost similar to the DP prediction, also the potentials are m os t similar. The DP imaginary central potential is about 17- 20% less absorptive than the empirical potentials, and the DP real central potential does not dis- play the dip in the interior which is present for the empiri cal potentials . At 200 Me V where th e qu ality of the data descripti on by th e empiri ca l interac- ti on s is still comparable to the Dirac phenomenology, we find th at the (large) imaginary central potentials are almost identical, while the real central po- t entials display differences whose impact on the scattering data a.re diffi cult 369 to judge . T he surface depression of the DP potential is more pronounced than for our empirical potentials. T hese, however , have a depression deeper m the interior whi ch is absent fo r the DP potential. Since elastic scat tering m some fashi on samples an average of the whole nucleus , it is conceivable that on the average the different real central potentials have the same effect . Comparing our empiri cal potentials to the DP potential is most interesting for 100 Me V , the energy where our model does very poorly and the DP does very well . We noti ce that our real central potenti als are between about 11 and 22 % m ore attractive than the DP potenti al , but the main difference is undoubtedly to be found in the imaginary central potentials. The DP poten- tial is much m ore absorptive within a radius of about 4 fm than the empirical potentials. For r < 4 fm the absorptive potential for the empirical interaction is only - 3 to - 4 Me V , whereas the DP potential assumes a depth of about - 11 MeV at the nuclear center . However , as we recall from Section 7.4, a t 100 Me V the damping factor S2 - d2 for the interactions from inelastic fits is much smaller than the corresponding damping factor for interactions which include elastic scattering (Table 7. 7) . Potentials based on the interactions from the combined fit to elastic and inelastic data, or to elastic data alone, would be much m ore absorptive in the center . 370 +--0 0. ._0_., 0 ~ 0 0 lO 0- ~ lO 0 lO ~ lO ~- 0 0 0 0 0 0 I I I I 0 0 +-- N 0 -I 0. ._0_., .....s_.._., , a:S u ?? - c,' 0.. . 0 N i I ~ lO 0 lO ~ 0 0 0 0 0 0 0 0 I -I .. (") N - -I ~ s ._0_., ? . ._.._.., 0 - c,' ~ 0 i 0 lO 0 lO 0 N 0 0 0 0- 0 0 0 ci I -I '/J..o I .o ?v Figure 7.53: Comparison of calculations for elasti c scattering at 200 MeV based on the empirical interaction EMP(1 6 0) (solid) , IA2 (long dashes) , NP (dashes), and NRIA (short dashes) . Both EMP and NRIA are based on the PH t -matrix . The data for u and Ay are from this work , the data for Q are from [Ste 85] and P . Schwandt , private communication. 371 ~~~~(') --: --~ --...... ..................= -~::::? ..... O" ...._._~~..._,_~~~---1-.~~~_.__~~_.__,o 0 I() 0 I() 0 ..... ci ci ci I I +- N 0 ,-.. ,-.. 0.. I s .._0_.., ...._.._. , ..: .. ::?- .. . . ' ..... . .. ... .. -- \ ' \-._ '-----''----'----'----"---'---'"---' 0 0 l() 0 l() 0 l() 0 l() 0 l() 0 I - ... C\l C\l M M I ... l() 0 l() 0 l() ... C\l C\l M M I I I I I I I I I I I I Figure 7.55: Comparison of the EMP(1 6 O) (solid) , full IA2 (long dashes), NP (dashes) , and NRIA (short dashes) optical potentials for 200 MeV elasti c scattering by 160. Both EMP and NRIA a.re based on th e PH interaction. 373 ,----------.-----~---~ <:O ll) ,? ,. , ? ,. ( ( ; \ I ~?. ' N ) / '----~__,___,__ -_-1. :. .__..J..._...J...__:..,__ 0 0 C'J <:O lf) o:~V ._t_i., c..o... \ .. 0 C'? .. ~ II ?? ... N 0 0 l-() 0- l() 0 l() 0 l() M N 0 N C\i 0 0 0 - 0 0 0- 0 0- 0 I I I I I (Aaw) s,O ocf (Aaw) s,O W,J (l) I - ;:;E ...0_,..., .-8 .__, 0 ro 0 u N 0.. , 0 i N II') 0 II') 0 0 I ~ 0.. . 0 0 0 ci ci ci I -I ("') ... -- - ~ \ -.. - -?'' ?"' > N ,......_ (l) I ;:;E . .. 8... 0 , 0 o' ........ 0 i 0 II') 0 II') 0 0 0 0.. . 0 ci 0 ci I -I H.o / .o ?v Figure 7.59: Comparison of EMP( 4?Ca) (solid) and Dirac phenomenology DP (dashes) calculations for r:, / r:,R and Ay) ? The data for 100 and 200 MeV are from this work, the data for 318 MeV are from [Fel 90]. 377 J (") > ---------- 4---i l() ,..__ I{) 0.::; O. o ' ID -(-l:l- -C--') -U II \ s -? ~ n ,._.._... 0. ., -- -:. ....-. --- w s... 0-- /' C\I .,.:.: ' 0 0 C\I st' --- -<1) \',, .,O.oM; . :::s N 0 \ '. (HI 0 , , o-M 0 ------- \0. . 0 I N \\,o. ... . C\l ..8.... '. ',o ... '-,o .,. fJ - <,? .... O" ,o .. \ '-o ,... , ??p .... ,?~o+:.. \ 'o ..,. \ \ ?:. . \ ~ +? --- - V ~ N 0 0 ,......_ 'l? ~?-. 0 0 C\1 I C\1 8 \:,~ QM -- ..... ~,o"" '\.?.,0-?+4 ---- _;: .. 5 O' "'?, ~ ..+. .. ,' V ~ 0 '11' 0 W" ... 0 u 0 ~~ '(> \ +4 . -- +J \ '?-~: -::r: 'o- ', ..... ~ ?., + 0... 4 0 ', + .. ~ ' , + ~ ?,. + \ .. ?? ?? + + ~ + \ + + + . ~ I + . 0 0 0 0 0 0 0 0 0 t() t() 0... . t() 0 I() I N N I I Figure 7.65: Comparison of the EMP(1 6 O), PH , and LR interactions for the lm.tf component; kF = 0.6 fm - 1 (triangles, short dashes) , kF = 1.0 fm - 1 0 (crosses, dashes), and kF = 1.4 fm - 1 (diamonds, solid) . 386 ? + \,'4 ? 0 0 \ -+ 'I,:.. I Cl) :::E '' -~?o I > .. 0 Cl) I ::::;J -?- 0 ..? 0 + 0 0 N :' t.oo I ? + 0 C...D... 1- co I .. 0 ?+ 0 I .C__'),. , I -40 (-Tj ' I <>-+ 0 0 40 I I - o .._. 8._..,. ., :J:: / .. ? ~ ,'. . / -~ 0 0.. // , .. ' / * O: O" / ...... ;.. / . .. ,./'/? ,,, .. . , ,,,,,. .. .. ,,,,,,,. ..,:..-- , / .... :.:- . . ? , .. ;.--: ,.,Y. ,.,.-; ? 0 ('? 0 ',\ ? + ',\ ?+ 0 .. 0 ? +. 0 \ \ - 0 \\ ? + 0 - 0 ? +. 0 .. 0 ---- ',\ 0 ',\ ?? 0 > <+ 0 Cl) ',\ ?? 0 > Cl) \1 .. 0 .. o ?? 0 :::E ::::;J ',I .. 0 ',\ <>? 0 .. o N - 0 :1 .. 0 0 : -? O 0 .. 0 ?+ 0 0 ;,' - 0 :, .. 0 ----I .C__\,l .. 0 ., ?o C\l ?+ 0 40 8 ,:1 :J:: .. . , .. ., :1 4t 0 .._.._..,.. , 4t 0 ,1/ ,1/ ?t- 0 0.. ~ .,7 , ,/ _,? o O" j, . ? j, ~ 4""'-J.._-L--L--''---''----'---'---'---'--' 0 0 0 0 "0 0 0 0 0 0 0 0 N ...,. ' CO O N sto -----I . - > 8 tlO ? 0 N 1-, ? a:, I'- 0 0 0 0 0 (0 ++- + ? I I I I O0 -:-;->-- - I ... I ::::s I 11) I :::i; / >-. ,,. / 0 tlO 0 0 0 ff, N 1-, 0 0 ---- - \ \ ,,...._ .:_::_:s ? \ ('l _, Cl) l ' .? ~ ' >-. ' > 0 tlO 0 0 ? ff, 0 ' N 1-, ? (1J !R o:::S ..., o-N Q) >, etc: I tlO 1-. '.'..!. .i,l : 8 (1J Q) i:: etc: CxJ 0 0 0 ~ 0 0 ., -> (1J 0 :::s ~..., O'-' N .? >, tlO I :,: 1-. 0 UC,. (1J ~ ~ c .? CxJ .,., 0 0 I() 0 (") N N ~ 0 0 0 "" / / / / / I I \ I I ~_.____.__~_.__~~-'-~-L-_._......J 0 0 0 0 0 0 0 0 co O ( J = 0). For the ground state one recovers with 41r M.x=o = Z the nuclear charge. Finally, the transition radius is the rms radius for a specific excitation (A .6) The plane-wave approximation , Eq . (A .1) , does not account for the disto- ti on of the incoming and outgoing waves by th e Coulomb field of th e target nucleus. For the actual analysis of the data, the di stortions due to the spl1 er- ical component of the ground-st ate charge distribution are included in t he distort ed-wave Born approximation (DWBA) [But 86] . Ground state as well as transition charge densiti es are usually expressed 400 as a linear series of the form N pi(r) = L anfni(r) , (A .7) n = l where the radial basis functions fn1(r) in principle can be drawn from any convenient comple te se t. Most oft en used in the analysis of electron scattering data, however , are certain variations of the Fourier-Bessel expansion , e. g. (FBE) (A .8) These basis fun ctions are all defined t o vanish for r > R, the cutoff radius . An alternative expansion, used for the 160 11 state , is the Laguerre-Gaussian expansion (LGE) (A .9) where x = r / b and L~ ( z ) is a generalized Laguerre polynomial of the form La( z ) _ ~ (- )m f(a + n + 1) zm n - ~o f ( n - m + 1 )f( a + m + (A .10) 1) m! The expansion is complete for any value for the harmonic oscillator parameter b. For a thorough discussion of the properties and the application of the various available expansions we refer t o [Kel 88] . In the following we tabulate (Tables A .1 and A.2) and graphically dis- play (Figures A .1- A.3) th e ground stat e and transition charge densities used in our analysis . P oint -nucleon densities were obtained from th e charge densi- ti es by num erically unfolding the nucleon form factor f(q) = [1 + (q / A)2J-2, where A = 4 .33 fm - 1 . Source for th e ground state density of 160 is [Lah 82], for 4?Ca it is [Emr 83] . Source for the transition charge densities of 160 401 is [But 86). Reference for tl1e transition charge densities of the ot state of 4oc a is [Har 84), for all the otlier states [Mis 83). It sl10uld be pointed out th at the ele c t ron scattering analysis of tl1e 40 Ca data 1? s cons1? d ere d to be st1? 11 Preliminary (J ? J ? K elly, . . . ) private commumcat10n . 402 .. I - 4t 2t o+ 3 -J7r 1- n o+ 3- 2+ 1 1 1 1 8.0 8.0 R,b 8.0 1.8 8.0 -'----- 8.0 8.0 E FB E FB E FB exp E FB E FB E FBE LG ~ ~ 26.944 50.4 71 -8.974 619 .386 a 1 202 .38 99 .542 73 .808 119.461 -82 .744 136.488 69 .711 a2 447.93 303.073 158.471 -147 .279 75.343 95 .774 a3 335 .33 402.446 108.520 -57.730 7.200 -100.967 2.520 43 .729 a4 35.030 293.928 -0.544 -58. 751 21. 704 -55 .323 2.033 13.465 as -122.93 125.227 83 .182 1.693 3.114 -35.584 aa -103.29 32.413 -34.005 -9.535 -1.839 -1.504 13.435 a7 -34 .036 4.905 -5 .508 0.620 -4.283 -0. 713 1.143 0.582 aa -4.1627 -0.450 -0.254 1.488 0.376 ag -9.4435 -0.229 -0.181 0.107 -0.556 0.248 a10 -2.5771 0.210 0.021 -0.047 0.221 -0.952 all 2.3759 -0.125 -0 .023 -0 .092 3.769 0.021 a12 -1.0603 0.067 0.019 a13 0.41480 1.843 1.062 .0195 20 .5 lvl., ., -0 0.6367 14.20 2.791 16.48 4.48 3.98 I I- R-tr 2.737 4.049 I 4.026 st1an'adb li ? A ?. ' Expansion coefli ci en ts ( without uncertain ti es ) for ground st e . rans11t ion ell d ?t ? ?r I6Q [L l 82 But 86] . The coefficients n.re n un ? arge enSJ res o a, , . . . Ie?fmJ~! of 10- 4 fm - ' . R, b and R" are in units of fin ; MJJ " n? units of , see Eq. (A .S). 403 I 0.25461 1.5917 3.450 Table A.2: Expansion coeffi cients (without un certainties) for ground st,at e and transition charge densities of 4?Ca fE mr 83, Mis 83, Har 84}. Th e coef- fici ents are in units of 10 - 4 fm - 3 . R, band Rir a.re in units of fm ; llfJ.J is in units of e-fm J+k, see Eq. ( A .5 ). 404 r- +.-. 0 + .... ,,......_ 0 v 0 Q) (1) ...(_1_) , -ro- u <-C>o . 0., . (\j ,-, 0 0 -d' N a:) .... .".V ~ _ , -1 r (\ I i r I \ 1 4 10 ~ I \ i 3 0 -2 ,r-;3 0 0- ~ I V f I \ j 2 "' - 3 1 5 ::l .~...- X 0= .. "<.,:': 0 0 E-- n Cl.. :::-- ~: t "'ca( e, e?Jo; j "' _J l -1 ~ - C z ,; j OQ (n -2 :< 0,, ~ 0 0.. l I I 3 [ I s: ~ (n 1 : t (\ ~ A l ::, =~...-. (\ " ca(e,e?Js; 2 2 (n ........ en M ..6.. 7 o' ,; ..,. '-V-- 6 0 .._ , 0 0 0 5 -l 0 "' 0 ~ \ I 1 -1 0 4 -2 ~ - en 3 -3 I- \ I -I - 2 X 00 w ., 2 <:: -4 L \ I l -3 E 0::: E-- l -5 .., Cl.. Pl 0 -6 l V 40Ca(e ,e?)3i j 4-4 ~ V ?Ca(e,e?)33 00 ~ -1 -7 -5 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 r (fm ) r (fm ) r (fm ) ~ B Differential Recoil Diagrams Consider inelastic scattering in the laboratory frame as shown in Fig- ure B .1. Four-vector conservation requires that (B .1) Using Lorentz invariance one can eliminate the unknown momentum of the recoiling (excited) target nucleus by (B.2) where Mis the target nucleon mass and X the excitation energy. After some algebraic manipulations one obtains with the auxiliary quantity A = E1 + M ( the total energy of the system) ? (B .3) In this equation m, p1 and E1 are the mass, three-momentum and (total) energy of the incoming projectile, p3 and ? 3 the corresponding quantiti es of the scattered (i. e. outgoing) projectile, and 0 is the scattering angle in the laboratory frame . Expressing ? 3 in terms of m and p3 and introdu ci ng B = 2m 2 + E 1 M - M X - '~ , yields a quadratic equation for p3 (A 2 2 - Pi cos 0)p; + ( - 2Bp1 cos0)p3 + (A 2m 2 B 2- ) = 0. (13 .4) '--v----' a C The solution of this equation is - b+ b2 - 4ac p3 = (B .5) 2a 408 which yields the energy of the scattered projectile (B.6) If E 03 denotes the energy of any reference state and Eb3 the one of any other state ( e.g. a different excited state of the same nucleus or any excited state of any other nucleus) , we can calculate the differential recoil, defined as (B. 7) Figure B .2 shows the differential recoil (here expressed as Q value, Q = - ~) at 100 and 200 Me V, with the gound state of 160 as reference state, for the measured excited states of oxygen and beryllium . Since at some angles we also observed the lowest two states of carbon , they have been included as well. 409 s -~ w~ '-" wrt'i' II '-" "Q".. ,i< II + ~ ~ II s 5:: Figure B.1: Kinematics of an inelasti c binary reaction. 410 > I.{) ' I V I.{) :::E / / 0 I[) 0 I 0 / I[) C\] I , 'tj< ~ , , I I , , f ' , 0 'tj< I I I[) ,........_,_ ,,! C') tlJ) / ,1 ; ,,',,1,' 0 QJ ,' ,/ C") "d I , ,'1 ,' I.{) I I C\l .Q I I 0 j I I C\1 ? ' I I ' I.{) I ,' I ,: I ,, ,, , ., ' .0.. .. ., , I I[) , ' . 0 ?- ?(\]- '-.. h 0 0 C') -J > V I :::E !? 0 J I 0 ?1 0 ..... I < aJ aJ C') aJ co ?,.? 0 _I-,, s lO 'Sf' aJ ..... 6 co N ""1' N 'Sf' 'St' ..... C) +? V C) .._I_ ., ..__., .._I_ ., ..__., .__.. .__.. 0. < r:n 0 U..."...l. 0 c...o... 0 i::: N 0 I -~ II .I._I_l., Cl) Cl) f/l - 1-, I-. Cl) Cl! (\I Cl Cl ct IIl ct IIl i i 0 'St' I 0 0 0 C') N ..... 0 0... ... 0 0 0 0 C') U".l I I I N 'Sf' (w0) X F igure C .1: Design K600 medium dispersion focal plane from RAYTRACE calculations in the D-coordinate system of dipole 2. T he dott ed lines a.re th e front and rear window of t he front VDC, the dash ed line is th e focal plan e, and the solid line denotes the wire plan e. The rays represent trajectori es of specific 5 wit h respect to the central ray. 417 IO N 0 + 0 N 0 + 0 ~ 0 0 ..... + 3 0 + 1/) 0 0 + 0 0 ,._o / / / '? 0 ,-s-.._ / 0 ;;/ 0 l{) / I / 0 / N 'N0? I 0 0 l{) 0 0 0 0... .. 0 -0 0 0 ol "'1' (") (\} (\} (") "'1' I I I (wo) x Figure C.2: Effect of the K-coil on the fo cal plane from RAYTRACE calculations in the D-coordinate system of dipole 2; the numbers represent the strength of the K-coil field in the center as fr action of the correspondin g dipole 2 field . The K-coil both shift s and deforms the fo cal plane . 418 0 0 C\l ~ ~---~---?---~ - --~---~------0 0 \\ 0 0 ~ ~ - - -<>- - ----0-- --+.. ---~- -- ..,_ -- ---0 \\,? . ... 0 ~---~-----o----~---~--- ? ------0 0 ,? .. co \., \ ?. ---? - -- ~---~--,-..-. --0------0------0 \'? \'-,. ... ?--- ?-- - -4- - - -4,)- -- -<>-- - ~- -- -<, ' ... ,? \\ , ... 8 8 --0 <)--- a 8 e ,\ 0 0-- - - -~ - - --0- - - -~ - - --0- - - -0- - - --0 \'- 0 ,.. 'tj' ,?.... . o-- - - .. - - -0- - - -~ - - -0-- - - -0-- - - -0 0 0 C\l 0 0 0 0 0 0 0 0 0 I.[) 0 I.[) 0 I.[) 0 co ['- ['- c.o c.o I.[) I.[) Figure C.3: Effect of the K-coil on nuclear lines in x 10 f (fr nt) from RAYTRACE calculations. The dashed lines are without K-coil ; for the solid lines the K-coil strength is 5% of the dipole 2 strength . Th e di amond symbols represent the seven 0tgt angles defin ed by the multi slit from Chapte r 4. The K-coil shifts and tilts lines; the strength of the tilt varies with x 1 . 419 0 cD 0 l() 0 C') 0 C\l u S N 0 0... ... 0 C\l I 0 C') 0 l() 0 l() 0 I.{) I.{) 0 I.{) 0 I.{) 0 I.{) I C') C\l C\l ...... ...... 0 I ..... ..... C\l C\l C') C') I I I (ruo) X Figure C.4: Effect of the I-I -coil on the focal pla ne from RAY T RACE calculations in the D-coordinate sys tem of dipole 2; the numbers represent the strength of the I-I -coil field in the center as fr action of the corres ponding dipole 1 field . The main effect of the I-I -coil is a (slight) ro t a tion of the focal plane. 420 0 0 C\1 ,--i \ \ ~-- - ~--- ?--- -o-;-- --~- - -~- - -~ '..\ 0 0 ??.\ 0 ~ ??, \ <>- - - --?-- - --?- --~- -- .,. _ _ _ .., __ _ --0 ' . '?.\ 0 - - - - ~.-- - ?- -- ?- ---(> 0 \.\ co ~ _- ?, \ e ---., \\ - - - ? - - - ? - - - i '~ - - -<>- - - -(> - - - -(> '-. \ \\ ~'.'> ?- - - ?- - - -4- - - .: - - --?- - - --0- - - -(> \\ ?., \ \\ , , 0 tj< 4 5 .3(1.5) 0.750 -0. 3 08 ( 6) 1.27 5 ( 6 ) -1 . 81 ( 13 ) 10 7 . 54 n.,.. .. 0.980(36) 129.9(1 . 6) 0.900 -0 . 111 ( 12) 0.915(13 ) 5.02(25 ) 6 5.82 5.57 0 .982 I .;:.. 1.080(31 ) 148.6(1.8 ) 1.0 5 0 - 0.0 51(11) 0.817(13 ) 7 .6 5(24 ) 8 5.73 1.E-2 ( 10) tv 0 1.153(30 ) 156 . 3(2.1 ) 1. 200 0.037(10) 0.764(13) 10 . 26 ( 24 ) 9 7 . 32 I c.,, :::l - ---?- OQ 11.11 5 ( 26 ) 174.0 ( 1.7 ) 0.946( 7 ) -0. 3 00 0.74 5 (12) 5 . 80 ( 22 ) 5 8 . 43 :l . 1.108(27 ) 164.3(1.7 ) 0.983( 7) -0.200 0.770(12) I 6.77(22) 6 6.78 5.63 -0 .028 C. .L 1.081 ( 29 ) 151.6 ( 1 . 7 ) 1.016 ( 7) - 0.100 0 . 810 ( 13 ) I 7.24 (2 3 ) 8 5.79 4. E-2 ( 10) I 1.022(32! 134.1 ( 1.8) 1.032 ( 8) 0.000 0.882(13) I .... 6.84(24) 4 5.67 I a, I -1.297(23) 161.8(1.8) 1.103( 9) -0.090 ( 13 ) 0 0.600 10.43(22) 8 7.99 I 1.154(2 5 ) 153.6 ( 1.8 ) 1.056 ( 9) - 0 . 076(14) 0. 750 8.40 ( 24 ) 6 6.02 5.57 0.873 ,.-.._ o.982(28) 137.6 ( 1.7 ) 0.991 ( 9) - 0.054(14) 0.900 6.20(26) 8 5.63 l.E-2 ( 11 ) <:,.;) ...... 0 . 737(35 ) 111.7 ( 1.7 ) 0.887( 9) - 0. 021 ( 13) 1.050 - 3.73 (2 5 ) 10 6 . 58 00 - 1 1.111 ( 30 ) 147.6 ( 1.6 ) 1.002( 9) - 0.102(13) 0.867(13) 5.00 2 5.84 3: 1.088(30 ) 146.4(1.7) 1.011 ( 9 ) - 0 . 083 ( 13 ) I 0.849(13) 6.0 0 2 5 .68 5.63 7.04 (b 1.069(31) 146.3 ( 1.7) 1 . 021 ( 9) - 0. 069 ( 13) 0.835(13) I 7.00 5 5 .6 3 3 . E-3 ( 27) < 1.058 ( 31 ) 1 44 .5 (1.8) 1.034( 9) -0 . 054 ( 12 ) 0.813(13) 8.00 5 .___, 5 . 67 ------------------------ ------------- -------=-=---=-===-----==------~-------~--=======---I ==-=========----===-===------- ---- I sl bl s2 d2 s3 b3 it chi r chig/ std parg I 1-3 ==-===-----=-====-----------------------------=-=------- =====-===-------------------- - ~ -er II 1 . 000 190 . 3 (2.4) 1. 000 - 0.069 ( 9 ) 0.701 ( 15 ) 7.12 ( 24 ) 4 . 90 4 . 90 ------?- ---c'D 0.7 50 173.7 ( 3 . 1 ) 0.8 10(9 ) -0 . 274 ( 13 ) 0. 73 6 ( 1 4 ) 5.05 ( 25 ) 9 4. 50 0 . 900 1 58 .6 ( 3 . 1 ) 0.803 ( 9 ) -0 . 287 ( 13 ) 0.73 3 ( 14 ) 5. 16 ( 24 ) 9 4. 4 7 4 . 46 tj 0 . 85 6 I 1.050 141. 9(3.0) 0 . 794(9 ) - 0 . 302 (12 ) 0.73 1 ( 14 ) 5 . 21 ( 24) 9 4.58 4 . E- 4 ( 33) 1. 200 123.7 (2.9 ) 0.78 5 (9 ) - 0 . 317 ( 12 ) 0.7 30 ( 14 ) 5.20 ( 23 ) 9 4 . 84 ~ I- --- -------------------- ----- -- 0 . 860 ( 2 5 ) 180 . 0 0.8 48 ( 9 ) -0 . 193 ( 13 ) 0.713 (14 ) 5 . 74(23) 8 4.35 0 . 819 ( 2 5 ) 18 6 . 0 0.8 56(9 ) -0.178 ( 13 ) 0.711 ( 14 ) 5 . 77(23) 8 4 . 40 4 .3 4 173. 4 I .=... 0 . 77 5 ( 2 4) 19 2 . 0 0 . 864 ( 9 ) - 0.162 ( 13 ) 0.709 (1 4) 5.79 ( 24) 9 4 .4 6 2.E- 4 ( 3 . 1 ) ..., 0 . 731 ( 24 ) 198 .0 0 . 872 ( 9 ) - 0 . 146 ( 13 ) 0 . 707 ( 14 ) 5.81 ( 24 ) (1) 9 4 .5 6 - - --- -------------- I (:ll .... / 1.217 ( 37 ) 114.4 (4 .0 ) 0 . 75 0 - 0.350 ( 9 ) 0.729 (14) 4 . 97 (2 1 ) 1 0 5 .08 (l ,.,._ -? 1.1 5 7 ( 37 ) 1 56.9 ( 3 . 9 ) 0 . 900 -0 . 1 8 9 ( 9 ) 0.717 ( 14 ) 6. 33(23) 1 0 4 . 53 4 .5 9 0 . 88 0 I 0 1 . 203 ( 3 5 ) l 79 . 1 ( 3 . 7 ) 1 . 050 -0 . 018 ( 9 ) 0 .6 90 ( 15 ) 7 . 77 ( 2 4) 10 5. 47 1 .E-1 ( 11 ) ts., 0) = 1 . 239 ( 35 ) 200.5 ( 3. 6) 1. 20 0 0. 155 ( 9 ) 0 . 649 ( 16 ) 9 . 10 ( 25 ) 10 7 .4 1 ------?-()Q -?--?----- ~- / 1.176 ( 36 ) 123 . 9 (4 . 1 ) 0.768 ( 7 ) - 0. 350 0 . 73 4( 1 4) 5 . 02 ( 20 ) 1 0 4 .89 1 . 221 ( 36 ) 122 . 3 ( 4. 0) 0 . 793 ( 7 ) -0 . 300 0.727 ( 1 4) 0.. 5 . 29 ( 20 ) 9 4. 8 4 4 . 84 1.278 ( 35 ) 118.6 ( 3 . 9 ) 0 . 820 ( 7 ) - 0 .30 8 I -0.250 0 . 721 ( 14 ) 5. 56 ( 20 ) 7 4 . 9 3 l .E-3 ( 11 ) ;;; 1.348 ( 3 5 ) 113 . 0 ( 3 . 8 ) 0 . 848 ( 7 ) - 0. 20 0 0 .71 4( 14 ) 5.84 ( 20 ) 10 5 . 1 6 - 0 / 1.11 3 ( 36 ) 154 . 1 ( 3 . 5 ) 0. 862 ( 9 ) - 0 . 185 ( 12 ) 0.4 50 7 . 67 ( 14 ) 9 6. 21 --- 1.186 ( 36 ) 131.5 ( 3 . 9 ) 0 . 803 (9) - 0.2 82 ( 12 ) 0 .650 5 . 94 ( 17 ) 10 4. 8 7 4 . 87 1 . 218 ( 38 ) 111.7 (4. 2 ) 0. 762 ( 9 ) -0.358 ( 12 ) 0 . 850 4. 03 ( 19 ) 10 5 .2 5 l. E-1 0.( 17422CJl ) 1 0 1.13 7( 39 ) 10 7 . 9 (4. 5 ) 0 . 738 ( 9 ) - 0 .38 4( 12 ) 1. 050 1. 99 ( 20 ) - 1 0 6.75 0 ---?--------- - / 1.207 ( 37 ) 122.0 ( 3.8 ) 0. 783 (9) ~ - 0.3 21 (11 ) 0 . 734 ( 11 ) 5.10 1 0 4 . 86 1 . 20 4( 3 7) 128 .4 ( 3 . 7 ) 0. 80 1(9 ) -0 .2 80 ( 11 ) 0.6 95 ( 11 ) 6.0 0 (1) 10 4 . 77 4 . 77 6.07 I < 1 . 202 ( 36 ) 133 . 7 ( 3 . 7 ) 0 .821 ( 9 ) - 0 .2 40 ( 11 ) 0.6 56 (11 ) 6. 90 10 4. 8 4 6. E- 5 ( 19) 1.202 ( 36 ) 137 . 9 ( 3.7 ) 0 .8 4 3 (9) - 0.2 01 ( 11 ) 0 .617 ( 11 ) 7 . 80 '--' 9 5 .0 5 -- ------------? ---- ------------------- ----=-==--======-=====--=======================I E List of Runs The notation in the following list of runs is as follo ws: t he fir st of added runs is denoted by ?>", each subsequent run is denot ed by "+"; excluded states following a ""'" belong t o the previous line . An "*" denotes a run with encoder problem and the quoted angle is the co rrected angle . An ?!" denotes a run with a scaler problem; the necessary scale fact or f for the a ffect ed polarized cross section ( u for spin-up , d for spin-down) is given in the last column . March 1988 runs show an "all" in tbe column for excluded states since they were not used at all in the present work , and are just listed ,,. \ here for completeness . 1 '1 ' ~ 427 C. - oo ? H - --- --======================= ===========-=======-===--- ---- ------------ ----- ---- ---- ----- ;;; ~ 0.. ~ j Run Angle By Evts Tangle Tgt _ Ap Ifs ~u~ Polup Poldn Ener~y Exc_:uded States I (1) r::r --------- - - ------- --- --------- - ~ O"' :=: ;" 348 -16.00 el 145 -8.00 new Bl 20 187 0.748 0.748 100.70 160:lml i:o s~ 0 349 - 16.00 in 100 -8 . 00 new Bl 20 187 0.749 0.749 100.70 (b ~ trj ,....,._ O~Q o.. 358 -14.00 el 116 -7.00 new 82 20 187 0.757 0.761 100.70 ~ ~.,.... O"' 363 - 12.00 el 186 -7.00 new 82 20 187 0.757 0.761 100.70 O O '-< i:,, 364 -12.00 in 57 -7.00 new B2 20 187 0.757 0.761 100 . 70 l60:4pl H C. ~----- 397 -12.00 el 93 -6.00 new 82 6 S87 0.757 0.761 100 . 70 .......,(b v o, ,..._ ~ (1) 365! - 10.00 el 185 -5.00 new 82 6 187 0.757 0.761 100.70 fu=6216.195 0 "d - O 390 - 10.00 el 154 -5.00 new 82 6 S87 0.757 0.761 100.70 H ~ (1) "d ::: . =~ - C 404 14.00 el 87 7.00 new Al 20 S87 0.757 0.761 100.70 160:3ml,2pl 7-- 0 = C 00 00 408 16.00 el 72 8.00 new Bl 20 S87 0.757 0.761 100.70 160:lml C 00 C i:,, "d ::;-: O"'.,..,.. 137 18.00 el 283 9.00 old Al 60 E87 0.727 0.750 100.50 ,...--... ::: ~ tr1 138 18.00 in 245 9.00 old Al 60 E87 0.727 0.750 100.50 160:3ml ~ ~ ,.c ..,, 224 18.00 el 208 9.00 new Al 60 187 0. 736 0. 748 100 . 70 '---' C II > 228 18.00 el 11 9.00 new Al 20 187 0.736 0.748 100.70 0 ? ~ + 229 18.00 el 168 9.00 new Al 20 187 0.736 0.748 100.70 H ::: ~ ,_. 230 18.00 el 83 9.00 new Al 20 E87 0.736 0.748 100 . 70 00 t; "?- -~_ c C > 262 18 . 00 el 61 9.00 new Bl 60 187 0.733 0.753 100.70 O + 263 18.00 el 68 9.00 new Bl 60 187 0.734 0.753 100.70 00 'o1. . = ~ 0.. .:I_(1). > 5 22.00 el 93 11.00 old Al 20 E87 0.756 0.774 100.50 160:3ml,2ml ; O (1) + 6 22 . 00 el 215 11.00 old Al 20 E87 0.756 0.774 100.50 9Be:lpl,3pl ::f: ::: --.., 7 22.00 in 202 11.00 old Al 20 E87 0.756 0.774 100 . 50 9Be:Lor ::: S?,_ +~ Z 212! 22.00 el 111 11.00 new B2 60 E87 0 . 736 0 . 748 100.70 fd=l0380.102 ,........_ (1) o 220 22.00 el 75 11.00 new Al 60 E87 0.736 0 . 748 100.70 00 i;:,... ~ .,..,.. > 222 22.00 el 87 11.00 new Al 60 187 0.736 0.748 100.70 '---' ~ - ? ~ + 223 22 . 00 el 95 11.00 new Al 60 187 0.736 0.748 100 . 70 9Be:5pl -~? H (~1) -~ ? C 139 24.00 el 132 12.00 old Al 60 E87 0.727 0 . 750 100.50 ~-::: C ~ 140 24.00 in 174 12.00 old Al 60 E87 0.727 0.750 100.50 160:3ml;9Be:Lor ~ ~ - ~;. 18 26.00 el 183 13.00 o ld Al 60 E87 0.756 0.774 100.50 :. ==- Cl.. (1) 19 26.00 in 232 13.00 old Al 60 E87 0.756 0 . 774 100.50 160 : 3ml;9Be:Lor ::: 00 ::ri 160 26.00 el 104 13.00 new Al 60 E87 0 . 736 0.748 100.70 .,.... i:,, g- ~ 161 26 . 00 in 51 13.00 new Al 60 E87 0.736 0.748 100.70 160:2p2,2ml,Oml;9Be : 3pl :::--- r.n c-- c:-- (1) 8 (1) o 28 ! 30 . 00 el 85 15.00 old Al 6 E87 0.756 0.774 100.50 fu=69.313 p,? Cb 00 -. 30 ! 30.00 in 258 15.00 old Al 20 E87 0.756 0.774 100 . 50 160:3ml; fd=41.878 00 H Q' ~ 162 30.00 el 109 15.00 new Al 60 E87 0.736 0.748 100.70 ~1; O ~ 38 3 4 .00 el 127 17.00 old 82 20 E87 0.756 0.774 100 . 50 ?. 0 =::f: ? o.. > 39 34.00 in 22 17.00 old Al 60 E87 0.756 0.774 100.50 C 2:: =~ --+ ---48 ~ ()Q -0 ----3-4-.0--0 ---in 438 17.00 old Al 60 E87 0 . 756 0 .774 100.50 160:0p2 , 3ml --- ------------ -----------------------------------=----===------==== ::::, ,.J ;., ~ :::.~ o"pl H ... pl_o..lll (1) - 0 0.. O"' pj" ~ s~? g__ ;- ==-===============-==--====-===============-===============-------------------------------~ "Cl r; I Run Angle By Evts Tangle Tgt Ap Ifs Cup Polup Poldn Energy Excluded States I 8 >; (}q .:: t'.fj - - - - - - - ---- - ---0 := 155 34 . 00 el 228 17 . 00 new B2 60 E87 0.736 0.748 100.70 - g: pl oo >--' 156 34 . 00 in 178 17.00 n ew B2 60 E87 0.736 0.748 100.70 .:: (1) - ..... 3 S > 00 47 38.00 el 114 19.00 old Al 60 E87 0.756 0.774 100.50 ::: -? ~ 0.. O"' 48 38 . 00 in 376 19.00 old Al 60 E87 0 . 756 0 . 774 100 . 50 ,.... O"' ~ ____. 168 38 . 00 el 65 19.00 ne w Al 60 E87 0.736 0.748 100.70 9Be:3pl ::;-- (1) 0 tI:l (1) O,.... (1) 56 42.00 el 107 21.00 old Al 60 E87 0.750 0.766 100.50 9Be:lml ~ ..,. g__ Q 57 42.00 in 258 21.00 old Al 60 E87 0 . 749 0.765 100.50 pl~ 174 42.00 el 82 21.00 new B2 60 E87 0.736 0.748 100.70 - O"' r; (1) ,,... '< S 58 46.00 in 212 23.00 old Al 60 E87 0 . 748 0.764 100.50 ~ O ~ ~ 59 46.00 el 133 23.00 old Al 60 E87 0.748 0.763 100.50 9Be:lml ~:::. V ~ 179 46.00 el 99 23 . 00 new B2 20 E87 0.736 0.748 100.70 0 ~ :::: e-+- ..r.;.. _,-(o1) - r 80 50.00 el 77 25 . 00 old B2 200 E87 0.727 0.750 100.50 (1) 81 50.00 in 133 25.00 old B2 200 E87 0.727 0.750 100 . 50 160:3m4 ;9Be:3ml ,5p l _, ~ ~ 186 50 .0 0 el 100 25.00 new B2 60 E87 0.736 0.748 100.70 o < - II r; o? - 82 54 .00 in 204 27.00 old B2 200 E87 0.727 0.750 100.50 160:0ml;9Be:5pl "'" oo C ~ f-' 83 54 .00 el 83 27 . 00 old B2 200 E87 0.727 0.750 100 .50 ~ '2 . oo erg 190 54.00 el 125 17.00 new B2 60 E87 0.736 0.748 100.70 .... 00 ~ 5'] :;;.,o 91 58 .00 el 58 29 . 00 old B2 200 E87 0.727 0.750 100 . 50 160:2pl -c:, (1) c ~< 92 58 .00 el 55 29.00 old B3 200 E87 0.727 0.750 100.50 160:2pl;9Be:lpl ? ?., .,_ :(1::) 93 58.00 el 55 29.00 old A7 200 E87 0.727 0.750 100.50 160:2pl;9Be:lpl > 94 58.00 in 111 29.00 old B3 200 E87 0.727 0.750 100 . 50 160:0p2,2pl;9Be:3ml,5ml __,, ,,...- ,,... ,..-... + 95 58.00 in 103 29.00 old B3 200 E87 0.727 0.750 100.50 0 := C =8 194 58.00 el 100 19 .0 0 new B2 60 E87 0.736 0.748 100 . 70 9Be:lpl ,..., .... I-' 00 ?-:; - : 124 62.00 el 90 31.00 old A7 60 E87 0.727 0.750 100.50 "C=l ? - O"'____. 125 62.00 in 315 31.00 old A7 60 E87 0.727 0.750 100 . 50 9Be:3ml,lp l 0.. '< ~ 201 62.00 el 72 31.00 new A7 60 E87 0.736 0.748 100 .70 I (l) ~ ~ 0.. ~ + ~ 114 66.00 el 100 33.00 old A7 60 E87 0.727 0.750 100.50 160:0p2 ~ 0 ~ p, 116 66.00 el 140 33.00 old A7 60 E87 0.727 0.750 100 . 50 160:0p2 ..,. CD-? ;::. > 117 66.00 in 338 33 . 00 old A7 60 E87 0.727 0.750 100.50 - oo (1) O + 118 66.00 in 209 33.00 old A7 60 E87 0.727 0.750 100.50 --. p, -~ := 206 66.00 el 81 33.00 new A7 60 E87 0.736 0.748 100.70 160:0p2;9Be:5ml ~ ":':- =~ g__:::, 111 70.00 el 94 35 . 00 old A7 60 E8 7 0.727 0.750 100.50 00 (1) ~ 112 70.00 in 539 35.00 old A7 60 E87 0.7 27 0.750 100 . 50 oq ... o,. 209 70.00 el 70 35 . 00 new A7 60 E87 0.736 0.748 100.70 <. ::;; 00 ;::h - - - - - - '====== ------=----============ (l) - ? ~ -1 ~ C - ... ~ ~ ~ ~ ~ ~ {/, /1 I. :-::- 00. i-3 ('ti > 0.. ~ Run Angle By Evts Ta ngle Tgt Ap Ifs Cup Polup Poldn Energy Excluded States II l (e'n) o- ('ti g: =======================-==========--===========-=--=-=---- --=---==-===-==--=======-----------=------- :::i C'D 303 - 16.00 el 52 - 8.00 thn Bl 6 !87 0 . 740 0.744 100.70 p, ('ti 304 -16.00 el 56 -8.00 thn Bl 6 I87 0 . 740 0.744 100.70 ('ti -0 ~t_:!:j 305 -16.00 e l 12 -8 . 00 thn Bl 6 I87 0.740 0.744 100.70 ...... :::i ('ti ? o..t-,,) 306 - 16.00 el 59 - 8.00 thn Bl 20 I87 0.740 0.744 100.70 p., ()-q 307 - 16.00 el 49 - 8.00 thk Bl 6 I87 0 . 740 0.744 100.70 ~ .,..... 0- 308 - 16 . 0 0 e l 70 - 8.00 t h k Bl 6 I87 0.740 0.744 100.70 0 0 '-< ~ 344 -16.00 el 53 - 8 . 00 thk Bl 20 I87 0.744 0 . 741 100.70 H .,..... _.._p._l ~ ~ . 345! -16.00 in 18 -8.00 thk Bl 20 I87 0 . 744 0 . 742 100.70 fu=382.577 (I) V ,.. 346 - 1 6.00 i n 226 - 8.00 thk Bl 20 I87 0.74 5 0 . 744 10 0 .70 o''"O _,, 0 347 - 16.00 in 66 -8 .00 thn Bl 20 I87 0.747 0.747 100.70 '"1 H Q )2289 - 16 . 00 el 60 0.00 thk Al 2 588 0. 728 0.748 100.50 all "' (I) (I) p., \ +2290 -16.00 e l 86 0 . 00 thk Al 2 588 0 .7 28 0.748 100.50 all '"O < P., H s? o? & e 311 -14.00 el 38 - 7.00 thn Bl 6 I87 0.740 0. 7 44 100.70 ' C ~ ,.. 312 - 14.00 el 43 -7.00 thn Bl 6 !87 0 . 740 0 . 744 100.70 C en en 313 - 14.00 el 51 - 7 . 00 thn Bl 6 !87 0.740 0.744 100.70 '"O t=-:0-~ 314 -14.00 e l 41 -7.00 thn Bl 6 I 87 0.740 0.744 100 . 70 I' .-~-. . 1;:: en trj \ 315 - 14.00 el 56 - 7 . 00 thk Bl 6 !87 0.740 0.744 100.70 I? (I) (I) ..__, ? ,-Cl '"0 316 -14 . 00 el 50 -7.00 thk Bl 6 187 0.740 0.744 100.70 3 50 - 14 . 00 el 2 55 -7.00 thk Bl 20 187 0. 7 51 0.752 100.70 Op2 ~ ~; II ) 3 51 - 14 . 00 in 202 - 7 . 00 thk Bl 20 187 0.7 5 2 0.754 100.70 \ r\l en ~ ~ \ + 3 5 2 - 14.00 ,-.J in 136 - 7.00 thk Bl 20 187 0.7 5 3 0 . 756 100 . 70 '"O ::: 0 353 -14 . 00 in 102 - 7 . 00 thk Al 20 !87 0.754 0 . 757 100.70 ~ w - ? ? - "='"'1 0 - 14 . 00 in 49 -7 . 00 thn B2 20 187 0.7 56 0.759 100.70 0 ~ ~ ~ - 14 . 00 in 266 -7.00 thn B2 20 !87 0.757 0.761 I 100.70 0.. 0..,.. '\: n35~7 -14 . 00 in 182 - 7.00 thn B4 20 187 0.757 0.761 100.70 0 (I) 0- (2293 10.00 el 87 0.00 ~ thk Al ()q 2 S88 0 .728 0 . 748 100.50 all O"" ,; +2294 ~ 10.00 el 80 0 .00 thk Al 2 S88 0.728 0.748 100.50 all 0- '< = ~ ::::: 29 4 12 .00 el 43 6.00 thn Bl ::: tll 6 187 0.740 0.746 - 100.70 n 295 12.00 el 57 6.00 thn Bl :- V ~ 6 187 0 .7 40 0.746 100.70 296 12.00 el 54 6.00 0 thk Bl 6 187 0 .7 40 0 . 746 100 . 70 ,; (1) :: - 297 12.00 el 51 6 .00 thk Bl 6 !87 0.740 0.746 100.70 ........ -0 (1) M 299 12 .0 0 el 53 6.00 t h k Bl 6 187 0.740 0. 746 100 . 70 ,; Pl '"O 33 4 12.00 el 97 6.00 thk Bl 6 !87 0 .7 40 0 . 741 100.70 o' ~ g. II 33 5 12.00 in 152 6.00 ,.,. thk Bl 6 187 0.740 0.741 100.70 5ml,4pl -? 336 12.00 in 173 6.00 thk Bl 6 !87 0.740 0.741 ,; 100.70 5ml , 6 . 0 28 , 7 . 11 w Cl) =0 Cl) >-' >2297 12.00 el 76 0.00 thk Al 2 S88 0.728 0.748 100.50 i:: all 0 +2298 >-' -0 - 12.00 el 267 0.00 thk Al 2 S88 0.728 0.748 100.50 all === ? -r.n O"" 0 ..., ?Cl) >2 323 12 . 00 in 277 6.00 thk B2 20 S88 0.728 0.748 100.50 all ~ ::::: ] a;:: +2324 12.00 in 212 6.00 thk 82 20 S88 0 . 728 0.748 100.50 all -0 (1) i:: (1) 288 .,......._ . g < 14.00 el 32 7 .0 0 thn Bl 6 187 0 .7 40 0.747 100.70 289 14.00 el 32 7.00 thn Bl 6 !87 0.740 0.747 .:! 100.70 290 Op2 > - ----- 14.00 el 45 7.00 thn Bl 6 I87 0 .7 40 0.747 100.70 291 Op2 - ,; n 14 . 00 el 178 7.00 thn Bl 6 I87 0.740 0 ,; -' ~- 8 0.747 100.70 292 14.00 el 56 7.00 thk Bl 6 187 0 . 740 0.747 100 .70 ...., .c...-, - 293 14.00 el 53 7.00 thk Bl Cl) 6 187 0.740 0.746 100 .70 "8. --- r:r ,,:_, 337 14.00 el 102 7.00 thk Bl 20 187 0.740 0.740 100 . 70 '< z > 339 14.00 in 32 7.00 thk Bl 20 I87 0 .7 40 0 . 740 ::, 0.. +- + 340 100.70 14.00 in 154 7.00 thk Bl 20 I87 0.740 0.739 2301 100 . 70 g 14.00 el 79 lml,lm2 0.. - ~ 0.00 thk Al 2 S88 0.728 0.748 0 O :: ~ 2317 100 . 50 14.00 in all 420 7 . 00 .... thk 82 20 S88 0. 728 0 . 748 100.50 all ~ -? ~ (1) , D -~ ? 280 16.00 el ~- I ., 75 8.00 thn Bl 20 187 0.740 0.750 281 100.70 >< 16.00 el 56 8.00 thn Bl 6 187 0.740 0.749 282 100.70 ~~ Q... 16 . 00 el 58 8 . 00 thn Bl 6 187 0 . 740 0.749 100.70 ,; i:: - 283 16.00 el 67 8 . 00 thn Bl 6 I87 0.740 0.749 :=- 284 16.00 el 100.70 Cl) i:: 0.. 63 8.00 thk Bl 6 187 0.740 ::::: 0 .7 49 28 5 100.70 (1) (1) 16.00 el ()q 31 8.00 thn Bl 6 187 0.740 ~ 0.. :::n 0.748 286 100.70 16 . 00 el 46 8.00 thn Bl 6 187 0.740 0.748 ::;? Cl) ..., 287 16.00 el 100.70 39 8.00 thk Bl 6 I 87 0.740 ('O - 0 .7 48 100 . 70 ::, ;:.? ~ Ul ~ ~ 2304 16.00 el 79 0.00 thk Al 2 S88 0. 728 0.74 8 100.50 all ::, (1) 0 ' ' ' ' . -------------------------================------=================== "' CJ') ,...... :- :;- ((/'ll -. Ill H (n !:... 0 0.. ~ := 0.. c::r Run Angle By Evts Tangle Tgt Ap Ifs Cup Pol up Poldn Energy Excluded States I- ll .(.n., 0? . (n -0.. ~ 2311 16 . 00 in 216 0.00 ..., thk B2 20 588 0. 728 0.748 100.50 all ~ -.0.., ;:: 0 OQ c::: ('l ~ ;:: 132 18 . 00 el 123 9.00 thk Al 60 E87 0. 727 0 .7 50 100.50 0 er Ill t-' 136 18.00 in 357 9 .0 0 (/l thk Al 60 E87 0.727 0.750 100.50 ~~ 266 18.00 el 5 9.00 thn Bl 60 I87 0 . 740 0.757 100 . 70 s s (/l 267 18 . 00 el 26 9.00 thn Bl 60 I87 0 . 740 0 . 756 100.70 > ;:: 0.. ('l 268 18.00 el 26 9.00 thn Bl 60 I87 0.740 0 . 756 100.70 269 18.00 el 17 9.00 thk Bl 60 I87 0.740 0.756 100.70 :-:;-- er ;(:n: ----.,-. 270 18 . 00 el 52 9.00 thk Bl 60 I87 0.740 0.756 100.70 (n t'n O o 271 18.00 el 62 9.00 thk Bl 60 I87 0.740 0 . 756 100.70 (/l o Cb o 272 18.00 el 58 9.00 thk Bl 6 I87 0.740 0 . 753 100.70 ~ ~ 0.. Ill 273 18.00 el 35 9.00 thn Bl 6 I87 0.740 0.752 100.70 - -?e.r:.:.., 274 18.00 el 34 9 . 00 thn Bl 6 I87 0.740 0.752 100. 70 (n : 275 18 .0 0 el 20 9 . 00 thn Bl 6 I87 0.740 0.752 100.70 ~ 0 ~ p :: 276 18.00 el 34 9.00 thn Bl 20 I87 0. 740 0.751 100 . 70 (/l 277 18.00 el 29 9.00 thn Bl 20 I87 0.740 0.750 100.70 ~ ;:. V Ill 278 18 . 00 el 31 9.00 thk Bl 20 I87 0.740 0.750 100.70 .0.. , (n :: ,... 279 18.00 el 31 9.00 thk Bl 20 I87 0.740 0 . 750 100 .70 ..., (n M 341 18.00 el 79 9.00 thk Bl 20 I87 0.740 ......... -0 0.737 100 . 70 Ill -0 > 342 18.00 in 215 9.00 thk Bl 20 I87 0 . 740 0.737 100 . 70 -. (n -? n + 343 18.00 in 52 9.00 thk Bl 20 I87 0.740 0.736 II 100.70 0 144 24.00 in 224 12.00 thk Al 60 E87 0. 727 0. 750 100.50 6.. g + ~ + 145 24.00 in 546 12.00 thk Al 60 E87 0 . 727 0.750 100.50 0 O :: P 2244 24.00 el 70 11. 00 thk Al 60 E88 0 . 728 0.748 100.50 all ~ .,..... - ;::- 2247 24.00 in 9 34 11. 00 thk Al 60 EBB 0. 728 0.748 100.50 all - (n (n 0 2248 24.00 in - Cl)>< ~ 1209 11. 00 thk B4 60 EBB 0. 728 0. 748 100.50 all ~ P n 11 26.00 el 120 11. 00 t h k Al 20 E87 0.756 0.774 100.50 ----- ..., C .,..... 12 26.00 el 363 11. 00 thk Al 20 E87 0.7 56 0 . 77 4 100.50 C/l C 0... :::- + 13 26.00 el 589 11 . 00 thk Al 20 E87 0.756 0.774 100.50 oq t:: ~ (n 21 26.00 in 100 13. 00 thk Al 60 E87 0.7 56 0. 774 100.50 22 26.00 i n 103 13. 00 thk Al 60 E87 0.7 56 0.774 100.50 :;;? ~ C/l ~ (b :- -- ~ C/l 23 30.00 el ~ ~ ~ 259 15 . 00 thk Al 60 E87 0.756 0 .77 4 100.50 ;:: (") 0 p en ~ I ;. ~ o' ~ r-3 ------------------------------------- ----------------- - -====- - --------- ~ ~ ?= ~ ~ l===!~~===~~!===!;==!~~!=~!~~:==-~gt Ap Ifs _cup _Polup Poldn Ener gy Exclude~ State!_=====~-- ~ '""' ~- 0.. ~ + 24 30.00 el 320 15.00 thk Al 60 E87 0.756 0.774 100.50 .,..... 'O ~ >-i 27 30 . 00 in 251 15.00 thk Al 60 E87 0.756 0.774 100.50 n '""'o oq C t'.lj 32 30.00 in 204 15.00 thk B2 60 E87 0.756 0.774 100.50 0 0- ~ ? ~ ~ 00 - N 33 34.00 el 147 17.00 thk Al 20 E87 0.756 0.774 100 . 50 ~ ~ ?~ ~- > 36 34.00 in 262 17.00 thk B2 60 E87 0.7 56 0.774 100 . 50 E: ~ p_. p_. + 37 34.00 in 356 17.00 thk B2 60 E87 0.756 0 .77 4 100.50 (1) '-' ;. 0- ~ ~ > 41 38.00 el 92 19.00 thk Al 60 E87 0.7 56 0 . 774 100.50 (1) (1) 0 o + 42 38.00 el 95 19.00 thk Al 60 E87 0.7 56 0.774 100.50 oo O ~ Q 45 38 .00 in 246 19.00 thk B2 60 E87 0.756 0.774 100 . 50 n ::: 0.. ~ 46 38.00 in 198 19 . 00 thk B2 60 E87 0.7 56 0.774 100.50 e:_ oq 0- 1-1 49 38. 00 in 189 19. 00 thk B2 60 E87 0. 756 0. 774 100. 50 (1) .,..... '-< C --. 0 ::: 52 42.00 el 187 21 . 00 thk B2 60 E87 0.753 0.771 100.50 ~ 00 .,..._ ~ > 53 42.00 in 277 21.00 thk B2 60 E87 0 . 752 0.769 100.50 ~ ::;- V ~ + 54 42.00 in 205 21.00 thk B2 60 E87 0.7 52 0.769 100.50 4ml 0 (1) :: .,..... '""'"Cl -(1) trj 60 46.00 el 82 23.00 thk B2 60 E87 0.743 0.757 100.50 ........ >-i ~ ~ > 66 46.00 in 45 23.00 thk B3 60 E87 0.737 0.750 100 . 50 ,-, (1) n + 67 46.00 in 536 23.00 thk B3 60 E87 0.729 0.750 100.50 ~ :':: . ::;- II 68 46 .00 in 61 23.00 thk B2 60 E87 0.728 0 .750 100.50 ,.,._ 0 00 W 'rj C00 C S 72 50.00 el 119 25.00 thk B2 60 E87 0.727 0.750 100.50 W ~ - 0- O 73 50.00 in 27 25.00 thk B2 60 E87 0.727 0.750 100.50 7 t="'. ~ 74 50.00 in 57 25.00 thk B3 60 E87 0.727 0.750 100.50 C ::: ..C ~ > 75 50.00 in 155 25.00 thk B3 200 E87 0 . 727 0.750 100.50 .".C.--l .. ~ C (<1) + 76 50.00 in 5 25.00 thk B3 200 E87 0.727 0.750 100.50 ,~,- ,.-... + 77 50 .00 in 403 25 . 00 thk B3 200 E87 0.727 0.750 100.50 I=:! ? ._..,.::: 1-1 n 85 54 . 00 el 42 27.00 thk B2 200 E87 0 . 727 0 .750 100.50 0 C O > 89 54.00 in 218 27.00 thk B3 200 E87 0.727 0.750 100.50 >-i . ..:: :-:: ;::_ + 90 54. 00 in 301 27. 00 thk B3 200 E8 7 0. 727 0. 750 100. SO ~'-- ::: '< '.- ' > 96 58 . 00 el 19 29. 00 thk B3 200 ES 7 0 . 727 0. 750 100 . 50 o... 0.. +~ 'Z + 97 58.00 el 69 29 . 00 thk B3 200 E87 0.727 0.750 100.50 O~ :: 0 > 101 58.00 in 383 29.00 thk A7 200 E87 0.727 0.750 100.50 O ~ + 102 58.00 in 18 4 29.00 thk A7 200 E87 0 . 727 0.750 100.50 :;; ,,... - . - ::: (1) ,,... 127 62.00 el 99 31.00 thk A7 60 E87 0.727 0 .750 100.50 00 ...--.. ~ 8 > 128 62.00 in 53 31.00 thk A7 60 E87 0.727 0.750 100.50 R.. ~ Q.--' + 129 62.00 in 410 31.00 thk A7 60 E87 0.727 0.750 100 .50 '-' >-i C ~- C 0... :- 119 66.00 el 82 33.00 thk A7 60 E8 7 0.727 0 . 750 100.50 ::: (1) (1) > 122 66.00 1n 267 33.00 thk A7 60 E87 0.727 0. 750 100.50 ~< - ::s 0.. ::n + 123 66.00 in 203 33.00 thk A7 60 E87 0 . 727 0.750 100 . 50 00 ,.., g 2::: ;- ~ 103 70.00 el 75 35 . 00 thk A7 200 E87 0 . 727 0.750 100.50 - - e-- s.. - ----------------------------- . ------- ----------- -------------====--================= ~ ~ 11-11---11 II II II II II II II II II 11 II 11 11 II 11 11 II 11 II II II II II II II Ul II II Ql II 11.._. II II ,u II II .._. II II Vl II II II 'tl II Ql II 'tl II ..:.:.,. II u ""' >,. 0000 0, 1./Hl")l.f'ILl"I "(I) 0000 I C: 0000 II w .-t.-t..-4....-i II 11 C: 0000 II -o Lf'I i.n"' Ln II ,..... r- r- r- r- 11 0 IIP. 0000 II II I II a.11r-r-r-r- ll :, IJNNNN II ,..... II r- r- r- r- 11 o II ? ? ? ? 11<><110000 II II II II II a.ur-r-r-r- 11:, 11 coco coco II U II r.:ir.:ir.:ir.:i II 11 II II U1 1\0000 '+-I II o\0\0\0 H II N II II a, II r- r- r- r- .0: II<<<< I II II .? II .!(.!IC~.::..:: D'II J::.<:.<:.<: E-< II.._..._..._..._. II II 41110000 r-t l! OOOO D'II ???? C: tlt.nt.ntl"ILl"I !U IIMMMM E-< II II t11 I ?' i.n co r- .? r-\0~\0 > ..... ..... "' I >< <: <: <: <: '"' ?rf ?.-f ?.-f?..-4 Q) ..... 0000 0000 ~"' 0000 r- r- r- r- I II II II <: r- co?' o 11 ;l 000..-4 11 pc; .-t..-4..-4.-f II II I " ++ II II II II - --- 11 Table E.2: e) 4?Ca runs at Ep = 100 MeV (cont.) Notation: the fir st of added runs is denoted by ">", each subsequent run by "+"; excl uded states following a "" " belong to the previous line. An " i>' denotes a. run with a scaler problem; the scale factor J for spin-up ( u) or spin-down ( d) is given in the last column. 434 CJl =?> ::: cii" t-3 ===============================================================--===----------- ------ --- ----'E=. - ~- ~ I Ru n Angl e By Evt s Tangle Tgt Ap Ifs Cup Polup Poldn Energy Excluded States 0.. -~ ~ ,;;;r --------------- ------------------- -------- - - - - ==== ===========---------- -O"':;:: ;;" 867 - 6.00 in 546 0 . 00 new B2 6 I88 0.717 0.733 201.24 O - ~ 0t =~ 8 t_'.l:j 8 5 3 6.00 e l 118 6. 5 0 n e w Bl 20 I88 0 . 717 0 . 733 201.24 ?> ..., 0.. ? ,_, OQ W 840 7 .5 0 el 15 2 6. 5 0 new Bl 20 I88 0 . 7 50 0.766 201.2 4 ~ i:: .,.... O"' 846 7. 5 0 in 42 6. 5 0 new B2 20 I88 0.735 0.751 201.24 --......- :=:: O,... .. '-< - ?> 847 7.50 in 546 6.50 n ew B2 6 I88 0 . 733 0. . 749 20 1.24 cii" ~- ::;- V---;; 8 3 4 9.00 el 12 5 6.50 new Bl 20 I88 0.768 0.784 201.24 O-Q? :,,..-.. ~Cb '-I :: Cb 8 39! 9 . 00 i n 511 6 . 5 0 n ew B2 20 I88 0.75 5 0.771 201.24 160:2m2 ,2m3 ; fd=1003.315 ~ c., ~ Cb Q 821 10.50 el 108 6. 5 0 n e w Bl 20 I 88 0.770 0.786 20 1 .24 :=:: ? ;::. ~ ; 831 10. 5 0 in 3 1 6 6.5 0 new B2 20 I88 0 . 770 0 . 786 201.24 160:2m2,2m3 ::: ? ~ o ::;- :=:: 832 10.50 in 201 6. 5 0 n e w 8 2 20 I8 8 0.770 0.786 201.24 160:2m2,2m3 - ?> i:: C/l C/l .,.... cii" u, c ?> 767 12 . 00 el 308 5.00 n e w B2 20 I88 0. 766 0. 784 201.24 ::;- ,_, t::": O"',.... 9 15 12.00 in 60 0 .00 new B2 20 I88 0.765 0.788 201.24 ~'O ~ ~ M 916 12.00 in 489 0 . 00 n e w B2 20 I88 0.765 0 . 789 201.24 Cl ,_., . .0 "Cl i.n O c 773 13.50 el 233 6.50 new B2 20 I88 0.770 0.786 201.24 ,..... ?: ? Cb II 907 13.50 in 478 0.00 new B2 20 I88 0.764 0.785 201.24 9Be:Lor n('t) = =r:v 2... ~ *-- .,,_..,. . 0 780 15 . 00 el 279 6.50 n e w B2 20 I88 0.770 0 . 786 201.24 ,.,._ i:: .:-'. " 5 Ca; : 786 15.00 in 266 6.50 new B2 20 I88 0.770 0.786 201.24 ~ ;3 ,..... 787 15 . 00 el 138 6.50 n e w B2 20 I88 0 . 770 0.786 201.24 :=:: ::;- O.. C 788 15.00 el 224 6 . 50 n e w 82 20 I88 0.770 0 . 786 201.24 Cb Cb O"' + 789 15 . 00 el 91 6 . 50 new B2 20 I88 0.770 0.786 201.24 u,:::: '-< 790 15 . 00 in 181 6 . 50 new 82 20 I88 0.770 0.786 201.24 n :;?,. +::: z > 792 15.00 in 435 6 .50 new B2 20 I88 0.770 0.786 201.24 E.. Cb 0 + 793 15.00 in 300 6.50 new B2 20 I88 0.770 0.786 201.24 (t) r:n ~ ~ -, ?> -? ?> 801 16.50 in 97 6.50 new 8 2 20 I88 0.770 0.786 201.24 160 :2 pl ,lml,2p2, 2p3;9 Be : Cl =,_, Cb g,..... 802 16 . 50 in 359 6.50 new B2 20 I88 0.770 0.786 201.24 160:2pl,lml,2p3. ? 5m l ~ ~ 803 16 . 50 el 150 6.50 n e w B2 20 I88 0.770 0.786 201.24 !60:0pl,3ml,2pl,lml,2p3; 0 -' - 9Be: 3ml , 5ml ,..., ~ i:: ,..... 604 1 8 .00 el 72 9.00 new B2 60 E87 0.732 0.754 201.53 '--,.., ;:.: ~ ::,- 60 5 18. 00 in 20 3 9. 00 new B2 60 E87 0. 732 0 . 75 4 201. 53 ::,- Q... Cb 809 18.00 el 167 6.50 new B2 20 I88 0.770 0.786 201.24 9Be:3ml o' u, ::n 815 18. 00 el 23 6. 50 new 82 20 I88 0. 770 0 . 786 20 1. 24 9Be: 3ml ,_, n~ ,,... ,..., 816 18.00 in 152 6.50 n e w 82 20 I88 0 . 770 0. 786 201.24 u, ~ ~ 818 18 .00 in 4 97 6.50 new 82 20 I88 0 . 770 0 .786 201.24 'O O (l) 0 :: ? 0.. u, -, 597 19.50 el 92 9.75 new B2 60 E87 0 .732 0.754 201.53 ~ ~ 0 ?> 598 19.50 in 245 9.7 5 new B2 60 E87 0.732 0.754 201.53 i:: o- 0.. 6 10 19.50 el 66 9.75 new 82 60 E87 0.732 0.754 201.53 'O ~ ~ 819 19.50 el 100 6.50 new B2 20 I88 0.770 0.786 201.24 160:2ml ,Oml,2m3,4 p 3 ----- 0? : :~: ? 0....,. . ~ 590 21.00 el 106 10 . 50 new B2 60 E87 0 .732 0.754 201.53 __. ~ Qq C ------------------ ------ 0 ;j = ..., - ?> :fl >og~S.,H .... . n ?> Ill -- ~ 0 ~ b,. ~ \ Run Angle By Evts Tangle Tgt Ap If;--C~p Polup Poldn Energy Excluded States i:: 0.. "' 0.. ('D --- - - --- =======-=================--===-- "O ~ ...., ro 591 21.00 in 233 10.50 new B2 60 E87 0.732 0.754 201.53 ----."O ~ 0.. t:rj 613 21.00 el 103 10.50 new B2 60 E87 0 .732 0 . 754 201.53 .:: ..., 0 ..., ~ .___,, 0 ~ i:: 584 23.50 el 65 11.75 new B2 60 E87 0.732 0.754 201.53 0 c:;- ~-::: 585 23.50 in 550 11.75 new B2 60 E87 0.732 0.754 201.53 ..., Ca boq"..'.. . 617 23.50 el 51 11.75 new B2 60 E87 0.732 0.754 201.53 ~ O.. tJj 507 25.00 in 156 12 .50 new B2 60 E87 0.732 0.754 201.53 6.. ::: ~ ro ro O - ::: 0 577 26.50 el 104 13.25 new B2 60 E87 0.732 0.754 201.53 ~ . ..:: O'" ~ 578 26.50 in 230 13.25 new B2 60 E87 0.732 0.754 201.53 ::: ::< ro ro ..., n, 0 0.. e 627 27.25 el 130 13 .6 3 new B5 60 E87 0 .73 2 0 . 754 201.53 all ..-.. ~ ~ ,-J ._R__.,., 2 ...... 0- @ ~ t0 516 31.00 in 541 15.50 new B2 60 E87 0.732 0.754 201.53 ~ ,..... ~ ~- ::;- o 517 31.00 el 250 15.50 new B2 60 E87 0.732 0.754 201.53 ;:::_ pi O 0 Cb Cb i:: C 634! 33.25 el 124 16 .6 3 new B2 60 E87 0.732 0.754 201.53 fd=5182.256 _ ... :=-: II II II .._, II N II II"' II II II II.._, II '1J II II Vl II .... II II II II 111' II II II Cl> II.-< N I 111' II la C. I' I' ... N f .:-:I < I u II 0 0 >< 11 \.0 "' II ,.... "...'. II II :>, IIM M M M t,, 11'1 11'1 11'1 11'1 "Q) .... .... .... .... C: 0 0 0 Of "' N N N NII II C: ..,. ..,. .,. II ..,. II .'1..J. 11'1 11'1 11'1 "'II r-- r-- r-- r-- II 1 0 ? II II o. 0 0 0 o II II II II II II C. II N N N NII II ::1 1 M M M M II II.-< r-- r-- r-- r-- II II o ? II II o. 0 0 0 o II II II II II c. r-- r-- r-- ,... II II ::I ., ., ., a:, II 11 u II "' "' "' "'II II II II II u, 0 0 0 o 11 11-... II H "' "' "' "'II II II II II II II II II C. II in 11'1 11'1 11'1 II II < II Ill Ill Ill Ill II II II II II II 11.._, II :l ) ) ) II II 0>11 Cl> Q) Q) Cl> II II E-< II C: C: C: C: II II II II II 11 II 0 0 o 11 I'I .C-lt> If o0 I o, , "' "' ~ II II c: ..,. ..,. N r-- II II"' N N N NII II E-< II II ..,. II II" 11'1 M II .._', a, "' .0 ~ II II > "' ... ..,. II II"' II II II II II II :,, .... .... .... ,.... II II Ill I CO .. .. Cl> II II II II II II II II Cl> lllll 0 Ill o II If.-< II N 0 N o 11 II O>II ? II II~ II : a..,,. .... 11'1 II 11'1 11'1 If II II II II II II II II II 11 C: 11r-- r-- 0 II ::I II ..,. '? II "' "' "'II ""' " 11'1 11'1 If II II "' "' II II II II II II II 11 -11 II Table E.3: c) BeO runs at Ep = 200 MeV (cont .) Notation: the fi.r st of added runs is denoted by ">", each subsequent run by "+"; excluded states following a ?A>> belong to the previous line. An "*" denotes a run with encoder problem, an "!" a run with a scaler problem ; tl1 e scale factor J for spin-up ( u) or spin-down ( d) is given in the last column . 437 -a P> ::: en ? .....:i .... ::: > r-:l 7 - ~o..~ Run Angle By Evts Tangle Tgt Ap Ifs Cup Polup Poldn Energy Excluded States 0.. . ..:: cr- (1) C"' ==== 0 ~ (1) ::: ;- > 868 -7.50 el 38 0.00 thk Bl 6 I88 0. 717 0.733 201. 2 4 ~ ..... 0 + 869 -7.50 el 34 0.00 thk Bl 6 I88 0.717 0. 733 201.24 =<=; P., :0:::: : (-1) -L. .. J _____ .... o-qo..;i:,. 862 -6.00 in 427 6.50 thk 82 6 I88 0. 717 0.733 201.24 2m2 863 -6.00 in 708 0.00 thk 82 6 I88 0.717 0. 733 201.24 R. C ,,... 0- ,___, ::: 0 ? en . ~ c. ::: 841 7.50 el 42 6 . 50 thk Bl 20 I88 0.749 0.765 201. 24 Opl -?:.., 842 7.50 el 244 6 . 50 thk Bl 20 I88 0.747 0.763 201.24 ()-q ~Cb V ... 845 7.50 in 454 6.50 thk 82 20 I88 0.739 0.755 201. 24 <. ::i--'O -~ 0 > 848 7. 50 in 263 6.50 thk 82 6 I88 0 . 729 0.745 201.24 + 849 7 . 50 in 233 6.50 thk 82 6 I88 0.727 0.743 201.24 6 .91 gp,~<( 'l)Pl Pl 850 7. 50 in 500 6.50 thk 82 20 I88 0. 725 0. 741 201.24 6.91 >; s? ~ oc:: ? 8- :: 835 9.00 el 306 6.50 thk Bl 20 I88 0.767 0.783 201.24 Opl ?,l ~ ~i--cnC/l(/l 838 9.00 in 449 6.50 =-~ thk 82 20 I88 0.759 0.775 201.24 i---~ p., (1) ... . cr- - 822 10.50 el 94 6 . 50 thk Bl 20 I88 0 . 770 0.786 201.2 4 ..... 'O ~ ~ tr:1 828 10.50 in 327 6.50 thk Bl 20 I88 0.770 0.786 201 . 24 4ml ,lml,6.03 ,4 p2 ,6. 91 , ~ .... . ..c -0 829 10.50 in 189 6.50 thk 82 20 I88 0.770 0.786 201.24 ? 1m2,7.11 ,,... 0 C ~ ?'. ? (1) II 766 12.00 in 352 5.00 thk 82 20 I88 0.765 0.782 201.2 4 6.9 3 0u := ('t) ~ :::: - ::l ,,... tv >l'>- - -i-J? *= :: .... a 774 13.50 el 147 6.50 thk 82 20 I88 0 . 770 0 . 786 201. 24 c:,.,; ;3 .,.... 0 ~ 775 13. 50 in 62 6. so thk 82 20 I88 C 0 . 770 0 . 786 201. 24 00 ~ :=-o...~ ~ + 776 13.50 in 241 6.50 thk 82 20 I88 0 . 770 0. 786 201. 24 cr- + 777 13.50 in 202 6.50 thk 82 (1) (1) (1) 20 I88 0. 770 0 . 786 201.24 6 .91 , 7 . 11 en = '--< < 0 781 15.00 el 243 6 . 50 thk Bl 20 I88 0 . 770 ("l 0.786 201. 24 Pl .,.... + Z > 785 15.00 in 278 6 . 50 thk 82 20 I88 0. 770 0.786 201 . 24 ..... (1) - 0 + 794 15.00 in 334 6.50 thk 82 20 I88 0. 770 0 . 786 201 . 24 (1) "?'' >--) _ _-- ~ + 795 15.00 in 34 6 6.50 thk 82 20 I88 0. 770 0.786 201.24 lm 2 Pl ,; (1) ,,... ~ c:: >< --,. 797 16.50 in 537 6.50 thk 82 20 I88 0.770 0.786 201.24 o = n... .. 8 + 798 16.50 in 326 6. 50 thk 82 20 I88 0.770 .... 0.786 201.24 > 804 16.50 el 53 6 . 50 thk 82 20 I88 0. 770 ~ 0.786 201. 24 oC ..- + 805 16 . 50 el 78 6 . 50 thk 82 20 I88 0. 770 0.786 201.24 '--;., ~ ("O ==- o' ;:;-- 0.. (1) 603 18.00 el 71 9.00 thk 82 60 E87 0.732 0 . 754 201 . 53 .... =(1) "' ::ti 607 18.00 in 208 9 . 00 thk 82 60 E87 0.732 0.754 201. 53 c-+- f"""1 810 18.00 el 157 6.50 thk 82 20 I88 0.770 cnn?'cn 0 . 786 201. 2 4 'O O .,.... .,.... 811 18.00 in 675 6.50 thk 82 20 I88 0 . 770 0. 786 201.24 2p2 ,4 pl , 3m 2 ,3m 3 5? ~ 1012 18.00 el 69 9.00 thk 82 20 E88 0 . 743 0.. 0 0 . 763 201 . 40 ' (1) ...... C '""' Q' Pl 595 19.50 el 99 9.75 thk 82 60 E87 0.732 0. 754 201.53 'O'"d :::::0.. > 600 19.50 in 152 9 . 75 thk 87 60 E87 0.732 0 . 754 201. 53 .... 0 0.. + 601 19.50 in 404 9.75 thk 87 60 E87 0. 732 0.754 g.. 2.. 201 . 53 2p2 ,4pl ? - -~ ? 820 19.50 el 99 6.50 thk 82 20 I88 0 . 770 0.786 201.2 4 ----- 1007 19 . 50 el 83 9 . 75 thk 82 60 EBB 0. 74 4 0.76 4 (1) - .., 201. 40 o 3o--qC ..., -- ~ f;; ~.... . ;~:; ~ .0.. ... L...J ~ ~ =?o;;~C"' -------Run Angle By Evts Tangle Tgt Ap Ifs Cup Polup Poldn Energy Excluded States i;::O.. 'O (b ..c...n,oo..(.1.)- ...., 0 (b 589 21. 00 el 112 10.50 thk B2 60 E87 0.732 0.754 201. 53 ? '"Cl :::: 0.. t:fj 593 21. 00 in 540 10.50 thk B7 60 E87 0.732 0.754 201.53 6.93,7.11 ...., 0 ? 1004 21. 00 el 82 10.50 thk B2 60 E88 0 . 744 0.765 201.40 ...__.. 0 ::a: ...., ~ o lcor-----":::-::, ? e 583 23.50 el 101 11.75 thk B2 60 E87 0 . 732 0.754 201.53 1-1 ',-1 s(b, ..... CJl 587 23.50 in 566 11. 75 thk B2 60 E87 0.732 0.754 201.53 lm2 ~ V'< O"' CJl ...__.. ..... - ?' > 503 25.00 el 13 12.50 thk B2 20 E8 7 0.7 32 0.754 201.53 ::: .... + 504 25.00 el 70 12.50 thk B2 20 E87 0 . 732 0.754 201.53 ' ?' 0 0.. ::: > ~ 505 25.00 in 481 12.50 thk B2 20 E87 0.732 0.754 201.53 6.93 :::: :::, 0 Q 999 25.00 el 62 12.50 thk B2 60 EBB 0.745 0.766 201.40 ?' ::a: O"' 0 ::: - (b .,..... - (b ...., 574 26.50 el 69 13.25 thk B2 60 E87 0.732 0 . 754 201.53 ?' 0 0.. C > 580 26.50 in 213 13.25 thk B2 60 E87 0.732 = 0.754 201. 53 A... = + 581 26.50 in 301 13.25 thk B2 60 E87 0.732 0.754 201. 53 ...__.. ...., ()q O"' CJl ..... B ~ ~ .?,..'. . 946* 26.60 el 115 9 .00 thk B2 60 E88 0.760 0.783 201.24 CJl ,..., 0 ::: ()q ::a: ~ v_ M 512 28.00 el 60 14 . 00 thk B~ 60 E87 0 . 732 0 . 754 201.53 - 520 CJl 31.00 el 240 15.50 thk B2 60 E87 0.732 0.754 201 . 53 ::;- ::;- i:: C ~ + 521 31.00 el 567 15.50 thk B2 60 E87 0.732 0.754 201.53 lrn2 (b ' " CJl O"' '""' - l'--1 - C/l (<1') > 524 34 . 00 el 569 17.00 thk BS 60 E87 0.732 0 . 754 201.53 ~~ 8"d ;~::;? -(gb __ + 525 34.00 el 437 17.00 thk BS 60 E87 0.732 0 . 75 4 201.53 (l O"' (b ("l > 530 37 . 00 el 577 18.50 thk BS 60 E87 0.732 0.754 201.53 2..CO~~g + 531 37.00 el 480 18.50 thk BS 60 E87 0.732 0 . 754 201.53 C ::, ,..., .,.... s: ~2'-' 538 40.00 el 535 20.00 thk BS 60 E87 0.732 0 . 754 201.53 ~ *:::: 539 40 . 00 el 97 20.00 thk B2 60 E87 0.732 0 . 754 201.53 t:"+- :j 0.. O"' ~ > 967* 41 . 60 el 155 22.50 thk B4 60 EBB 0 . 757 0 . 780 201.24 (b CJl (b '< .,.... + 968* 41 . 60 el 112 22 . 50 thk B4 60 EBB 0 . 757 0 . 780 201.24 n ::= p., ?' 0 ::: .,.... > 54 4 43.00 el 548 21.50 thk BS 60 E87 0 . 732 0.754 201.53 ~ ~ + 0 + 548 43.00 el 551 21.50 thk BS 60 E87 0 . 732 0 .75 4 201.53 C/l :::: ::: ~ ~ - ? 972* 45.60 el 298 24.50 thk B4 6 0 EBB 0.757 0 .779 201.24 ~ i-1 ~ c-- 0 =C >< ;::;-' > 550 46. 00 in 562 23.00 thk BS 60 E87 0 . 732 0 . 75 4 201.53 ~ ~ (b + 551 46 .00 el 566 23.00 th k BS '--, :;; g_ 60 E87 0. 732 0. 75 4 201.53 - ? ::n ..., o..., ' .~..., ~ ~ 11 - 11 II II II II II II II II II II II II II II II II II II II II II t/l II II a, II II .? II II lt1 II II .? II II 1/l II II II II ,:, II II I a, II II 1J II II ::l 11 II ..-, II II U II II " II II ~ II II II II II II >, II MM MM MMM II O'l II U"I Lf'I "'II "'"' "'"'"'? II a, II .-4.-4 .......... .-4.-1.-4 II t:: 1100 00 ooo 11 t&J !I NN NN NNN II II c:: II II tn a.n ""''""'' U') U"'I ..n II ~ II II II II II II I >, II .-< .-< .......... ............... ai II a, a, ., ., ., ., ., II II muoo 00 000 ..-4 II OO 00 000 o, II !i! 1II " NN ! -.;t"<-.';f'' II "'"' ""''""''""'' II II c:: Ii"'"' 0\0 ::l llU'"\U'"\ P: II ,n ,n "'"' \ ""0""'r'"--' II "'"' "'"'"' II ,... + ,-, + ,-, ++ II - II Table E.4: c) 4?Ca. runs a.t Ep = 200 MeV (cont.) Notation: th e first of added runs 1s denoted by ">", ea.ch subsequent run by "+"; exclud ed states following a "" " belong to the previous lin e. An "*" denotes a. run with encoder problem, an "!" a run with a scaler problem ; th e scale factor J for spin-up (u) or spin-down (d) is given in the last column . 440 F Data Tables The notation for these tables is as follows: angles are listed in de- grees . Center-of-mass momentum transfers qc.m. are listed in units of fm - 1 . Center-of-mass differential cross sections a-c.m. ( q) are quoted in mb / sr and their uncertainties 6.a- in percent; the uncertainties in the analyzing pow- ers are absolute quantities . The tabulated uncertainties include statistical errors, fitting errors and uncertainties from the polarization . In the case of multiple measurements a weighted average is given, with the uncertainty being the larger of the uncertainty of the mean or the standard deviation about the mean . The uncertainty in the laboratory angle may be as large as 0.2? . The overall reproducibility of the data is estimated to be within 3% , the uncertainty in overall normalization is estimated to be about 5%. F.1 9Be(p,p') and 16 0(p,p') at Ep 100 MeV 441 ec.m. I- qc.m. I O"c.m .(q) I l'io-(%) I Ay I L\Ay I -15.80 17 .71 0.620 l.654E+02 0.5 0.260 0.007 -13 .80 15.47 0.542 2.181E+ 02 0.6 0.222 0.007 -11.80 13.24 0.464 2.756E+02 0.8 0.220 0.005 -9.80 10.99 0.386 3.170E+02 1.0 0.201 0.005 14.20 15 .92 0.558 l.963E+02 0.6 0.253 0.008 16.20 18.16 0.636 l.467E+02 0.7 0.261 0.009 18 .20 20 .39 0.713 9.974E+0l 1.3 0.296 0.005 22.20 24.85 0.867 4.314E+01 3.1 0.307 0.037 24 .20 27 .08 0.942 2.566E+01 0.5 0.383 0.007 26 .20 29 .30 1.019 l.555E+0l 3.2 0.414 0.010 30.20 33.73 1.169 5.214E+ 00 3.7 0.489 0.048 34.20 38 .14 1.316 2.185E+oo 2.3 0.476 0.019 38.20 42 .53 1.461 l.436E+oo 5.4 0.441 0.017 42.20 46 .91 1.604 1.056E+00 5.1 0.424 0.024 46.20 51.26 1.743 6.917E - 01 2.8 0.384 0.030 50.20 55.58 1.878 4.689E- 01 4.9 0.288 0.026 54.20 59.88 2.011 3.093E- 01 1.2 0.186 0.025 58.20 64 .15 2.139 l.935E- 01 0.6 0.018 0.010 62.20 68.39 2.264 l.180E- 01 2.8 -0.117 0.012 66 .20 72.59 2.385 7.587E - 02 2.5 -0.230 0.008 70.20 76.77 2.502 5.359E- 02 5.0 -0.273 0.028 Table F .1: a) 9 Be(f, p)3 / 2~; Er = 100 MeV 442 O"c.m.(q) I 60-(%) I Ay I 6Ay I 18 .20 20.41 0.711 4. 105E- 02 94 .2 0.765 1.159 22.20 24 .87 0.864 7.244E - 02 16.5 0.165 0.406 24.20 27 .10 0.939 l.030E - 01 12 .7 -0.087 0.190 26 .20 29 .32 1.015 1.129E- 01 6.7 0.243 0.137 30.20 33 .76 1. 164 9.965E - 02 15 .3 0.385 0.066 34.20 38.17 1.311 5.806E- 02 12.8 0.390 0.037 38.20 42 .57 1.456 3.175E- 02 20 .6 0.208 0.086 42 .20 46.95 1. 597 2.267E- 02 7.7 0.210 0.082 46 .20 51.30 1. 736 l.449E- 02 15.5 0.041 0.056 50.20 55 .62 1.871 l.045E - 02 12.4 0.085 0.076 54.20 59.92 2. 002 l.205E- 02 8.2 -0.188 0.046 58.20 64.19 2. 128 l.244E- 02 6.5 -0.099 0.095 62 .20 68 .44 2.255 l.093E- 02 10.9 0.009 0.868 66.20 72.65 2. 375 2.335E- 03 17.1 -0.174 0.11 9 70.20 76 .83 2.489 l.552E- 03 5.0 -0.216 0.072 Table F.1: b) 9Be(_p,p' )l / 2i (1.680 MeV) ; Ep = 100 MeV 443 0-c .m.(q) I Lio-(%) I Ay I LiA11 I -15 .80 17.73 0.617 4.119E+oo 3.2 0.101 0.042 -13 .80 15.49 0.540 3.479E+ oo 4.4 0.131 0.057 -11.80 13.25 0.463 2.409E+oo 3.9 0.048 0.051 -9.80 11 .01 0.385 1.658E+oo 4.8 0.196 0.068 14.20 15.94 0.555 3.596E+00 4.7 0.144 0.063 16.20 18 .18 0.633 4.837E+oo 3.9 0.076 0.051 18 .20 20.42 0.710 5.488E+00 4.1 0.189 0.032 22 .20 24 .88 0.862 6.361E+oo 8.4 0.199 0.038 24.20 27.11 0.937 5.961E+00 1.0 0.258 0.014 26 .20 29 .33 1.013 5.143E+ oo 6.1 0.289 0.007 30.20 33 .77 1.162 3.835E+oo 1.8 0.345 0.035 34.20 38 .19 1.309 2.334E+00 4.2 0.282 0.008 38 .20 42 .59 1.453 1.538E+oo 4.9 0.176 0.009 42.20 46.96 1.594 1.051E+oo 2.7 0.024 0.011 46.20 51.32 1.732 7.419E - 01 2.2 -0.104 0.023 50.20 55 .64 1.867 5.617E- 01 2.9 -0.188 0.010 54.20 59.94 1.999 4.123E - 01 1.9 -0.270 0.016 58 .20 64 .22 2.127 2.470E - 01 3.6 -0.325 0.040 62.20 68 .46 2.251 1.442E- 01 3.0 -0.390 0.017 66.20 72.67 2.368 7.922E - 02 1. 7 -0.435 0.017 70 .20 76.85 2.484 3.911E- 02 0.8 -0.488 0.010 Table F .1: c) 9 Be(p,p')5 / 21 (2 .429 MeV); Ep -= 100 MeV 444 24.20 27 .11 0.936 1.622E- 01 71.4 -1.358 1.658 26 .20 29.34 1.013 1.313E- 01 73 .3 0.371 0.931 30.20 33.78 1.161 1.158E- 01 39 .1 0.148 0.526 34.20 38.20 1.308 5.268E- 02 34.9 0.138 0.630 38.20 42 .59 1.450 4.729E- 02 62.7 0.545 0.864 42.20 46 .97 1.591 7.669E- 02 13.4 0.104 0.191 46 .20 51.32 1.729 5.917E- 02 17.4 0.280 0.256 50.20 55.65 1.866 5.749E- 02 38.9 0.183 0.202 58 .20 64.23 2. 123 2.082E - 02 15 .4 -0.561 0.217 70 .20 76 .86 2.482 8.412E- 03 7.0 -0.262 0.103 Table F.1 : d) 9 Be(p,p' )l / 21 (2.78 MeV) ; Ep = 100 MeV 445 18.20 20.42 0.709 1.732E- 01 25 .6 0.347 0.566 22 .20 . 24 .89 0.861 2.274E- 01 14.0 0.550 0.216 24.20 27.12 0.936 l. 545E- 01 22.8 0.659 0.334 26.20 29 .34 1.012 1.698E- 01 17.3 0.419 0.168 30.20 33.78 1. 161 1.131E-01 11.1 0.663 0.142 34.20 38.20 1.307 9.732E - 02 6.9 0.319 0.146 38.20 42.60 1.451 7.706E- 02 12.2 0.307 0.113 42 .20 46.98 1.592 4.813E- 02 19.1 0.467 0.073 46.20 51.33 1. 730 3.200E- 02 41.9 0.189 0.383 50.20 55 .66 1.865 1.540E- 02 20.3 -0.106 0.378 54 .20 59.96 1.996 2.031E- 02 17.4 -0.442 0.255 58. 20 64.24 2.121 6.535E - 03 15.3 0.189 0.236 62.20 68 .48 2.245 5.755E- 03 7.3 0.036 0.109 66 .20 72.69 2.364 5.300E-03 14.4 -0.095 0.213 70 .20 76 .87 2.480 1.357E- 03 59 .6 -0.263 0.810 Table F .1: e) 9 Be(p, p' )5 / 2t (3 .049 MeV); Ep = 100 MeV 446 O"c.m.(q) I ~u(%) I Ay I ~Ay I 18 .20 20.44 0.707 6.190E- 0l 22 .1 0.479 0.366 22 .20 24.91 0.859 2.982E- 0l 21.6 0.557 0.272 24.20 27.14 0.933 l.697E - 0l 44.2 -0.268 0.688 26 .20 29.37 1.008 l.358E- 01 33.6 -0.214 0.510 34.20 38 .23 1.302 l.059E- 01 15.8 0.631 0.200 42.20 47.02 1.584 3.006E - 02 23 .3 0.643 0.356 46 .20 51.38 1.721 8.871E- 03 54.7 -0.463 0.847 50.20 55.71 1.855 6.220E- 03 50.6 -0 .288 0.765 54.20 60.01 1.986 l.052E- 02 19.8 0.394 0.313 58.20 64.29 2.113 l.142E- 02 16.0 -0.292 0.229 70 .20 76.93 2.470 l.154E- 02 7.2 -0.391 0.103 Table F .1: f) 9 Be(p,p')3 / 2f (4 .704 MeV); Ep = 100 MeV 447 O'c.m.(q) I ~u( %) I A y I .6 A y I -15 .80 17.77 0.615 5.733E+00 35 .7 0.190 0.474 -11 .80 13.28 0.463 3.021E+ oo 16.9 0.120 0.222 18 .20 20.46 0.705 4.l0lE+oo 4.6 0.250 0.062 22 .20 24 .94 0.856 4.229E+oo 5.1 0.037 0.073 26.20 29 .40 1.006 3.S72E+oo 5.2 0.336 0.067 30.20 33.84 1.152 2.101E+ 00 2.8 0.305 0.036 34.20 38 .27 1.298 I.792E+ oo 12.1 0.274 0.023 38.20 42 .68 1.439 1.159E+ oo 2.8 0.187 0.040 42 .20 47.06 1.578 7.190E- 0l 4.2 0.171 0.060 46.20 51 .42 1.714 5.531E- 01 3.8 -0.068 0.056 50 .20 55 .76 1.848 4.810E- 01 5.2 -0.100 0.076 54 .20 60 .07 1.977 4.253E- 0l 4.8 -0.108 0.072 58 .20 64.34 2.103 3.179E- 01 3.8 -0.319 0.054 62 .20 68 .59 2.226 1.864E- 01 3.1 -0.299 0.045 66 .20 72 .81 2.344 1.853E- 01 11 .4 -0.457 0.165 70 .20 76 .99 2.458 1.037E- 01 10 . 7 -0. 799 0.083 Table F .1: g) 9 Be(p,p') Lor (6 .5 MeV) ; Ep = 100 MeV 448 0-c.m.(q) I ~a-( %) I Ay I ~ Ay I -15.80 16.88 0.621 3.369E+ 02 0.4 0. 251 0.005 -13.80 14.75 0.543 4. 672E+02 0.4 0.240 0.005 -11.80 12.61 0.465 5.914E+ 02 0.3 0.227 0.005 -9.80 10 .48 0.386 6.770E+ 02 0.3 0.219 0.01 4 14.20 15.1 7 0.558 4.156E+ 02 0.5 0.252 0.006 16 .20 17.31 0.636 2.847E+ 02 0.6 0.276 0.007 18.20 19.44 0.714 l.829E+ 02 1.0 0.293 0.002 22 .20 23 .70 0.869 6.185E+ Ol 1.1 0.332 0. 037 24 .20 25 .83 0.944 3.234E+ Ol 0.5 0.437 0.006 26 .20 27 .95 1.021 l.698E+ Ol 4.0 0.527 0.005 30.20 32.20 1.173 5.860E+oo 8.8 0.717 0.031 34 .20 36.43 1.322 4.595E+oo 2. 4 0.666 0.016 38 .20 40 .65 l.469 3.459E+ oo 1.3 0.673 0.012 42 .20 44 .86 1.614 2.212E+ oo 6.9 0.734 0.018 46 .20 49.06 1.756 1.041E+ oo 2.1 0.820 0.012 50.20 53 .25 1. 895 5.870E - 01 4.2 0.733 0.015 54.20 57.41 2.032 4.377E- 01 1.1 0.486 0.018 58.20 61.57 2.165 3.370E- 01 2.0 0.309 0.01 4 62.20 65 .70 2.294 2.363E- 01 1.9 0.187 0.018 66 .20 69 .82 2.421 1.402E- 01 3.0 0.117 0.016 70 .20 73 .92 2.543 6.473E - 02 4.4 0.023 0.011 Table F.2 : a. ) 16O(p,p)0?t; Ep = 100 MeV 449 O"c.m.(q) I ~o-( %) I Ay I ~ Ay I -15.80 16.91 0.616 1.275E- 01 10.2 0.309 0.134 -13.80 14.77 0.539 7.844E- 02 68 .1 -1.300 1.257 -11.80 12 .64 0.463 7.987E - 02 19.3 0.438 0.326 14.20 15.20 0.555 1. 744E- 01 43.5 0.018 0. 577 16.20 17.34 0.631 1.062E- 0l 66 .6 1. 296 1.074 18.20 19.48 0.707 1.346E- 01 13.3 0.179 0.203 22 .20 23 .74 0.858 1.657E- 01 11.6 0.242 0.160 24.20 25 .87 0.933 8.654E- 02 8.6 0.106 0.190 26 .20 28 .00 1.008 8.378E- 02 10 .1 0.212 0.136 30.20 32 .25 1.157 6.275E- 02 11 .9 0.163 0.093 34.20 36 .50 1.304 5.913E- 02 15.3 0.164 0.074 38.20 40 .73 1.448 3.909E- 02 13 .2 0.268 0.162 42.20 44 .94 1.591 3.819E- 02 15.3 0.393 0.092 46 .20 49 .15 1.730 2.370E- 02 15.8 0.600 0.142 54 .20 57 .51 2.001 1.478E- 02 22.0 0.191 0.094 58 .20 61.67 2.132 1.388E- 02 7.8 0.208 0.057 62 .20 65 .81 2.259 1.122E- 02 12.5 0.016 0.064 66 .20 69 .93 2.381 9.047E- 03 5.5 -0.013 0.081 Table F.2: b) 16O(p,p')0f (6 .0494 MeV) ; Ep = 100 MeV 450 Bc.rn. qc.rn. O"c.Tn.(q) I ~u(%) I Ay I ~ Ay I -15 .80 16.91 0.616 1.628E+oo 1.7 0.061 0.036 -13 .80 14.78 0.539 1.368E+00 8.2 0.019 0.107 -11 .80 12 .64 0.463 8.053E- 01 3.0 -0.090 0.035 -9.80 10.50 0.387 5.922E - 0l 9.6 -0.060 0.127 16 .20 17.34 0.631 l .763E+00 7.5 0.017 0.099 18.20 19.48 0.707 2.408E+ 00 4.6 0.083 0.028 22 .20 23 .74 0.858 3.492E+oo 1.0 0.129 0.033 24 .20 25 .88 0.932 4.077E+00 1.3 0.166 0.019 26 .20 28 .00 1.008 4.231E+oo 3.2 0.147 0.012 30.20 32.26 1.157 4.140E+00 0.6 0.210 0.031 34.20 36 .50 1.303 3.161E+00 3.3 0.168 0.007 38.20 40.73 1.448 2.455E+ 00 1. 7 0.097 0.005 42 .20 44.94 1.590 l.809E+00 2.8 -0.013 0.005 46 .20 49 .15 1. 730 l.323E+oo 2.4 -0.138 0.019 50 .20 53 .34 1.867 l.069E+oo 2.5 -0.255 0.019 54.20 57.51 2.001 7.913E- 0l 3.0 -0.347 0.008 58 .20 61.67 2.132 5.339E- 01 1.2 -0.421 0.004 62 .20 65.81 2.259 3.093E- 0l 2.3 -0.515 0.007 66.20 69 .93 2.383 l.662E- 0l 3.5 -0.651 0.013 70.20 74 .03 2.503 7.605E- 02 5.0 -0.785 0.009 Table F.2: c) 16O(p, p')31 (6.1299 MeV) ; Er = 100 MeV 451 -15 .80 16.92 0.615 2.462E+ 00 1.3 0.164 0.018 -13 .80 14.78 0.540 l. 986E+ oo 6.6 0.082 0.086 -11 .80 12.64 0.464 1.416E+oo 7.7 0.117 0.043 -9.80 10 .50 0.388 9.810E- 0l 7.9 0.055 0.092 16.20 17.35 0.631 2.450E+ oo 6.3 0.193 0.079 18 .20 19 .48 0.706 2.743E+oo 1.1 0.202 0.011 22 .20 23.75 0.857 2.510E+ oo 1.4 0.230 0.052 24 .20 25.88 0.931 2.022E+ oo 1. 7 0.295 0.019 26.20 28.01 1.007 l.581E+ oo 2.7 0.286 0.020 30.20 32.26 1.155 7.207E - 01 4.5 0.308 0.035 34.20 36 .51 1.301 3.414E- 0l 4.5 0.351 0.034 38.20 40 .74 1.446 1.803E- 0l 2.0 0.330 0.027 42 .20 44.95 1.587 1.285E- 0l 5.9 0.440 0.067 46 .20 49.16 1. 727 8.527E- 02 2. 2 0.630 0.031 50 .20 53 .35 1.863 5.318E- 02 7.7 0.810 0.049 54.20 57 .52 1.997 3.329E- 02 10.3 0.778 0.068 58 .20 61.68 2.1 27 2.723E- 02 19 .1 0.601 0.283 62 .20 65 .82 2.254 2.527E- 02 2. 4 0.150 0.045 66 .20 69 .94 2.378 2.418E- 02 1.5 -0.028 0.031 70 .20 74.05 2.498 1.937E- 02 2. 8 -0.155 0.01 5 Table F.2 : d) 160(p,p')2t (6.9171 MeV ); Ep = 100 MeV 452 Bc.m. qc.m.