Analysis of the exchange processes presented in the Supplement allows to understand the most important features of the mechanism of scattering. We provide examples when exact finite-range calculations following the nucleon-nucleus kinematics are clearly superior to the zero-range treatment of knoc-on exchange. Demonstration of the presented experiments and their study can make it possible to more reliably consolidate in memory the formalism set forth in Lecture Course II.
Thus, we have shown a significant impact of a number of polarization characteristics on the treatment of knock-out exchange amplitudes. This representation is based on the discrimination between different spin-dependent parts of effective NN interactions having differing nonlocal behaviors. It appears that the differences between amplitudes arise mostly from the nucleon-nucleus kinematics. Consequently, exact finite-range calculations using the program DWBA 91 follow the indicated kinematics quite satisfactorily in the description of the results at lower energies Ep. At the same time, a zero-range treatment of the knock-on exchange of LEA can be acceptable only at large Ep values, when the role of exchange processes is weakened.
So, it appears that a number of spin observables discussed here at energies Ep = 150–200 MeV are extremely sensitive to the nonlocal or exchange nature of interactions for the T = 0 state in 12C (Figs. 2, 4, 5, and Figs. b and c in Appendix 4).
At the same time, some other scattering characteristics show a relatively weak dependence on the method of accounting for nucleon-nucleus kinematics for exchange pieces of effective interactions .
This Supplement is devoted to the study of observables in inelastic scattering and the density dependence of the effective interaction used in this analysis. Thus, special combinations of observables for inelastic scattering are presented. To describe them the DWBA program is used that exactly treats knock-on exchange terms. It requires the application of a finite-range code for the exchange part of inelastic proton scattering. At the same time, for other polarization observables, a situation at which exchange is handled in a zero-range approximation is also permissible.
In this Supplement, we have focused mainly on such treatments that could be modified to follow nucleon-nucleus kinematics. For these purposes, we used suitable computer programs that incorporated a number of desirable features, namely it was a zero-range approximation of knock-on exchange in a DWIA code LEA from J. Kelly. Then we coordinated our experimental data with the exact finite-range calculations made using the program DWBA 91 from J. Raynal. In all these cases, we were able to compare the zero-range exchange amplitudes calculated using the LEA model with the exact finite-range amplitudes from DWBA 91. This made it possible to clearly demonstrate the results of such comparisons. Nonlocality is present in the exchange terms.
Analysis of the exchange processes allows to understand the most important features of the mechanism of scattering. In the Supplement, we provide examples when exact finite-range calculations following nucleon-nucleus kinematics are clearly superior to the zero-range treatment of knock-on exchange. Demonstration of the experiments presented here and their study could make it possible to more reliably consolidate in memory the formalism set forth in Lecture Course II.
Appendices 1 to 4 at the end of the Supplement provide abstracts of communications presented with the author’s participation at several International Conferences “NUCLEUS” on nuclear spectroscopy and nuclear structure.
This Supplement to Lecture Course II is aimed at researches and students studying experimental nuclear physics and nuclear engineering. Lecture Course II is available on the sites of the following scientific libraries: https://www.academia.edu; https://www.libmonster.ru; https://www.researchgate.net
Author(s) | Плавко А.В. / Plavko A.V. | ||
Number of Pages | 22 | ||
Date Published | 03.05.2022 |
Permanent link to this publication: https://libmonster.ru/m/book/view/Supplement-to-Lecture-Course-II-Nucleon-Nucleus-Kinematics-in-Proton-Scattering © libmonster.ru |
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