L. Ray

Nonrelativistic and relativistic descriptions of proton nucleus scattering

Abstract Historically, work in medium energy nucleon-nucleus scattering physics started in the 1950s and has continued since. During the past ten years exciting new developments have occurred, and this work reviews these developments. Two distinct theoretical approaches for describing the medium energy scattering process are discussed. The first is nonrelativistic and is based on approximate solutions to the many-body Schrodinger equation. The second is relativistic and is based on covariant meson exchange theory and the Dirac equation. A pedagogical discussion of nonrelativistic multiple scattering formalisms is presented, followed by a description of the approximation schemes used in numerical applications of the theory. Recent theoretical developments in the nonrelativistic approach, including medium corrections to the effective projectile-target nucleon interaction, off-shell contributions, and full integration (“full-folding”) of the nucleon-nucleus optical potential are discussed in detail. The historical development of the relativistic scattering models for the nucleon-nucleus system is reviewed and each of the principal models developed during the past ten years is explained, starting with the original relativistic impulse approximation model. We show direct comparisons, some previously unpublished, between the predictions of the best available nonrelativistic and relativistic scattering models and the data. A number of specific proton-nucleus elastic scattering cases are considered, including p+ 16 O, 40 Ca and 208 Pb at incident proton laboratory energies of 200, 500 and 800 MeV. Both relativistic and nonrelativistic approaches provide surprisingly similar and fairly good overall descriptions of the data. Finally, possible areas of further theoretical work in this field are discussed.

Elastic scattering of 0.8-GeV protons from C12, Ni58, and Pb208

Differential cross sections for elastic scattering of 0.8-GeV protons from /sup 12/C, /sup 58/Ni, and /sup 208/Pb have been measured. Preliminary analysis of the data in terms of the Kerman-McManus-Thaler formalism with spin-dependent nucleon-nucleon amplitudes shows sensitivity to details of proton and neutron matter distributions.

Theoretical and Experimental K+ + Nucleus Total and Reaction Cross Sections from the KDP-RIA Model

The 5-dimensional spin-0 form of the Kemmer-Duffin-Petiau (KDP) equation is used to calculate scattering observables [elastic differential cross sections (dσ/dΩ), total cross sections (σTot ), and total reaction cross sections (σReac)] and to deduce σTot and σReac from transmission data for K + + 6 Li, 12 C, 28 Si and 40 Ca at several momenta in the range 488– 714 MeV/c. Realistic uncertainties are generated for the theoretical predictions. These errors, mainly due to uncertainties associated with the elementary K + + nucleon amplitudes, are large, which may account for some of the disagreement between experimental and theoretical σTot and σReac. The results suggest that the K + + nucleon amplitudes need to be much better determined before further improvement in the understanding of these data can occur.

DWBA approach to inelastic scattering at medium energies

Abstract Medium energy proton elastic and inelastic scattering to states of 58 Ni and 208 Pb, and 4 He elastic and inelastic scattering to states of 40 Ca, are analyzed using the partial wave approach, by solving the Schrodinger equation with relativistic kinematics and using the distorted wave Born approximation. Our results can be compared with results of several previous analyses of the nucleon inelastic data using the Glauber approximation. Our calculations are absolute, using nuclear collective parameters obtained from a survey of a large number of low-energy analyses of inelastic scattering of electrons, nucleons and nuclei from 40 Ca, 58 Ni and 208 Pb.

Elastic scattering of 0.8 GeV polarized protons from 46,48Ti☆

Abstract Differential cross sections and analyzing powers for elastic scattering of 800 MeV polarized protons from 46,48Ti have been measured at laboratory angles ranging between 4° and 21°. The data are analyzed within the spin-dependent KMT formalism. Neutron density distributions are extracted and compared with the results of other experiments and with theoretical predictions. Disagreements between empirical results and DME calculations are found.

Large angle proton + Pb 208 elastic scattering at 800 MeV

A variety of nuclear structure and proton-nucleus dynamical effects are shown to significantly influence the behavior of the large angle 800 MeV p+ /sup 208/Pb elastic angular distribution. While coupled channels effects are found to be important, they are significantly smaller than recently suggested.

Spin-orbit deformation effects in (p,ṕ) from non-spherical nuclei at intermediate energies

Abstract Deformed spin-orbit, coupled-channels effects are investigated for 800 MeV proton inelastic scattering from 24 Mg and 154 Sm. The influence of the spin-orbit potential on the inelastic angular distributions and on the deduced multipole moments of the optical potential is shown to be small. The predicted 4 + and 6 + inelastic analyzing powers are, however, significantly affected by deformed spin-orbit coupling, multistep processes, and the large intrinsic quadrupole deformation of these two nuclei.

Relative sensitivities of medium energy K+ + nucleus and p + nucleus elastic angular distributions to neutron density distributions

Abstract A comparison of the relative sensitivities of 800 MeV proton-nucleus and 444 and 991 MeV K+ meson-nucleus elastic angular distributions to realistic details of neutron density distributions is presented for nuclei 40, 48Ca. The quantitative conclusions agree with qualitative expectations that medium energy K+ mesons are potentially superior at probing the nuclear interior, while medium energy protons are superior at probing the nuclear surface region.

Elastic scattering of polarized protons at 200 to 500 MeV

We have measured proton elastic scattering cross sections and analyzing power angular distributions on Ca and 208Pb at 200, 300, 400, and 500 MeV. The 400 MeV data from 208Pb have been fitted by an optical model and also compared with results of Impulse Approximation calculations.

Inclusive quasielastic spin observables for p+2H, 12C at 500 Me V☆

Abstract Analyzing powers (Ay) and spin-rotation-depolarization parameters (DSS, DSL, DLS, DLL, DNN) were determined for 500 MeV p + 2 H and p + 12 C inclusive quasielastic scattering at 10°, 15°, and 20° laboratory scattering angles. The p + 2 H data are consistent with the isospin-average of the proton-proton and proton-neutron scattering observables; the p + 12 C data are not. A relativistic plane wave impulse approximation calculation leads to better agreement with the p + 12 C spin-observables.