W. R. Coker

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 We show direct comparisons, some previously unpublished, between the predictions of the best available nonrelativistic and relativistic scattering models and the data.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 differential cross sections and analyzing powers for p+40,42,44,48Ca at 0.8 GeV☆

Abstract Differential cross sections and analyzing powers for the elastic scattering of 800 MeV polarized protons from 40,42,44,48Ca are reported. A first-order, spin-dependent KMT optical potential analysis is presented from which the rms radii of the neutron densities are deduced. A comparison of these results with other determinations and with various theoretical predictions is given.

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 differential cross sections and analyzing powers for p + 54Fe, 58,64Ni at 800 MeV

Abstract Elastic scattering analyzing powers and differential cross sections for 800 MeV → p + 54Fe, 58,64Ni are reported. An approximately mode-independent technique is used to extract information concerning the neutron density distributions of these nuclei.

Analysis of elastic scattering of 0.8 GeV polarized protons from 116Sn and 124Sn

Abstract Differential cross section and analyzing power data for elastic scattering of 0.8 GeV polarized protons from 116Sn and 124Sn are analyzed in terms of a spin-dependent Kerman-McManus-Thaler formalism. Neutron matter densities and rms radii are deduced with careful attention to sources of error, and found to be in good agreement with Hartree-Fock predictions.

“Spin-orbit deformation” in inelastic scattering of protons at medium energies☆

Abstract Distorted-wave Born-approximation calculations for medium-energy proton inelastic scattering to collective states, which use microscopic, spin-dependent optical potentials that properly describe proton elastic analyzing powers, show that inclusion of the deformation or collectivity of the spin-orbit term in the inelastic transition matrix element has an important effect on predictions for the available inelastic angular distributions and analyzing powers.

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.

Phenomenological analysis of 4He + 4He scattering at 0.65 and 0.85 GeV☆

Abstract We present results of a phenomenological analysis of recently obtained data for 4He + 4He elastic scattering at 0.65 and 0.85 GeV incident laboratory energies. We find that the observed angular distributions cannot be fit unless the nuclear potential has a strong, short-range repulsive contribution, in agreement with the results of microscopic and phenomenological analyses of low energy 4He + 4He scattering.