Relativistic calculations for photonuclear reactions (III): A consistent relativistic analysis of the (e, e′p) and (γ, p) reactions

Abstract

Single nucleon knockout reactions must be described in a consistent framework in order to extract information about nuclear structure and reaction mechanisms. Consistent relativistic models for the direct knockout contribution to the (e, e ′ p) and (γ, p) reactions have been developed and used previously to examine existing momentum distribution and cross section data for the two reactions 1 . We present results of calculations of spin observables obtained from these models of (e, e ′ p) and (γ, p) reactions. For the (e, e ′ p) reaction we consider the importance of the choice of kinematics and show that perpendicular kinematics result in distributions with relatively large cross sections and comparatively large polarizations. In the (γ, p) reactions the photon asymmetry and proton polarization are not very sensitive to changes in model ingredients when the incident photon energy is less than 100 M eV . For higher energies these observables show increasing sensitivity to modifications of both the bound and continuum wave functions.

Overlap functions in correlation methods and quasifree nucleon knockout from16O

“…They are certainly dominant in the (γ, n) reaction, where the DKO mechanism, even in its most sophisticated version [37], gives but a small fraction of the experimental cross sections, while for the (γ, p) reaction the contribution of DKO is much more relevant. Nonrelativistic DWIA calculations, based on the same approach presented in Section 2.1 for the (e, e ′ N ) reaction [38], and more recent relativistic calculations, also based on the DKO mechanism [39], are able to give a fair description of data. The results, however, are very sensitive to the theoretical ingredients adopted for bound and scattering states.…”

Relativistic eikonal approximation in high-energyA(e,e′p)reactions

“…So far no approximations have been made. Various groups [17][18][19] have solved the Dirac equation (28) for the final scattering state using Dirac optical potentials derived from global fits to elastic proton scattering data [20]. Not only are global parametrizations of Dirac optical potentials usually restricted to proton kinetic energies T p ≤ 1 GeV, calculations based on exact solutions of the Dirac equation frequently become impractical at higher energies.…”

Relativistic formulation of Glauber theory for A(e,e′p) reactions

“…A concerted research effort which started back in the late eighties has resulted in the development of a number of relativistic DWIA (RDWIA) models for computing A(e, e p) observables [11][12][13][14][15]. These theoretical efforts very much followed the trend of developing relativistic models for p + A → p + A processes as a potential improvement to the traditional non-relativistic distorted-wave approaches.…”

“…Next, we introduce the relativistic formulation of Glauber multiplescattering theory in Section 3. Section 4 is devoted to a presentation of results for the DiracGlauber phase for the nuclei 4 He, 12 C, 56 Fe and 208 Pb. Hereby, a relativistic independentparticle model will be adopted.…”

“…The Dirac-Glauber phase is a function which accounts for all FSI effects when computing the A(e, e p) observables. The contribution of single-and multiple-scatterings is estimated for the target nuclei 4 He, 12 C and 208 Pb. Attention is paid to the role of relativistic effects when computing the impact of final-state interactions.…”