ELECTRON COULOMB EFFECTS IN QUASI-ELASTIC (E,E'P) REACTIONS

We describe a calculation for the electron Coulomb distrotion effects in (e,e'p) in the quasielastic region from medium and heavy nuclei. The bound nucleons are described by single-particle Dirac wave functions in the presence of scalar and vector potentials which are parameterized fits to relativistic Hartree potentials, while the wave function of the knocked-out nucleon is a solution to the Dirac equation with the relativistic optical potential. The electron wave functions are solutions to the Dirac equation in the presence of the Coulomb potential of the nuclues and the interaction with the selected nucleon is treated to first order. We examine the Ca-40(e,e'p) reaction in both parallel and omega-q constant kinematics. We find that electron Coulomb distortion has a smaller effect in omega-q constant kinematics than in parallel kinematics. The principal effect in parallel kinematics is to shift the maximum and minimum of the reduced cross section which is consistent with the experimental data. Occupation numbers of about 70% to 80% are needed to normalize the distorted-wave Born approximation calculation to the Ca-40(e, e'p) experimental data. We also calculate the reduced cross section for the 3s1/2 state in Pb-208 and compare our results to experimental data and previous calculations. We find no significant difference in using relativistic, as compared with nonrelativistic, nuclear wave functions. We do find significant corrections to earlier methods of treating Coulomb distortion which, in turn, affect the occupation number extracted from experiment. We find an occupation number for this state of 71.4%.