Proton-induced nucleon knockout from 40Ca in the dirac impulse approximation

Abstract

The (p, 2p) reaction on 40Ca at incident proton energies of 200 and 300 MeV is examined within a Dirac distorted-wave impulse approximation. The formalism is similar to that developed by Cooper and Maxwell except that the relativistic Love-Franey t-matrixis evaluated at the nucleon-nucleon laboratory energy (as defined within the plane-wave approximation), rather than the nucleon-nucleus laboratory energy, as by Cooper and Maxwell. Particular attention is paid to the sensitivity of the calculated cross sections and analyzing powers to the properties of the bound states employed. It is found that the analyzing powers depend very little on the bound-state properties, while the cross sections depend significantly only on the r.m.s. radii of the bound-state wave functions. A major success of the model is its ability to fit the cross-section data over a particular range of momentum transfers at both 200 and 300 MeV with the same bound-state potential. Outside this momentum transfer range, the predicted cross sections are too low. The calculated analyzing powers agree well with the data at 200 MeV, but disagree with the data at 300 MeV. Values for the r.m.s. radii of the 1 D 3 2 and 1 D 5 2 states in 40Ca are derived from the requirement that the peak positions of the calculated cross sections at 300 MeV agree with the empirical peak positions. Some preliminary results are also reported for neutron knockout from 40Ca at 150 MeV.