Quasi-free collisions of 400 MeV protons in deuterium and carbon

The first results from a program to compare quasi-free proton and neutron knockout from nuclei are presented. The binding energy of the s and p neutron hole states in 12C have been obtained. Relative cross sections for proton and neutron knockout from 2H and 12C were determined for two very diferent kinematical conditions. The ratio, R of sigma(p,pn) to sigma(p,2p) is in agreement with estimates based on the impulse approximation for 2H but there is a deviation for 12C. These observations suggest that refinements will have to be made to the theoretical ideas used to analyze quasi-free knockout reactions. (Auth.)