A study of nucleon properties in nuclei through (p, 2p) reactions

The differential cross sections and analyzing powers have been measured for a proton knockout reaction from s_1/2 orbits of several target nuclei aiming at studying nuclear medium effects in the nucleon-nucleon interaction, and in-medium nucleon properties through it. It is confirmed from the cross section data that the reaction mechanism is simple and contribution from the multi-step processes is less than ten percent, only a few percent for a ¹²C target case. The analyzing power shows a distinct reduction from the value of the free proton-proton scattering and the target dependence, which is equivalent to the density dependence, of the reduction suggests existence of a medium effect. The study has been extended to the measurement of other spin observables, polarization and spin-transfer coefficients, and a preliminary result is given.