Polarization in quasi-elastic (p, 2p) reaction on Li nucleus in complete kinematics at 1 GeV

Polarizations of the secondary protons from the (p, 2p) reactions on 7 Li nucleus at 1 GeV of the initial proton energy have been measured in a kinematically complete experiment. Two final protons from the reaction were detected in coincidence by means of a two-arm magnetic spectrometer at nonsymmetric scattering angles Θ 1 =15°÷26° and Θ 2 =58.6° in the momentum range of the residual nucleus up to 175 MeV /c . Both arms of the spectrometer were equipped with multiwire proportional chamber polarimeters. The resolution of the spectrometer on separation energy of 4.5 MeV (FWHM) was enough to reliably separate S- and P-shell recoil protons. The experimental data shows a strong deviation from a simple Impulse Approximation expectation, both for S- and P-shell (p, 2p) events. Analysis in the framework of the the Distorted Wave Impulse Approximation has been done in combination with depolarization factors, the latter being found by fits to the data. Simple estimations show that the experimentally found depolarization, in particular for the protons detected in the high-energy arm of the spectrometer, is too large. A significant reduction of the both detected proton polarizations might be explained in the frame of a recently developed approach based on modification of the pp-scattering amplitude in nuclear medium.