Analyzing power and cross section distributions of the knockout reaction ²⁰⁸Pb(p^→2p)²⁰⁷Tl at an incident energy of 202 MeV

Exclusive measurements of the cross section and analyzing power for the ²⁰⁸Pb(p^→2p)²⁰⁷Tl proton knockout reaction at 202 MeV are presented for three quasifree angle pairs. Energy-sharing cross section distributions are found to be in excellent agreement with distorted wave impulse approximation (DWIA) calculations, yielding spectroscopic factors that are in reasonable agreement with (e,e′p) studies and theoretical expectations. The measured analyzing powers are, however, in significant disagreement with results of standard DWIA calculations that utilize the free nucleon-nucleon interaction. Analyzing power calculations are furthermore found to be insensitive to variations in the distorting potentials, different descriptions of the bound state, different energy prescriptions of the two-body interaction, and nonlocality effects. Agreement between theory and experiment is shown to improve only when the density dependence of the nucleon-nucleon interaction is incorporated within the DWIA.