A measurement of the Wolfenstein R′ parameter in p-p scattering at 140 MeV

Abstract

Measurements have been made of the Wolfenstein R′ parameter at c.m. angles 31.4, 41.7, 52.0, 61.8, 72.1 and 82.2 degrees. The values obtained were +0.625±0.062, +0.548±0.062, +0.470±0.069, +0.343±0.058, +0.466±0.095 and 0.190±0.177, respectively. These values were deduced from asymmetry measurements which were proportional to the combination ( R cos θ S + R′ sin θ S) of the R and R′ parameters, where the spin precession angle θ S was approximately 45°. Previous determinations of the R parameter permitted the above values for R′ to be obtained from the data. These measurements were found to be in good agreement with the predictions of phase-shift analyses at 140 MeV.