Asymmetry Measurements in the Scattering of 155-Mev Neutrons by Carbon, Aluminum, Copper, Cadmium, and Lead

Abstract

The asymmetry in the scattering of a 13% polarized (155±5)-Mev neutron beam from C, Al, Cu, Cd, and Pb was measured at angles below the first maximum in the asymmetry. The scattered neutrons were detected by a large volume scintillator with an energy threshold determined by pulse-height discrimination. Optical-model calculations were performed by a WKB phase-shift analysis to find the "best fit" to the 155-Mev proton-carbon polarization data from Uppsala. The nuclear parameters determined in this manner were then used to calculate the polarization and the cross sections by WKB and Born approximations for comparison with the data of this experiment. The neutron polarization and the qualitative behavior of the neutron differential cross sections were well explained by the model, but sizable discrepancies were found between the predicted and measured absolute cross sections.