Polarization transfer in inelastic proton scattering

Abstract

A new polarimeter technique which allows essentially unrestricted examination of polarization transfer in inelastic proton scattering is presented. This polarimeter system has been used to measure polarization transfer in a number of reactions in light nuclei. The data is compared to properly antisymmetrized distorted wave calculations which use realistic nucleon-nucleon effective interactions. Because of ambiguities surrounding interpretation of polarization transfer data, the connection between polarization transfer and spin-flip probability is drawn. The interpretation of spin-flip probability is more easily extended to cover situations where gross discrepancies between the data and the calculations were observed. Spin-flip probability is shown to be a simple quantity which is determined primarily by the spin transfer in a reaction. The spin-flip probability characteristic of specific angular momentum transfers (LSJ) is derived. For most of the transitions examined, uncertainties in the reaction mechanism limit the reliability of conclusions drawn solely on the basis of the spin-flip probability. However it is shown that the spin-flip cross section (the product of the spin-flip probability and the differential cross section) is relatively free from uncertainties in the reaction mechanism and is sensitive only to the single-step spin-transfer (S=l) amplitudes. This allows the direct comparison of the calculated spin-flip cross section to experiment. Discrepancies between these values must be taken seriously. For some transitions, the theory provides an adequate description of the reaction. For other transitions however, the gross discrepancy between the data and the calculations can be traced directly to inadequacies of the nuclear wavefunctions.