Direction of Polarization Produced by Quasi-Elastic Scattering of 315-Mev Protons

Abstract

Protons scattered quasi-elastically with energy 315 Mev at 13° from a beryllium target in the Berkeley synchrocyclotron were brought out of the machine, slowed by absorbers, and scattered in helium at 765 psi absolute pressure. Scattering events at angles of 90°±22.5° were detected in nuclear emulsions. Observed asymmetries in left versus right scattering of protons with energies below 14 Mev were used, in conjunction with phase shifts from $p$-He scattering data, to compute the direction of spin polarization. We find spin up from left scattering, in agreement with the predictions of spin-orbit coupling theory and with the findings of other experimenters.