Polarization of Neutrons and Protons by Scattering

Abstract

Neutrons and protons can be polarized by scattering provided there is a spin-orbit interaction between the incident particle and the scattering nucleus. The polarization effect has been found for a nucleus of spin zero allowing for the possibility of resonance scattering. Particular attention has been paid to the resonance scattering of neutrons by ${\mathrm{He}}^4$ where almost full polarizations can be obtained, together with large cross sections. The polarization can be detected by a double scattering experiment, since the second scattering will be axially asymmetric with respect to the direction of the first scattered neutron. The existence of this effect and a preliminary treatment of it was first pointed out by Schwinger.