Scattering of Polarized Neutrons from Heavy Nuclei

Abstract

The polarization of 400-kev $\mathrm{Li}(p, n)$ neutrons emitted at a laboratory angle of 50\ifmmode^\circ\else\textdegree\fi{} with respect to the incident proton beam was measured to be 53\ifmmode\pm\else\textpm\fi{}6 percent by determining the left-right asymmetry in the intensity of neutrons scattered at 90\ifmmode^\circ\else\textdegree\fi{} from oxygen. Oxygen scattering phase shifts necessary for this calculation were derived from the results of previous experiments.Left-right scattering asymmetries were measured for 11 elements, ranging in atomic weight from copper to bismuth. From these asymmetries the magnitudes of the polarizations caused by the heavy nuclei were determined. The variation of the polarization with atomic number appeared similar to that expected from the square well-with-absorption nuclear model of Feshbach, Porter, and Weisskopf, modified by the addition of a spin-orbit term equal to -1.5 Mev (1.s).