Polarization in neutron-proton scattering at 29.6 MeV

Abstract

The polarization in neutron-proton scattering at 29.6 MeV was deduced from asymmetries measured at every 10\ifmmode^\circ\else\textdegree\fi{} c.m. from 50 to 150\ifmmode^\circ\else\textdegree\fi{} c.m. The incident neutron beam was derived from a high-pressure deuterium gas cell via the $^{2}\mathrm{H}(d, n)^{3}\mathrm{He}$ reaction at 37\ifmmode^\circ\else\textdegree\fi{} c.m. The beam passed through a spin rotation magnet and, at the target location 5.4 m from the gas cell, possessed a flux of 5 \ifmmode\times\else\texttimes\fi{} ${10}^{5}$ n/sec and a polarization of 0.32 \ifmmode\pm\else\textpm\fi{} 0.04. Data between 50 and 110\ifmmode^\circ\else\textdegree\fi{} c.m. were obtained using scintillating CH target in coincidence with neutron detectors, while data between 120 and 150\ifmmode^\circ\else\textdegree\fi{} c.m. were obtained using recoil protons from a C${\mathrm{H}}_{2}$ target. Total errors in the derived polarizations ranged from \ifmmode\pm\else\textpm\fi{} 0.007 to \ifmmode\pm\else\textpm\fi{} 0.022. These data agree very well with three previous values measured near 30 MeV at Los Alamos, but they disagree with Harwell data indicating small or negative polarizations near 150\ifmmode^\circ\else\textdegree\fi{} c.m. The present results agree well with predictions of the Livermore X and Yale IV phase shift sets, but slightly favor the former.NUCLEAR REACTIONS $^{1}\mathrm{H}(n, n)$, $E=29.6$ MeV; $P(\ensuremath{\theta})$, ${\ensuremath{\theta}}_{c}=50, 60, 70, 80, 90, 100, 110, 120, 130, 140, \mathrm{and} 150\ifmmode^\circ\else\textdegree\fi{}$; deduced Legendre coefficients.