Cross-Section and Polarization Measurements for theH3(He3,n)Li5Reaction

Measurements of the angular distribution and polarization of neutrons from the reaction ${}_{}{}^3{}_{}{}^{}\mathrm{H}({}_{}{}^3{}_{}{}^{}\mathrm{He},n){}_{}{}^5{}_{}{}^{}\mathrm{Li}$ have been made for mean ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ bombarding energies of 2.70 and 3.55 MeV. Polarizations were measured using a ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ gas scintillator, and cross sections were determined using a liquid scintillator employing pulse-shape discrimination. Contributions from the three-body breakup channel ${}_{}{}^3{}_{}{}^{}\mathrm{H}({}_{}{}^3{}_{}{}^{}\mathrm{He},np){}_{}{}^4{}_{}{}^{}\mathrm{He}$ were removed by assuming these neutrons to be unpolarized and to have a statistical energy distribution in the high-energy portion of the neutron spectrum. The angular distribution of neutrons from the reaction ${}_{}{}^3{}_{}{}^{}\mathrm{H}({}_{}{}^3{}_{}{}^{}\mathrm{He},n){}_{}{}^5{}_{}{}^{}\mathrm{Li}$ exhibits a broad peak in the vicinity of ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}={45}^{\circ }$. The neutron polarization was found to be negative at all angles investigated, and reaches a minimum value of -0.30 at ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}={125}^{\circ }$, $E_{3\mathrm{He}}=2.7\mathrm{}$ MeV. Excitation functions for the cross section were measured at laboratory angles of 0 and 40° for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ energies between 0.7 and 3.8 MeV. The reaction data can be reproduced qualitatively with a simple two-nucleon-transfer distorted-wave Born-approximation calculation, but the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^3{}_{}{}^{}\mathrm{H}$ potential parameters used do not reproduce published elastic scattering data at somewhat higher energy.