Radiative neutron capture by deuterium

Abstract

The $^{2}$H(n,\ensuremath{\gamma}${)}^{3}$H reaction has been studied with polarized and unpolarized neutrons of energies ranging from 9 to 14 MeV. Angular distributions of cross section were measured at ${E}_{\mathrm{n}}$(lab)=9.0, 10.8, and 14.0 MeV, \ensuremath{\sigma}(90\ifmmode^\circ\else\textdegree\fi{}) was measured at 6.85 MeV, and an analyzing-power angular distribution was measured at 9.0 MeV. The results for \ensuremath{\sigma}(theta) agree with the existing $^{3}\mathrm{H}$(\ensuremath{\gamma},n${)}^{2}$H data after detailed balancing. The resulting $^{3}\mathrm{He}$(\ensuremath{\gamma},p)${/}^{3}$H(\ensuremath{\gamma},n) ratio for 90\ifmmode^\circ\else\textdegree\fi{} cross sections is 1.1\ifmmode\pm\else\textpm\fi{}0.15 down to ${E}_{x}$=10.8 MeV. The T-matrix analysis of the data indicates \ensuremath{\sim}3% for the E2 contribution to the capture cross section---comparable to that found earlier for $^{2}\mathrm{H}$(p,\ensuremath{\gamma}${)}^{3}$He and in contrast to the predictions [${\ensuremath{\sigma}}_{\mathrm{n}(\mathrm{E}2)/{\ensuremath{\sigma}}_{\mathrm{p}(\mathrm{E}2)}}$=1/25] of a two-body direct-capture calculation.