Thermal Neutron Capture by Deuterium and Structure of the Three-Body Wave Function

The study of three-nucleon wave functions has recently drawn considerable attention owing to experiments on elastic scattering of high-energy electrons from ${\mathrm{H}}^3$ and ${\mathrm{He}}^3$. We attempt here to obtain independent information on these wave functions using the available experimental data on slow-neutron capture by deuterium. This reaction goes mainly through magnetic dipole radiation from both exchange and spin magnetic-moment interaction. Three types of three-body wave functions, Gaussian, Irving, and Irving-Gunn, are considered. An upper limit on the probability of the $S^{\prime }$ state of mixed symmetry (${}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$ state with $T=\frac{1}{2}$) is deduced from the experimental capture rate.