ReactionLi6(n,p)He6at 118 MeV

Cross sections at six angles from 0° out to 20° in the c.m. system have been measured for the $1^{+}$ → $0^{+}$ transition in the reaction ${}_{}{}^6{}_{}{}^{}\mathrm{Li}\mathrm{}(n,p)\mathrm{}{}_{}{}^6{}_{}{}^{}\mathrm{He}$ at $E_n=118\mathrm{}$ MeV. The 0° cross section is in good agreement with measurements of the same quantity on ${}_{}{}^6{}_{}{}^{}\mathrm{Li}\mathrm{}(n,p)\mathrm{}{}_{}{}^6{}_{}{}^{}\mathrm{Be}$ at similar energies. The 0° ($n,p$) cross section gives a value of 161 ± 17 MeV ${\mathrm{fm}}^3$ for the volume integral of the central part of the spin-isospin interaction; a theoretical value of 161 MeV ${\mathrm{fm}}^3$ is in good agreement. A distorted wave calculation for a pure, Gamow-Teller transition is in fair agreement with the measured ($n,p$) angular distribution. An approximate resolution of the weak $1^{+}$ → $2^{+}$ transition to the first excited state of ${}_{}{}^6{}_{}{}^{}\mathrm{He}$ at 1.8 MeV shows an angular distribution of a very different character corresponding to a transition of mixed angular momenta.