Muon Capture inHe3

Abstract

The rate has been measured for capture of negative muons on ${\mathrm{He}}^3$ to form bound ${\mathrm{H}}^3$. The monoenergetic recoil triton was observed in a ${\mathrm{He}}^3$ gas scintillation target counter, and the rate was normalized to $\mu$-decay electrons observed in surrounding counters. Triton pulses were analyzed in the two dimensions of energy and time with respect to the stopping muon, and with an ultimate energy resolution of 15%, full width at half-maximum, a clean separation could be made between recoil tritons and other muon-associated events. The measured capture rate is 1465±67 ${\sec }^{-1\mathrm{}}$, in good agreement with other experiments and with predictions based on the "standard" theory of muon capture. Simultaneous limits were calculated for the vector and induced pseudoscalar coupling constants, $g_V^{}{}_{}{}^{\mu }$ and $g_P^{}{}_{}{}^{\mu }$, using the results of this experiment and of the experiments on muon capture in liquid hydrogen. These are $0.7<\mathrm{}\frac{g_V^{}{}_{}{}^{\mu }}{g_V^{}{}_{}{}^{\beta }}<1.2\mathrm{}$ and $1<\mathrm{}\frac{g_P^{}{}_{}{}^{\mu }}{g_A^{}{}_{}{}^{\mu }}<17\mathrm{}$ with central values of 0.99 and 11.6, respectively.