Negative Pion Capture in Helium

The capture rates of negative pions in ${\mathrm{He}}^4$ into the three modes $t+n$, $d+2n$, and $p+3n$ are calculated phenomenologically, using a two-nucleon capture model. The amplitudes which appear in the phenomenological interaction are evaluated by a comparison with the pion production cross sections; and the capture rates are compared with experiment. The calculated ratio of the triton mode to all captures within the energy range observed by Schiff, Hildebrand, and Giese is 30%, which is in good agreement with the experimental ratio of $\frac{1}{3}$.