Measurements of Charged Current Reactions of $\hat{I}{½}_e$ on ${}^{12}C$

Abstract

Charged Current reactions of $\hat{I}{½}_e$ on ${}^{12}C$ have been studied using a $\hat{I}{¼}^{+}$ decay-at-rest $\hat{I}{½}_e$ beam at the Los Alamos Neutron Science Center. The cross section for the exclusive reaction ${}^{12}C(\hat{I}{½}_e,e^{-}{)}^{12}{N}_{g.s.}$ was measured to be $(8.9\pm 0.3\pm 0.9)\times 10^{-42}$ cm${}^2$. The observed energy dependence of the cross section and angular distribution of the outgoing electron agree well with theoretical expectations. Measurements are also presented for inclusive transitions to ${}^{12}N$ excited states, ${}^{12}C(\hat{I}{½}_e,e^{-}{)}^{12}{N}^{\ast }$ and compared with theoretical expectations. The measured cross section, $(4.3\pm 0.4\pm 0.6)\times 10^{-42}$ cm${}^2$, is somewhat lower than previous measurements and than a continuum random phase approximation calculation. It is in better agreement with a recent shell model calculation.

34 pages, 18 figures, accepted to PRC, replaced with the accepted one