γ rays from muon capture in natural Ca, Fe, and Ni

Abstract

A significant improvement has been made in the identification of \ensuremath{\gamma} rays from muon capture in natural Ca, and to a lesser extent for Fe and Ni. For calcium, capture was observed in $^{44}\mathrm{Ca}$ and even $^{42}\mathrm{Ca}$, as well as the dominant $^{40}\mathrm{Ca}$. The (${\ensuremath{\mu}}^{\ensuremath{-}},\ensuremath{\nu})$ reaction was clearly observed in $^{40}\mathrm{Ca}$, but, as in the past, no clear identification was made in Fe and Ni. The (${\ensuremath{\mu}}^{\ensuremath{-}},\ensuremath{\nu}n$) reaction was clearly observed in all nuclei, and the \ensuremath{\gamma} rays observed correspond better to the ($\ensuremath{\gamma},p$) reaction than to spectroscopic factors from the ($d,$$^{3}\mathrm{He}$) or ($t,\ensuremath{\alpha})$ reactions. Some (${\ensuremath{\mu}}^{\ensuremath{-}},\ensuremath{\nu}2n$) and other reactions have been observed at a lower yield.