Using the Double Chooz detector, designed to measure the neutrino mixing angle ${\theta }_{13}$, the products of ${\mu }^{-}$ capture on ${}^{12}\mathrm{C},{}^{13}\mathrm{C},{}^{14}\mathrm{N}$, and ${}^{16}\mathrm{O}$ have been measured. Over a period of 489.5 days, $2.3\times {10}^6$ stopping cosmic ${\mu }^{-}$ have been collected, of which $1.8\times {10}^5$ captured on carbon, nitrogen, or oxygen nuclei in the inner detector scintillator or acrylic vessels. The resulting isotopes were tagged using prompt neutron emission (when applicable), the subsequent $\beta$ decays, and, in some cases, $\beta$-delayed neutrons. The most precise measurement of the rate of ${}^{12}\mathrm{C}({\mu }^{-},\nu ){}^{12}\mathrm{B}$ to date is reported: $6.{57}_{-0.21}^{+0.11}\times {10}^3{\mathrm{s}}^{-1}$, or $(17.{35}_{-0.59}^{+0.35})\%$ of nuclear captures. By tagging excited states emitting $\gamma \mathrm{s}$, the ground state transition rate to ${}^{12}\mathrm{B}$ has been determined to be $5.{68}_{-0.23}^{+0.14}\times {10}^3{\mathrm{s}}^{-1}$. The heretofore unobserved reactions ${}^{12}\mathrm{C}({\mu }^{-},\nu \alpha ){}^8\mathrm{Li},{}^{13}\mathrm{C}({\mu }^{-},\nu n\alpha ){}^8\mathrm{Li}$, and ${}^{13}\mathrm{C}({\mu }^{-},\nu n){}^{12}\mathrm{B}$ are measured. Further, a population of $\beta n$ decays following stopping muons is identified with $5.5\sigma$ significance. Statistics limit our ability to identify these decays definitively. Assuming negligible production of ${}^8\mathrm{He}$, the reaction ${}^{13}\mathrm{C}({\mu }^{-},\nu \alpha ){}^9\mathrm{Li}$ is found to be present at the $2.7\sigma$ level. Limits are set on a variety of other processes.

• Received 23 December 2015
• Revised 9 March 2016

DOI:https://doi.org/10.1103/PhysRevC.93.054608