Measurement of the Reactionμ−+C12→B12+ν

A measurement of the rates of negative muon absorption to particle-stable states of boron-12 has been performed with scintillation counters. In order to obtain the absorption rate to the ground state alone, a measurement was first performed of the absorption rate to all bound states of ${\mathrm{B}}^{12}$. Separation of the contribution from absorption to ${\mathrm{B}}^{12}$ excited bound states was then effected by observation of coincidences between nuclear de-excitation gamma rays and the ${\mathrm{B}}^{12}$ ion recoiling after muon absorption. The measured rate for muon absorption to the ground state of ${\mathrm{B}}^{12}$ is (${6750}_{-750\mathrm{}}^{+300\mathrm{}}$) ${\sec }^{-1\mathrm{}}$, in good agreement with prediction of the universal Fermi interaction.