The radiative muon capture process has been observed in He-3 by detecting a high-energy photon in coincidence with the recoil triton. A cylindrical pair spectrometer and a scintillating liquid He-3 target were used to detect the photon and triton, respectively. The resulting photon spectrum is compared to impulse approximation calculations both with and without meson exchange corrections. The calculations over-estimate the measured spectrum by 30% and 20%, respectively. The recoil energy spectrum indicates that only 11% of the total radiative capture rate goes to final states which include deuterons and protons, with the remainder of the rate going to a triton final state.

The photon spectra from radiative muon capture (RMC) on O, Al, Si, Ti, Zr, and Ag have been measured for photon energies greater than 57 MeV using a cylindrical pair spectrometer at the TRIUMF cyclotron. Values of R-gamma, the ratio of the radiative rate for photon energies above 57 MeV, to the nonradiative rate, are 1.67 +/-0.18, 1.40+/-0.11, 2.09+/-0.20, 1.30+/-0.12, 1.31+/-0.15, and 1.12+/-0.13, respectively, in units of 10(-5). The Al/Si rate difference confirms an earlier result. The Ti/Ca rate difference and the rate suppression in Zr and Ag are new results which confirm that the RMC rate is a much smoother function of neutron excess than of atomic number. This suggests that Pauli blocking is relatively more important for radiative capture than for nonradiative capture. The value of the ratio of the induced weak pseudoscalar to axial coupling constants, g(p)/g(a), for O was found to be 4.9+/-0.6, 6.3+/-1.1, or 8.11(-2.1)(+1.8), depending on the theory used to extract it. These values are in good or fair agreement with the partially conserved axial-vector current (PCAC) hypothesis. For the other nuclei studied, large model dependences or a lack of detailed RMC calculations made tests of the PCAC hypothesis difficult. [S0556-2813(99)06305-0].

We report measurements of the photon rates and energy spectra from inclusive radiative muon capture on three nickel isotopes using a photon pair spectrometer at the TRIUMF cyclotron. The Values of R-gamma, the partial branching ratios of radiative muon capture for photon energies >57 MeV, for Ni-58.60,Ni-62 were found to be (in units of 10(-5)) 1.48 +/- 0.08, 1.39 +/- 0.09, and 1.05 +/- 0.06, assuming a Fermi-gas photon spectral shape. The results reveal a significant isotope effect in the nickel branching ratios and a simple empirical scaling of the present nickel and earlier nuclear R-gamma data with neutron excess. Furthermore, the observed atomic mass and neutron excess dependence of the entire nuclear R-y data set is well reproduced by a relativistic Fermi-gas calculation. The ability of the model to reproduce the Variation of the R-gamma data using the Goldberger-Treiman formula for g(P) suggests there is no compelling reason to invoke a more exotic A-dependent renormalization of g(P).