Radiative muon capture on Al, Si, Ca, Mo, Sn, and Pb.

The branching ratio for radiative muon capture (RMC), relative to the nonradiative process, is sensitive to {ital g}{sub {ital p}}, the induced pseudoscalar coupling constant of the weak hadronic current. The photon energy spectra from RMC on {sup 27}Al, {sup 28}Si, {sup 40}Ca, {sup nat}Mo, {sup nat}Sn, and {sup nat}Pb have been measured using a high-acceptance pair spectrometer. The measured partial branching ratios, {ital R}{sub {gamma}}, for photons of {ital E}{sub {gamma}}{gt}57 MeV are 1.43{plus minus}0.13, 1.93{plus minus}0.18, 2.09{plus minus}0.19, 1.11{plus minus}0.11, 0.98{plus minus}0.09, and 0.60{plus minus}0.07 respectively, in units of 10{sup {minus}5}. The results confirm the previously observed suppression of {ital R}{sub {gamma}} with increasing {ital Z} for {ital Z}{gt}20. For {sup 40}Ca the present result is in good agreement with previous measurements. For the heavier nuclei, the results are compared with two recent calculations performed in the Fermi-gas model. In one case the data indicate a complete quenching of {ital g}{sub {ital p}}, but the more recent calculation does not reproduce the data for any value of {ital g}{sub {ital p}}.