[en] Radiative muon capture (RMC) on hydrogen produces photons with a yield of ≅ 10^-8 per stopped muon. To measure RMC at TRIUMF we have constructed a lage-solid-angle photon pair-spectrometer which surrounds the liquid hydrogen target. The spectrometer consists of a cylindrical photon converter and a larget-volume cylindrical drift chamber to track the e⁺e^- pairs. It is enclosed in a spectrometer magnet which produces a highly uniform axial magnetic field. The detector subsystems, the hardware trigger and the data acquisition system are described, chamber calibration and tracking techniques are presented, and the spectrometer performance and its Monte Carlo simulation are discussed. (orig.)

[en] In the Standard Model, the weak interaction is purely V-A in character. However in semileptonic reactions the strong force induces additional couplings. One of these, the induced pseudoscalar coupling g_p, is still very poorly determined experimentally. Using PCAC and the Goldberger-Treiman relation, one can obtain the estimate g_p/g_a = 6.8 for the nucleon. At present, the world average of 5 measurements of the rate of ordinary muon capture (each with an error in excess of 40%) yields g_p/g_a = 6.9 ± 1.5. Radiative Muon Capture (RMC) is considerably more sensitive to the pseudoscalar coupling. Due to the extremely small branching ratio (∼ 6 x 10^-8), the elementary reaction μ^-p→ μnγ has never been measured. Effort to date has concentrated on nuclear RMC where the branching ratio is much larger, but the interpretation of these results is hindered by nuclear structure uncertainties. A measurement is being carried out at TRIUMF to determine the rate of RMC on hydrogen to a precision of 8% leading to a determination of g_p with an error of 10%. The detection system is based on a large-volume drift chamber acting as a pair spectrometer. The drift chamber covers a solid angle of about 2π. At a magnetic field of 2.4 kG the acceptance for 70 MeV photons is about 0.9% using a 1.2 mm thick Pb photon converter. The expected photon energy resolution is about 10% FWHM. A detailed discussion of the systematic errors expected in the experiment and the preliminary results on the performance of the detector will be presented

[en] The induced pseudoscalar coupling constant, g_P, of the weak hadronic current can be determined from the measurement of the branching ratio of radiative muon capture (RMC) on hydrogen. This rare process is being investigated in the TRIUMF RMC experiment which is now taking data. This paper describes the experiment and indicates the status of the data analysis. (Author) 8 refs., 7 figs

[en] A brief review is made of the study of gp, the induced pseudoscalar coupling constant, in radiative muon capture on light nuclei, and of motivations for a measurement on hydrogen, with particular emphasis on recent and ongoing experiments at TRIUMF

[en] Radiative muon capture rates have been measured for carbon, oxygen and calcium targets. The carbon and oxygen rates yield large values for g_ρ when compared to detailed microscopic calculations but the conventional Goldberger-Treiman value when compared to phenomenological model calculations. A progress report on the TRIUMF RMC measurement on hydrogen is also given. (Author) 16 refs., 2 figs., tab

[en] The branching ratio for radiative muon capture (RMC), relative to the nonradiative process, is sensitive to g_p, the induced pseudoscalar coupling constant of the weak hadronic current. The photon energy spectra from RMC on ²⁷Al, ²⁸Si, ⁴⁰Ca, ^natMo, ^natSn, and ^natPb have been measured using a high-acceptance pair spectrometer. The measured partial branching ratios, R_γ, for photons of E_γ>57 MeV are 1.43±0.13, 1.93±0.18, 2.09±0.19, 1.11±0.11, 0.98±0.09, and 0.60±0.07 respectively, in units of 10^-5. The results confirm the previously observed suppression of R_γ with increasing Z for Z>20. For ⁴⁰Ca 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 g_p, but the more recent calculation does not reproduce the data for any value of g_p

[en] The radiative capture of negative muons by protons can be used to measure the weak induced pseudoscalar form factor. Brief arguments why this method is preferable to ordinary muon capture are given followed by a discussion of the experimental difficulties. The solution to these problems as attempted by experiment no. 452 at TRIUMF is presented together with preliminary results from the first run in August 1990. An outlook on the expected final precision and the experimental schedule is also given. (orig.)

[en] This paper reports on radiative muon capture rates measured for carbon, oxygen and calcium targets. The carbon and oxygen rates yield large values for g_p when compared to detailed microscopic calculations but the conventional Goldberger-Treiman value when compared to phenomenological model calculations. A progress report on the TRIUMF RMC measurements on hydrogen is also given

[en] The photon energy spectrum from the elementary process μ^-p→ν_μnγ was measured using a photon pair-spectrometer at the TRIUMF cyclotron. Various sources of backgrounds are discussed in detail and evaluated. From the final spectrum the partial branching ratio R_γ and the pseudoscalar coupling g_p were extracted. The values obtained are R_γ(k>60 MeV)=(2.10±0.21)x10^-8 and g_p(q²=-0.88m_μ²)=(9.8±0.7±0.3)g_a(0), respectively. The first error is the quadrature sum of statistical and systematic errors, while the second error is due to the uncertainty in λ_op, the transition rate of the pμp molecule from ortho to para states. This measurement of g_p, the most precise to date, agrees with all but one of the previous measurements. However it is 1.46 times the value predicted by the partially conserved axial current hypothesis and pion pole dominance. copyright 1998 The American Physical Society