Measurement of the photon asymmetry in 40Ca(μ-, γsub(μ)γ)40K* by a stroboscopic method

Radiative muon capture exhibits a striking sensibility to the induced pseudoscalar part of the semileptonic weak interaction. Among the obervables the muon spin photon angular correlation distinguishes itself from the other measurable quantities such as the photon spectrum or the total reaction yield by its relatively small model dependence, i.e. the choice of the nuclear response function or higher order terms in the transition operator enter only as small corrections. In the absence of pseudoscalar coupling photons are preferentially emitted along the muon spin, the asymmetry parameter in the correlation function is equal to one, independent of energy. The authors report the results from a short feasibility study aimed at testing a novel technique as well as confirming the sign of the asymmetry parameter. (Auth.)