Measurement of the formation rate and the radiative decay of the muonic molecules (pμ^{3}He)^{} and (pμ^{4}He)^{} (original) (raw)

Formation and decay of the (p 3 He͒* and (p 4 He͒* molecules have been studied in binary-gas mixtures of H 2 ϩ 3 He and H 2 ϩ 4 He at 30 K. The muon ground-state transfer rates from hydrogen to the two helium isotopes were extracted from the time distribution of the 7-keV decay x rays of the muonic hydrogen-helium molecules, measured with a Ge detector. The obtained transfer rates are p 3 He ϭ(0.46Ϯ0.15)ϫ10 8 s Ϫ1 and p 4 He ϭ(0.42Ϯ0.07)ϫ10 8 s Ϫ1. The radiative branching ratios of the decay of the (p 3 He͒* and (p 4 He͒* molecules were determined by comparing the yields of the Lyman series of muonic hydrogen with the one of the 7-keV line with charge-coupled-device detectors. The ratios are in agreement with theoretical predictions. Muon transfer from excited states of muonic hydrogen to both helium isotopes was also observed.