Measurement of the formation rate and the radiative decay of the muonic molecules [Formula Presented] and [Formula Presented]

Formation and decay of the [Formula Presented] and [Formula Presented] molecules have been studied in binary-gas mixtures of [Formula Presented] and [Formula Presented] 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 [Formula Presented] and [Formula Presented] The radiative branching ratios of the decay of the [Formula Presented] and [Formula Presented] 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.