Muonic Molecules in Liquid Hydrogen

We have studied the yield and time distribution of 5.5-MeV gamma rays from the fusion reaction p+d→He³+γ. The reaction was catalyzed by muons from the Nevis synchrocyclotron which were stopped in a target containing high-purity liquid hydrogen. A digitron of 30-nsec resolving time was used to study the yield of gamma rays as a function of the time that elapsed between the stopping of a muon and the emission of a gamma ray and as a function of the deuterium concentration, which was varied from 1 ppm to 25%. Analysis of the experimental distributions gives rates (in sec^-1) for the following muonic molecular processes: pμ+p→pμp, λₚₚ=(1.89±0.20)×10⁶, pμ+d→dμ+p, λₑ=(1.43±0.13)×10¹⁰, dμ+p→pμd, λpd=(5.80±0.30)×10⁶, pμd→He³+γ, λf=(0.305±0.010)×10⁶. The yield of fusion gamma rays was observed to increase with increasing deuterium concentration until it reached a saturation value of (14.0±{}2.4)% at 1% concentration. At 25% deuterium concentration the yield was observed to increase by a factor of 1.17±{}0.01 above the saturation yield. This effect is in agreement with a prediction of Wolfenstein and Gershtein. When neon was in solution in the hydrogen at a concentration of 1%, all of the muons transferred to the neon and the disappearance rate of muons bound to neon was measured to be (0.658±{}0.010)×{}10⁶ sec^-1.