Kinetics of muonium formation in liquid helium

The spatial distribution of electron-muon pairs in superfluid helium (He-II) is determined using a new algorithm for reconstructing the muonium (Mu) formation probability. It is shown that because a gap is present in the excitation spectrum of He-II the thermalization time of muons and secondary electrons increases with decreasing temperature. As a result, the average distance in the electron-muon pairs increases and, correspondingly, the muonium formation rate decreases. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 3, 251–256 (10 February 1999)