Feasibility of an experiment to determine the branching ratio for the emission of a heavy neutrino after muon capture in3He

The triton energy of the muon capture reaction μ3He → t+vμ, where μ3 He is the ground state of muonic3He, has been measured in order to investigate a possible heavy v admixture into the μ flavour with high sensitivity. μ3 He has been formed via the pμd fusion reaction by stopping μ− in an ionization chamber (IC) filled with an H/D gas mixture of 3% D concentration at a pressure of 161 bar. In a first short experiment 650 triton events were observed yielding an upper limit for the μ-heavy v mixing strength of 2.3×10−3 atE0v=60 MeV.