Measurement of the lifetime of the positive muon

The lifetime of the positive muon was measured using the synchrocyclotron of the Nuclear Problems Laboratory at the Joint Institute for Nuclear Research. The mean life of the positive muon was found to be 2.19711 ± 0.00008 JLsec. The decay positrons were registered with a Cerenkov counter, which had a water radiator that also served as the target and was so designed as to stop the muons at its center. The use of a positron detector with 41T geometry and a high recording efficiency considerably reduced the time required for accumulating adequate statistics and made it possible to avoid some spurious effects.