Sunday, September 25, 2011

Relativistic Time Dilation in Muon Decay

See: Relativistic Time Dilation in Muon Decay

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Muons reveal the interior of volcanoes

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It has been recently shown that puzzling excess events observed by the LSND and MiniBooNE neutrino experiments could be interpreted as a signal from the radiative decay of a heavy sterile neutrino (nu_h) of the mass from 40 to 80 MeV with a muonic mixing strength ~ 10^{-3} - 10^{-2}. If such nu_h exists its admixture in the ordinary muon decay would result in the decay chain mu -> e nu_e nu_h -> e nu_e gamma nu. We proposed a new experiment for a sensitive search for this process in muon decay at rest allowing to definitively confirm or exclude the existence of the nu_h. To our knowledge, no experiment has specifically searched for the signature of radiative decay of massive neutrinos from muon decays as proposed in this work. The search is complementary to the current experimental efforts to clarify the origin of the LSND and MiniBooNE anomalies. Bounds on the muonic mixing strength from precision measurements with muons are discussed. See: New muon decay experiment to search for heavy sterile neutrino and also The LSND/MiniBooNe excess events and heavy neutrino from muon and kaon decays

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Some History of the Muon Experiment

The historical experiment upon which the model muon experiment is based was performed by Rossi and Hall in 1941. They measured the flux of muons at a location on Mt Washington in New Hampshire at about 2000 m altitude and also at the base of the mountain. They found the ratio of the muon flux was 1.4, whereas the ratio should have been about 22 even if the muons were traveling at the speed of light, using the muon half-life of 1.56 microseconds. When the time dilation relationship was applied, the result could be explained if the muons were traveling at 0.994 c.

In an experiment at CERN by Bailey et al., muons of velocity 0.9994c were found to have a lifetime 29.3 times the laboratory lifetime.