Search for Admixture of Massive Neutrinos in the Decay, pi Implies mu nu

摘要

In recent years interest in the question of whether neutrinos are truly massless has been rekindled, both by the development of a theory to unify the weak and electromagnetic interactions and by experimental observations. Some models based on the unified theory support the existence of neutrino mass. Direct measurement of the electron neutrino mass has resulted in an, as yet unconfirmed, value of 14 to 16 eV/c exp 2 . A measurement of the muon neutrino mass set an upper limit of 0.5 MeV/c exp 2 . An indirect argument for neutrino mass arises from the experimental observation of Davis et al., that there are too few electron neutrinos reaching the earth from the sun. This might be explained by invoking a neutrino oscillation process, which requires that neutrinos have mass. Terrestrial searches for neutrino oscillation have so far been inconclusive. An experiment to measure the muon energy for determining the neutrino mass in the pion decay pi exp -+ implies mu exp -+ + anti nu/sub mu / is described. We have developed a system for stopping the pions in a high purity (intrinsic), totally depleted, Germanium detector. With this apparatus we were able to measure the muon energy with a resolution of 7 keV, corresponding to a mass resolution of delta m/sub nu/ approx. 2 MeV/c exp 2 . Results are presented. (ERA citation 08:050161)