On the muon neutrino mass

Angelov, N.; Balestra, F.; Batusov, Yu.; Bianconi, A.; Bussa, M. P.; Busso, L.; Ferrero, L.; Garfagnini, R.; Gnesi, I.; Rizzini, E. Lodi; Maggiora, A.; Panzieri, D.; Piragino, G.; Pontecorvo, G.; Tosello, F.; Venturelli, L.

On the muon neutrino mass

Authors

Description

During the runs of the PS 179 experiment at LEAR of CERN, we photographed an event of antiproton-Ne absorption, with a complete pi+ -> mu+ ->e+ chain. From the vertex of the reaction a very slow energy pi+ was emitted. The pi+ decays into a mu+ and subsequently the mu+ decays into a positron. At the first decay vertex a muon neutrino was emitted and at the second decay vertex an electron neutrino and a muon antineutrino. Measuring the pion and muon tracks and applying the momentum and energy conservation and using a classical statistical interval estimator, we obtained an experimental upper limit for the muon neutrino mass: m_nu < 2.2 MeV at a 90% confidence level. A statistical analysis has been performed of the factors contributing to the square value of the neutrino mass limit.
18 pages, 5 eps figures