Kinematical analysis of pion decay in flight: a new method for measuring the muon neutrino mass

Forward inflight decays of pions reveal information on the muon neutrino mass. In contrast to pion decay at rest in a stop target, the result is very slightly dependent on the uncertainty of the pion mass and on the theory of the momentum loss of muons in matter. In addition, relevant calibrations can be performed. A first test of the new method done at SIN is described.