A new spectrometer for muon spin rotation

We report on the development of a spectrometer for Muon Spin Rotation based on multiwire proportional chambers. The coordinates provided by telescopes each composed of two chambers are used to reconstruct the muon and the positron trajectories in⁺e⁺+v_e+ decay. A real-time analysis program verifies that the two tracks intersect within the target: this constitutes a very stringent test to veto events which do not correspond to a muon decay. The results of some experiments are given in order to illustrate the field of application of this spectrometer.