The MICE beamline PID instrumentation for a precise emittance measurement.

The International Muon Ionization Cooling Experiment (MICE) will carry out

a systematic investigation of ionization cooling of a muon beam, for the

future Neutrino Factory and the Muon Collider. As the emittance measurement

will be done on a particle-by-particle basis, a sophisticated beam 

instrumentation is needed to measure both particle coordinates and timing 

vs RF in a harsh environment due to high particle rates, fringe magnetic 

fields and RF backgrounds. A PID system, based on three x/y time-of-flight 

stations (with resolutions around 50 ps), two Aerogel Cerenkov counters and 

a KLOE-like calorimeter (KL) has been constructed and has allowed the 

commissioning of the MICE muon beamline. 

PID detector performances will be shown and their use for a preliminary

estimate of the beamline emittance and the MICE muon beam pion contamination

will be illustrated.