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 time-of-flight 
stations (with resolutions up to 50-60 ps), two Aerogel Cerenkov counters 
and a KLOE-like calorimeter (KL) has been constructed and has allowed the 
commissioning of the MICE muon beamline in 2010 and a first measurement of 
emittance. Detector performances will be shown and their use for the 
beamline characterization fully illustrated.