The NA62 RICH detector

The NA62 experiment at CERN aims at measuring the ultra-rare decay with a 10% accuracy; the main background is K+→μ+ν which is suppressed by means of kinematical cuts and by the different stopping power of μ+ and π+. A further 0.5%μ+ suppression must be provided by a RICH detector in a momentum range between 15 and 35 GeV/c. In this paper a RICH filled with Neon at atmospheric pressure contained in a 17 m long, 3 m wide vessel and in which the Cherenkov light is readout by 2000 single-anode photomultipliers, will be described. The results of a test beam performed with a prototype will be presented.