The NA62 RICH Detector

The CERN NA62 experiment aims to measure the ultra-rare charged kaon decay K+ → π+νν (branching fraction O(10-10)) with a 10% accuracy. The detector must be able to reject background events from decay channels of which the branching fractions are up to 10 orders of magnitude larger than the signal and with similar experimental signature. To totally suppress the main background from K+→μ+ν decay (BR ∼ 63%), NA62 will need a further μ rejection factor better than 5x10-3. This will be provided by a gas RICH detector for π/μ separation in a momentum range between 15 and 35 GeV/c. The details of the RICH project will be described and the results of two beam tests performed at CERN with prototypes will be presented.