The RICH detector of the NA62 experiment

The RICH detector of the NA62 experiment is one of the key detectors to achieve the muon rejection needed in the search for the ${K}^{+}\to {\pi }^{+}\nu \bar{\nu }$ decay, performed by NA62. Since BR(K⁺ → µ⁺ν) is higher than BR(${K}^{+}\to {\pi }^{+}\nu \bar{\nu }$) by more than 9 orders of magnitude, it represents one of the most relevant background contributions. Its rejection is performed with kinematic reconstruction of the event and identification of the charged particles in the final state (π⁺ against µ⁺). The pion identification efficiency using the RICH detector is measured to be 83% in the momentum range between 15 and 35 GeV/c, with a misidentification probability for muons of 0.2%, while the track crossing time is measured with a resolution of 70 ps. The RICH detector is also exploited to provide trigger for charged particles with an efficiency greater than 99%.