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NA62 is the last generation kaon experiment at CERN SPS aiming to study the decay K + → π + ν ν ¯ . The goal of the experiment is to measure the decay branching ratio, O ( 10 − 10 ) , with 10% precision collecting about 100 K + → π + ν ν ¯ events in three years of data taking and assuming a 10% signal acceptance. The weak signal and the huge background make the experiment very challenging. The NA62 detector must be able to reject background events from decay channels with branching ratios up to 10 orders of magnitude higher than the signal one and with similar experimental signature. In order to achieve the designed goal, good Particle Identification (PID), kinematic rejection and precise timing are required. The key element of the PID in NA62 is the Ring Imaging Cherenkov detector (RICH) to identify pions and muons and to measure the particle arrival time. After a pilot run in 2014, installation and commissioning of the detector were completed in 2015, when also the first physics run took place. Results on the detector performance will be presented together with preliminary results from the 2015 and 2016 physics runs. [ABSTRACT FROM AUTHOR]

Abstract: A Ring Imaging Cherenkov (RICH) detector is the key element for particle identification in the NA62 experiment at CERN. Its purposes are to distinguish pions from muons in the momentum range from 15GeV/c to 35GeV/c with a muon suppression factor at the 0.5% level, to measure the particle arrival time with better than 100ps resolution and to provide the reference time and a fast signal for the trigger system. This paper describes the updated detector design, the present status of the construction, the final results of a prototype beam test and a possible application of Graphics Processing Units in the NA62 trigger system based on RICH information. [Copyright &y& Elsevier]

Abstract: A RICH prototype has been constructed and tested. The detector was cylindrical, 17m long and 60cm diameter, filled with neon gas at atmospheric pressure. A spherical mirror with 17m focal length was used and 96 photomultipliers were placed in the mirror focal plane. The prototype was exposed to a momentum negative beam derived from the CERN SPS in the 2007 fall. The performances of the detector in terms of Cherenkov angle resolution, number of photoelectrons and time resolution are presented. [Copyright &y& Elsevier]

The Ring Imaging Cherenkov detector of the NA62 experiment at the CERN SPS is a key element of particle identification in the NA62 experimental strategy. The detector fulfills different conditions: to distinguish pions from muons with a muon rejection factor of O(10 2) in the NA62 momentum range of operation, between 15 and 35 GeV/c; to measure particle arrival time in the decay region with a precision better than 100 ps; to provide fast signals and reference time to the NA62 trigger system. The main design aspects and functional characteristics, as well as the performance of the detector measured with the data taken in the first NA62 physics runs, will be summarized in this paper. • The NA62 experiment aims to measure the branching ratio of the K + → π + ν ν ¯ decay. • The NA62 RICH performance fulfills the experiment requirements. • Pion–muon identification is performed with a muon rejection factor of O(102). • Time resolution with precision better than 100 ps is achieved. • The RICH is a key element to select charged particles in the trigger system. [ABSTRACT FROM AUTHOR]

The NA62 experiment aims to measure the B R (K + → π + ν ν ̄) with a 10% precision. One of the main backgrounds comes from the decay K + → μ + ν , therefore a highly powerful pion/muon separation is needed. The NA62 RICH, together with the calorimeter system, provides an accurate particle identification which has been essential to obtain the first results of the NA62 K + → π + ν ν ̄ analysis, based on 2016 data. Two different algorithms have been exploited which, used in combination, allowed to get a pion reconstruction and identification efficiency of 75%, with a muon suppression factor of about 500, in the momentum range 15–35 GeV/c. [ABSTRACT FROM AUTHOR]

The Ring Imaging Cherenkov detector of the NA62 experiment at CERN SPS was commissioned in 2014, but the optimal performance was achieved in 2016 after the precise mirror alignment with reconstructed tracks. The measurement and monitoring of basic performance parameters is discussed: ring radius resolution, ring centre resolution, single hit resolution and mean number of hits per ring. The performance is measured with 2016 data on the positron sample. Different contributions to the resolutions are calculated. [ABSTRACT FROM AUTHOR]