The RICH detector of the NA62 experiment at CERN

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 R({K + } to {mu + }nu ) 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 (pions against muons). The Ring Imaging Cherenkov detector (RICH) gives a muon rejection higher than a factor 100 in the momentum range 15-35 GeV/c, and measures the track crossing time with a resolution better than 100 ps. It is also exploited to provide trigger for charged particles. In this contribution the RICH detector will be described, together with its basic performance, the mirrors alignment procedure and its usage in {K + } to {pi + }nu bar nu search

Heavy neutrino searches and NA62 status

The NA62 experiment at CERN SPS recorded in 2007 a large sample of $K^+\to\mu^+\nu_\mu$ decays. A peak search in the missing mass spectrum of this decay is performed. In the absence of observed signal, the limits obtained on $\mathcal{B}(K^+\to\mu^+\nu_h)$ and on the mixing matrix element $|U_{\mu4}|^2$ are reported. The upgraded NA62 experiment started data taking in 2015, with the aim of measuring the branching fraction of the $K+\to\pi^+\nu\bar{\nu}$ decay. An update on the status of the experiment is presented.The NA62 experiment at CERN SPS recorded in 2007 a large sample of $K^+ \to \mu^+ \nu_{\mu}$ decays. A peak search in the missing mass spectrum of this decay is performed. In the absence of observed signal, the limits obtained on $\mathcal{B}(K^+ \to \mu^+ \nu_h)$ and on the mixing matrix element $\lvert U_{\mu 4} \rvert ^2$ are reported. The upgraded NA62 experiment started data taking in 2015, with the aim of measuring the branching fraction of the $K^+ \to \pi^+ \nu \bar{\nu}$ decay. An update on the status of the experiment is presented