Test Beam Data Analysis and Simulation of a RICH Prototype for the NA62 Experiment

The NA62 experiment at CERN, aimed to measure K⁺ rarr pi⁺nunumacr branching fraction (O(10^-11)) , relies on a gas based RICH detector for pi/mu separation and level 0 trigger. The experiment requirements for this detector are mainly a time resolution better than 100 ps and a muon rejection better than 5 times 10^-3 in the momentum range 15-35 GeV/c. A first prototype of such a detector has been built and tested in 2007; it is a full length (18 m) Ne filled vessel equipped with a spherical mirror and 96 PMs on its focal plane, ap17 m upstream of the mirror. This prototype has been tested at CERN SPS on a 200 GeV/c pion beam mainly as a first check of its time resolution and of the light collection technique; the time resolution has been found to be about 65 ps, and the light collection, i.e. the number of hit PMs per ring, fairly as expected.