The RICH detector is required to improve the rejection of background from K+->μ+v decays providing positive identification of the Muon in the background events and an identification of the Pion in the signal events.
The RICH Detector is:
- Separating π+ from μ+ between 15 and 35 GeV/c momentum providing a muon suppression factor of at least 10-2
- Measuring the pion crossing time with a resolution of about 100 ps;
- Producing the L0 trigger for a charged track.
The RICH is situated between the last Straw Station (210m from the target) and the last Large Angle Veto station. It consists of a cylindrical vessel (Length ~18m, Ø=3.2 – 3.8m ) with the beam pipe passing in its center. The vessel is filled with Neon (1 atm), at the downstream end a mosaic hexagonal mirrors focuses the Cherenkov light onto 2x1000 photo detectors situated at the upstream end of the vessel.