Operating results from the DELPHI ring imaging Cherenkov (RICH)

Abstract

The DELPHI collaboration has designed and implemented a Cherenkov Ring Imaging Detector (RICH) which surrounds the interaction region of DELPHI at the LEP e+e− storage ring. The Barrel part of the RICH detector, which covers the 40°–140° polar angle, is fully operational since October 1991.The RICH detector measures the emission angle of Cherenkov light photons emitted by charged particles crossing first a 1 cm×22 m2 liquid radiator (C6F14) and next a 40 cm×32 m2 gas radiator (C5F12). The light is detected by a 5 cm×27 m2 photon converter which acts as a Time Projection Chamber. The conversion volume is filled with ethane‐methane mixture, with the addition of a small amount of vapor of a photosensitive substance (TMAE) that acts as the photon converter. It identifies charged particles with a momenta between 0.7 and 20 GeV.The analysis of the performance of the RICH is given using the Z0 events collected since October 1991. This performance is close to the values of the original design.