A progress report on the development of the CsI-RICH detector for the ALICE experiment at LHC

Abstract

The particle identification in A Large Ion Collider Experiment (ALICE) at LHC will be achieved by two complementary systems based on time-of-flight measurement, at low pt, and on the Ring Imaging Cherenkov (RICH) technique, at pt ranging from 2 to 5GeV/c, respectively. The High Momentum PID (HMPID) system will cover ∼5% of the phase space, the single-arm detector array being composed by seven 1.3×1.3m2 CsI-RICH modules placed at 4.7m from the interaction point where a density of about 50particles/m2 is expected.A 1m2 prototype, 23 of HMPID module size, has been successfully tested at the CERN/PS beam where 18 photoelectrons per event have been obtained with 3GeV/c pions and 10mm liquid C6F14 radiator. Mechanical problems related to the liquid radiator vessel construction have been solved and the prototype, fully equipped, will be tested at the CERN/SPS to investigate the PID capability in high particle density events.In this report, after an introductory discussion on the requirements for PID in ALICE, the HMPID prototype is described and the main results of beam tests on large area CsI photocathodes, operated in RICH detectors, are given.