Cherenkov detectors in the ALICE experiment at LHC

The ALICE experiment is devoted to measure the properties of the strongly interacting matter created in heavy-ion collisions at LHC at S N N = 5.5 TeV . The ALICE-HMPID is a ring imaging Cherenkov detector with liquid C6F14 as radiator, dedicated to the identification of charged pions and kaons in the range 1 ≤ p ≤ 3 GeV/c and protons in the range 2 ≤ p ≤ 5 GeV/c . It consists of seven identical proximity focusing RICH counters, exploiting large area MWPC equipped with CsI photocathodes, for Cherenkov light imaging. Furthermore, results from experiments at RHIC and theoretical studies have shown that to understand the hadronization mechanisms in heavy-ion collisions is very important to identify track-by-track charged hadrons at larger momenta ( 10 − 30 GeV/c ). Therefore an upgrade of ALICE PID capability is advisable. A possible upgrade is under study and it consists of a ring imaging Cherenkov detector, called VHMPID. HMPID characteristics and results from cosmic and first beam data taking are described. Description of VHMPID and performance results from simulation are also reported