The ALICE–HMPID performance during the LHC run period 2010–2013

Abstract

The ALICE–High Momentum Particle Identification Detector (HMPID) is based on seven modules of proximity focusing Ring Imaging Cherenkov detectors. It is equipped with CsI photo-cathodes for the Cherenkov photon detection installed in multiwire proportional chambers filled with methane. It uses liquid C6F14 as Cherenkov radiator and identifies with three sigma separation, charged π and K in the momentum range 1–3GeV/c, and protons in the range 1.5–5GeV/c.At the end of the first run period 2010–2013 of the Large Hadron Collider, the HMPID performance is analysed. No ageing effects of CsI photo-cathodes induced by the ion avalanches have been observed, and we do not expect to reach the charge threshold during the High Luminosity LHC run period 2019–2021.Leakages of C6F14 in 4 out of 21 quartz radiator vessels, combined with 3 HV failing sectors out of 42, have limited the full detector acceptance to 72%. Improvements on the filling operation of the vessels should minimize further leakage. Finally, the particle identification performances are introduced using p-Pb collisions. For Pb–Pb central collisions, where purity and contamination of identified particles are extracted via a Monte Carlo simulation, the impact of the background on the pattern recognition algorithm is briefly discussed.