Performance of the High Momentum Particle IDentification detector of ALICE during the LHC run period 2015–2016

Abstract

In the period June 2015–September 2016 the LHC has delivered pp and Pb-Pb collisions respectively at √s=13TeV and √sNN=5.02TeV for a total integrated luminosity in ALICE of 14pb−1. The High Momentum Particle IDentification detector (HMPID) is part of the ALICE experiment. It is based on seven Ring Imaging Cherenkov (RICH) modules, 1.3×1.3m2 each, with a proximity focusing geometry. The Cherenkov photon detection is achieved by pad segmented photocathodes, coated with 300nm thick Caesium Iodide layer, installed in multiwire proportional chambers. Liquid C6F14 (perfluorohexane) with n=1.2989 at λ=175nm is used as Cherenkov radiator. The HMPID 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. The scatter plots of the Cherenkov angle for both pp and Pb-Pb events are presented as preliminary Particle Identification (PID) performance. After the good results shown during 2010–2013, in this paper the HMPID performance in the period 2015–2016, with emphasis on the CsI quantum efficiency stability, are presented. Finally the perspectives of the detector operation in the period HL-LHC 2019–2022, are briefly discussed.