Speaker
Description
The High Momentum Particle IDentification (HMPID) detector installed in the ALICE experiment on the LHC at CERN consists of seven Ring Imaging Cherenkov (RICH) modules, 1.3x1.3 m2 each, having proximity focusing geometry. The Cherenkov photon detection is achieved by means of pad segmented photocathodes coated with 300 nm thick Caesium Iodide layer and installed in multiwire proportional chambers operated with CH4. Liquid C6F14 (perfluorohexane) with n=1.2989 @ lambda=175nm is used as Cherenkov radiator. The HMPID identifies with three sigma separation charged pi and K in the momentum range 1-3 GeV/c, and protons in the range 1.5-5 GeV/c.
During 2015 (LHC Run2 period) and in the first half of 2016 LHC has delivered pp and Pb-Pb collisions respectively at 13 TeV √𝑠 and 5.02 TeV √𝑠𝑁𝑁 . After the good performance that HMPID has shown during Run1 (2010-2013), the study of the stability of the CsI photocathodes with respect to: the charge dose from ion bombardment, polluting gases, possible ageing effects ten years after the CsI evaporation and the C6F14 transparency, is presented. Some considerations on the future detector operation in the period 2019-2022 are also given.
Finally as overview of the detector performance, the scatter plots of the Cherenkov angle for both pp and Pb-Pb events are presented.
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