PID performance of the High Momentum Particle IDentification (HMPID) detector during LHC-Run 2

The ALICE apparatus is devoted collecting proton–proton (pp), proton–nucleus (p–A) and nucleus–nucleus (A–A) collision data provided by the LHC, to study the properties of strongly interacting matter under extremely high temperature and energy density conditions. In ALICE, the momentum of a track is evaluated by exploiting a solenoid magnetic field of 0.5 T. Among the ALICE PID detectors, the HMPID (High Momentum Particle Identification Detector) is devoted to the identification of charged hadrons. It consists of seven identical RICH (Ring Imaging Cherenkov) counters, with liquid C $_6$ F$_{14}$ as Cherenkov radiator (n ≈ 1.298 at λ$_{ph}$ = 175 nm). Cherenkov photons and charged particles are detected by a MWPC (Multi Wire Proportional Chamber), equipped with a pad-segmented CsI coated photo-cathode. The HMPID provides 3 σ K– π and p–K separation up to p$_T$ = 3 and 5 GeV/ c , respectively. The detector performance depends on the experimental conditions, such as the event multiplicity and the intensity of the solenoid magnetic field. During the LHC Run 2 data-taking period (2015–2017), the HMPID collected data from different colliding systems with a magnetic field intensity B = 0.5 T and pp data with B = 0.2 T were also recorded. A review of the detector PID performance during the LHC Run 2 data-taking period will be shown. The contribution provided, so far, by the HMPID to the ALICE physics measurements, performed with the LHC Run 2 data, will also be presented.