Stability of the ALICE-HMPID detector in LHC runs 1 and 2 and PID performance in p-Pb collections at energy per nucleon pair of 8.02 TeV

Abstract

The stability over Runs 1 and 2 and the particle identification (PID) performance in p-Pb collisions at √snn= 8.02 Tev of the High Momentum Particle Identification Detector (HMPID), present in the A Large Ion Collider Experiment (ALICE) at the Large Hadron Collider (LHC) at CERN, were studied. The stability studies involved the analysis of pp collisions, the data of which was obtained in 2018. The analysis updated the already existing studies for Runs 1 and 2. Moreover, an additional study of the ageing of the Csl films of the photocathodes was done. The results obtained, shmv that the detector is stable over the two Run periods. The same cannot be said for Run2, which presents a general decrease in number of photons being detected, particularly for the RICH2 module, where the decrease is extensive. Thus, a more in-depth study of the Run and of the module were performed. On the other hand, the PID performance study involved the analysis of data obtained in pPb collisions at √snn= 8.02 Tev, which data was collected in 2016. This research also involved the stability of the detector during this data taking. Finally, the normalised raw yields of pions, kaons and ( anti-)protons were obtained for different multiplicities in the laboratory rapidity range -0.465 < Ylab < 0.035 for the p-Pb collisions at √snn= 8.02 Tev. The results obtained show that the PID performance of the detector is optimal and that the transverse momentum spectra of the particles present heavy-ion collision like behaviour.