Abstract
The ALICE High-Momentum Particle IDentification RICH detector is equipped with CsI photocathodes (PCs) in a MWPC for the detection of Cherenkov photons. The long-term operational experience with large-area CsI PCs is described. The RICH prototypes have shown a very high stability of operation and performance at a gain of 10 5 and with rates up to 2×10 4 cm −2 s −1. When exposure to air is avoided, no degradation of the CsI quantum efficiency has been observed on PCs periodically exposed to test beams over 7 years, corresponding to local integrated charge densities of ∼1 mC/cm 2. The results of limited exposures to oxygen and humidity are also presented.
Highlights
ALICE is the only LHC experiment dedicated to the heavy ion physics [1]; it will study p-p, p-A and A-A collisions at a center of mass energy s = 5.5 A TeV
The ALICE High Momentum Particle IDentification (HMPID) system is based on a RICH detector equipped with CsI photocathodes (PCs) for the detection of the Cherenkov light [2]
The main steps of the analysis are: a) definition of a fiducial area which includes all Cherenkov photons that reach the PC, depending on the detector geometry and the beam momentum; b) pad clusters analysis and deconvolution, to locate single photoelectron clusters and measure the chamber gain; c) evaluation of the main quantities: clusters multiplicity and size, total pad hits, ring radius spread, Cherenkov angle resolution; d) tuning of a CsI quantum efficiency (QE) curve by a Monte Carlo detector simulation, where all the processes, from the Cherenkov photons generation up to the signal induced on the pads, are taken into account
Summary
The ALICE High Momentum Particle IDentification (HMPID) system is based on a RICH detector equipped with CsI photocathodes (PCs) for the detection of the Cherenkov light [2]. Within the CERN project RD26, 32 CsI PCs, having area from 20x10 to 64x40 cm, have been produced in the period 1993-1997 [8] This project, aiming at the study of photosensitive CsI films for the detection of Cherenkov light, allowed the definition of a procedure to prepare large area CsI PCs with reproducible high QE. PC29 to PC32 have an area of 40x64 cm and were produced during June and July 1997 They are part of the larger proto-2, measuring 2/3 of a full HMPID module that is equipped with six PCs. At the end of 1999 proto-2 has been installed in the STAR experiment at BNL. Between any observed QE decrease and the possible contact with aging sources
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
