Title :
R&D on RPC for the muon trigger system for the ALICE experiment in view of p-p data taking
Author :
Arnaldi, R. ; Baldit, A. ; Barret, V. ; Bastid, N. ; Blanchard, G. ; Chiavassa, E. ; Cortese, P. ; Crochet, P. ; Dellacasa, G. ; Devaux, A. ; De Marco, N. ; Dupieux, P. ; Ferretti, A. ; Forestier, B. ; Gallio, M. ; Gemme, R. ; Grygorian, S. ; Guerin, F. ;
Author_Institution :
Dipt. di Fisica, Torino Univ., Italy
Abstract :
ALICE (a large ion collider experiment) is the heavy-ion dedicated experiment at LHC. The resistive plate chamber detector (RPC) with low-resistivity bakelite electrodes was selected for the trigger system of the muon spectrometer. Although the main goal of ALICE is the study of nucleus-nucleus collisions, reference data in p-p interactions will be collected as well. If, on one hand, RPC operation in streamer mode is adequate for data taking with ion beams, on the other hand, the more severe ageing requirements for p-p data taking lead us to explore the possibility of operating the detector in "highly-saturated avalanche" regime. A detailed study of the signal was carried out with cosmic rays to get a more precise view of the intrinsic properties of the gas mixture (among others the streamer fraction vs. HV). The possibility of detecting avalanche signals with our FEE designed for the streamer mode was successfully investigated. Furthermore, tests with muon beam at CERN were carried out with satisfactory results in terms of efficiency, time resolution and cluster size. An analysis of the exhaust gas showed a low HF content: this is an encouraging result in view of long term stability of the detector which is at present under test.
Keywords :
electrodes; ionisation chambers; muon detection; particle spectrometers; position sensitive particle detectors; 1H(p,X); ALICE experiment; LHC; ageing requirements; avalanche signal detection; cluster size; cosmic rays; exhaust gas analysis; front end electronics; highly-saturated avalanche regime; intrinsic gas mixture properties; large ion collider; long term stability; low high-frequency content; low-resistivity bakelite electrodes; muon spectrometer trigger system; nucleus+nucleus collisions; resistive plate chamber detector; streamer fraction; streamer mode RPC operation; time resolution; Aging; Cosmic rays; Detectors; Electrodes; Ion beams; Large Hadron Collider; Mesons; Research and development; Spectroscopy; Testing;
Conference_Titel :
Nuclear Science Symposium Conference Record, 2004 IEEE
Print_ISBN :
0-7803-8700-7
Electronic_ISBN :
1082-3654
DOI :
10.1109/NSSMIC.2004.1462431