Micromegas as a large microstrip detector for the COMPASS experiment

Citation
D. Thers et al., Micromegas as a large microstrip detector for the COMPASS experiment, NUCL INST A, 469(2), 2001, pp. 133-146
Citations number
8
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences","Instrumentation & Measurement
Journal title
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
ISSN journal
0168-9002 → ACNP
Volume
469
Issue
2
Year of publication
2001
Pages
133 - 146
Database
ISI
SICI code
0168-9002(20010811)469:2<133:MAALMD>2.0.ZU;2-X
Abstract
Recent results on the gaseous microstrip detector Micromegas which will be used to track particles in the COMPASS experiment at CERN are presented. De velopments concerning its mechanical and electrical design, associated read out electronics and gas mixture were carried out. Particular attention was paid to the discharge phenomenon which affects this type of microstrip dete ctor. The adequacy of the options finally retained, especially the SFE16 re adout and the use of a Ne-C2H6-CF4 gas mixture, was demonstrated in a set o f beam tests performed on a 26 x 36 cm(2) prototype. Operating at a gain of similar to 6400, full efficiency is reached along with a spatial resolutio n of similar to 50 mum and a timing accuracy of 8.5 ns. Discharges are kept at a low rate, less than one per SPS spill in a COMPASS-like environment. Via a decoupling of the strips through individual capacitors their impact i s greatly reduced. They generate a dead time on the full detector of simila r to 3 ms, affecting marginally the detection efficiency given their rate. The probability of discharge, at a given value of efficiency, is found to d ecrease with the mean value of the gas mixture atomic number. In view of th ese results, the commissioning of Micromegas for COMPASS is foreseen in the near future. (C) 2001 Elsevier Science B.V. All rights reserved.