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INDIA: Photon multiplicity detector

Abstract

Full text: The team of Indian scientists from Calcutta's Variable Energy Cyclotron Centre, Bhubaneswar Institute of Physics, Panjab (Chandigarh), Rajasthan (Jaipur) and Jammu in collaboration with GSI Darmstadt have contributed a large and highly granular preshower photon multiplicity detector (PMD) for the WA98 experiment at the CERN SPS proton synchrotron. This experiment studies high energy collisions of lead ions and will measure both charged particle and photon multiplicity in a large overlap region. The motivation for measuring photon multiplicity in ultra-relativistic heavy ion collisions stems from theoretical predictions of changes in the relative production of photons and charged particles in the phase transition of hadronic matter to quarkgluon plasma and its subsequent hadronization. The photon multiplicity detector consists of a matrix of scintillator pads placed in light-tight boxes and mounted behind the lead converter plates. The light from the scintillator pads is transported to the readout system using wavelength shifting (WLS) fibres. Developing on the team's earlier experience with a smaller version for the WA93 experiment (September 1991, page 16), several modifications were incorporated to improve light collection and transport. Use of improved WLS fibres, short WLS pieces to minimize self-absorption, and thermal splicing with long clear fibres were some  More>>
Authors:
Publication Date:
Jan 15, 1995
Product Type:
Journal Article
Report Number:
INIS-XC-16A0152
Resource Relation:
Journal Name: CERN Courier; Journal Volume: 35; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; CALCUTTA CYCLOTRON; CERN SPS SYNCHROTRON; ION BEAMS; LEAD IONS; READOUT SYSTEMS; SHOWER COUNTERS
OSTI ID:
22556006
Country of Origin:
CERN
Language:
English
Other Identifying Numbers:
Journal ID: ISSN 0304-288X; CODEN: CECOA2; TRN: XC16A0152127165
Availability:
Available on-line: http://cds.cern.ch/record/1732366/files/vol35-issue1-p014-e.pdf
Submitting Site:
INIS
Size:
page(s) 14-15
Announcement Date:
Jan 07, 2017

Citation Formats

Anon. INDIA: Photon multiplicity detector. CERN: N. p., 1995. Web.
Anon. INDIA: Photon multiplicity detector. CERN.
Anon. 1995. "INDIA: Photon multiplicity detector." CERN.
@misc{etde_22556006,
title = {INDIA: Photon multiplicity detector}
author = {Anon.}
abstractNote = {Full text: The team of Indian scientists from Calcutta's Variable Energy Cyclotron Centre, Bhubaneswar Institute of Physics, Panjab (Chandigarh), Rajasthan (Jaipur) and Jammu in collaboration with GSI Darmstadt have contributed a large and highly granular preshower photon multiplicity detector (PMD) for the WA98 experiment at the CERN SPS proton synchrotron. This experiment studies high energy collisions of lead ions and will measure both charged particle and photon multiplicity in a large overlap region. The motivation for measuring photon multiplicity in ultra-relativistic heavy ion collisions stems from theoretical predictions of changes in the relative production of photons and charged particles in the phase transition of hadronic matter to quarkgluon plasma and its subsequent hadronization. The photon multiplicity detector consists of a matrix of scintillator pads placed in light-tight boxes and mounted behind the lead converter plates. The light from the scintillator pads is transported to the readout system using wavelength shifting (WLS) fibres. Developing on the team's earlier experience with a smaller version for the WA93 experiment (September 1991, page 16), several modifications were incorporated to improve light collection and transport. Use of improved WLS fibres, short WLS pieces to minimize self-absorption, and thermal splicing with long clear fibres were some of the important changes incorporated. Tests showed signficantly improved light collection. The scintillator pads were fabricated at all the five collaborating centres in India and the complicated assembly in the detector box modules carried out at the Variable Energy Cyclotron Centre, Calcutta. More than 400 lead converter plates were machined in Calcutta to rigorous tolerances of 0.2 mm. The assembled detector box modules and lead plates were shipped to CERN in spring 1994 for tests and installation. The WA98 PMD consists of over 50,000 scintillator pads of sizes varying from 15 to 25 mm square and are assembled in 26 light-tight box modules. Each fibre matrix of 38 rows and 50 columns is read out using an image intensifier and CCD camera system. At present the PMD uses 26 readout cameras from the old UA2 experiment, including 20 units on loan from CERN. The detector covers an area of 21 square metres in the forward region. Its total weight with the stand and lead converter plates is about 6 tons. A central hole about 1 metre square avoids problems with overlapping showers. The detector took its first data during the lead ion run late last year (December 1994, page 15)}
journal = {CERN Courier}
issue = {1}
volume = {35}
journal type = {AC}
place = {CERN}
year = {1995}
month = {Jan}
}