Ageing effects observed in the CERN Omega RICH

doi:10.1016/0168-9002(94)90560-6

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Volume 343, Issue 1, 1 April 1994, Pages 258-262

https://doi.org/10.1016/0168-9002(94)90560-6 Get rights and content

Abstract

We report on the new drift chambers of the Omega RICH used in the hyperon beam experiment WA89 at the CERN-SPS and in the heavy-ion experiment WA94. After four data-taking runs in 1990/91/92 it was found that the anode wires of the chambers were coated with a smooth layer of 1 μm thickness. Pulse heights were found to be reduced considerably with respect to those observed on new wires. Washing with alcohol and water in an ultrasonic bath restored the original pulse heights. In 1993 the RICH is running again in experiment WA89.

References (2)

W. Beusch
Nucl. Instr. and Meth. A
(1992)
H.-W. Siebert

Cited by (9)

Cherenkov light imaging fundamentals and recent developments
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Citation Excerpt :
Examples include an upgraded Omega RICH [18] used by WA89 [20] and WA94 [21], DELPHI [22], SLD-CRID [23,24], CERES [25,26], and SPHINX [27]. These detectors reached about half of the originally expected number of detected photons, but all the losses could be eventually accounted for by carefully determining all the operational parameters; one large problem was the TMAE quantum efficiency and electron attachment length depending on the cleaning procedure of the TMAE [28,29]. These detectors still presented some operational challenges, but generally contributed to the physics output of the experiments.
Test-beam aging studies of a TMAE prototype for the HERA-B RICH
2003, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
The aging properties of a wire chamber, operating in a methane/TMAE gas mixture, were studied in a beam test. We emphasize here the precautions taken to minimize aging due to materials used in the chamber, and the redundancy in the design of the test. We compare our aging results to those recorded in the literature and find good agreement in the overall aging properties as a function of dose. We also report the results of increasing the high voltage of the aged chamber to restore the gain.
Aging measurements of a TMAE-based photon detector for the HERA-B RICH: Representing the HERA-B RICH collaboration
1999, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
We report on aging measurements of a photon detector candidate for the HERA-B RICH. The prototype, a proportional wire chamber operated with TMAE, was mounted on an argon filled test-beam RICH and was aged by UV light at rates we expect in HERA-B. We monitored gain and current continuously, and checked the chamber with Cherenkov photons at regular intervals. The number of detected photons/track (projected to 2.75 m C₄F₁₀ in HERA-B) dropped from 26 to 11 after two days of aging – well below the 20 required for π/K separation. Based on these results, HERA-B decided to use multi-anode PMTs as photon detectors in the RICH.
Aging measurements of a TMAE based photon detector for the HERA-B RICH
1998, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
We report on aging measurements of a photon detector candidate, based on proportional wire chambers operating in TMAE, for the HERA-B RICH. The detector consisted of 64 cells, each 100 mm long and 8×8 mm² in area, constructed with brass cathode and 45 μm gold plated tungsten anode wire and was operated at room temperature with 50% TMAE saturated methane. To age the chamber it was exposed for several weeks to UV light from a deuterium lamp at 3 MHz/cm² counting rate, the expected maximum rate in the HERA-B RICH. The detection efficiency of the chamber for Cherenkov photons, generated in 5 m of argon by a 3 GeV electron testbeam at DESY, was recorded at regular intervals during the aging process. The pulse-height distribution of the chamber was continuously monitored. We found significant chamber gain loss after an exposure equivalent to about one month of running at HERA-B. Based on our results HERA-B decided to employ a multi-anode PMT system as photon detector in the RICH.
Photon detectors with gaseous amplification
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^☆: Work supported by the Bundesministerium für Forschung und Technologie (codes 05 5HD15I, 06 HD524I, 06 MZ5265 TP2).

¹: Now at Fermi National Accelerator Laboratory, Batavia, IL, USA.

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Ageing effects observed in the CERN Omega RICH☆

Abstract

Nucl. Instr. and Meth. A