Aging workshop provides a useful review of the long-term use of gaseous detectors

Detectors, like people, encounter problems as they get older. However, with foresight and experience, these problems can be minimized and even overcome. The recent international workshop on aging phenomena in gaseous detectors, which was held at DESY in Hamburg on 2-5 October, saw some 90 experts from 17 countries grappling with the dreaded “aging effects” that occur in gaseous particle detectors.

The workshop provided a long-overdue exchange of experiences concerning this specialized topic, which is of increasing importance in the high-rate era of today’s collider projects. The previous workshop on the subject had been held at Berkeley more than 15 years ago. Through 50 talks and posters the participants reviewed aging effects that can seriously impede the operation of gaseous detectors or even render them inoperable. Besides the well known, yet still poorly understood, aging due to gas polymerization, lesser-known anode swelling and etching effects in gas mixtures containing oxygen and fluorine compounds (CF₄, for example) were widely discussed. Presentations on gases and materials for detectors and gas systems stressed that very careful selection and testing of all system components are imperative to ensure the survival of detectors.

The long-term experience with large drift chamber operation in experiments at various colliding beam machines – HERA (DESY), LEP (CERN) and the Tevatron (Fermilab) – were reviewed as well as more recent high-rate results from HERA-B detectors and prototype detectors for LHC experiments at CERN. Aging in classical drift chambers and tubes, and in various forms of microstrip gas detectors, was discussed. Special sessions dealt with aging problems in photosensitive detectors and resistive plate chambers, in the BaBar and BELLE experiments at the new B-particle factories, for example.