Aging effects in gas detectors

Degradation of performance of gas detectors under irradiation has been observed since the start of their use in particle physics experiments. In general, the observed damage depends on the amount of radiation seen by the detector but in addition many other parameters like gas composition, gas quality, particle rate and particle type play an extremely important role. The dramatically increased demands in terms of radiation hardness at experiments like HERA-B or those at the LHC have triggered intensive and systematic studies of aging properties of materials, gases and components, resulting in a compilation of a long list of materials which are unusable for high rate experiments, and a selection of materials with acceptable aging properties. Comparisons with results obtained in plasma chemistry have led to an improved understanding of aging phenomena, but due to the large complexity of the processes involved it has until now not been possible to derive recipes which can be generally applied to all high rate applications.