Speaker
Ozkan Sahin
(Department of Physics Uludag University, Bursa, Turkey)
Description
Avalanche development in gas-based detectors relies not only on direct ionisation but also on excitation of noble gas atoms. Excited atoms can, in some gas mixtures, ionise the quencher molecules they collide with. We have reported on this process earlier. Alternatively, excited atoms can decay by photon emission. If these photons are insufficiently absorbed by the quencher, yet capable of ionising, then they may escape from the avalanche region and start secondary avalanches. This process, called photon feedback, leads to an over-exponential increase of the gas gain which limits the working range. In this paper, we derive photon feedback parameters from published gain measurements for several gas mixtures and fit these parameters in a model which describes their dependence on the quencher concentration and the pressure.
Primary author
Ozkan Sahin
(Department of Physics Uludag University, Bursa, Turkey)
Co-authors
Ilhan Tapan
(Department of Physics Uludag University, Bursa, Turkey)
Rob Veenhof
(RD51 collaboration, CERN, Gen‘eve, Switzerland)
