2006 JINST TH 005
Ph.D. degree thesis
accepted by University of Michigan, United States, in 2006
Scott Douglas Kiff
Supervisor: Zhong He
Coplanar Anode Implementation in Compressed Xenon Ionization Chambers
Keywords:
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Charge induction
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Detector modelling and simulations II (electric fields, charge transport, multiplication and
induction, pulse formation, electron emission, etc)
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Gaseous detectors
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Spectrometers
Abstract:
This dissertation examines the problem of microphonic degradation of high-pressure
xenon ionization chambers.
A detector design that utilizes coplanar anodes is
proposed to mitigate this problem, and an optimization study finds the best geometry given some
constraints on the system. A radial position-sensing method is developed from theory and
implemented in experiments, demonstrating usefulness in the areas of hardware diagnostics and
energy spectrum enhancement. Detailed simulations quantify the effects of various physical
processes on the measured energy spectrum; the processes that degrade the photopeak most severely
also show promise for improvement via design and operational changes. Simulations show
multiple-site events are undesirable due to resolution degradation.
A hydrogen cooling admixture is implemented to improve energy resolution after detailed
simulations predict advantageous performance changes. The detector linearity is shown to be quite
good over the range tested, 80-1330 keV. The best measured energy resolution is 4.2% FWHM at 662
keV, which is near the range that would be considered competitive with the less-rugged detectors
employing Frisch grids.
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