JINST Instrumentation Theses Archive

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:

• Charge induction
• Detector modelling and simulations II (electric fields, charge transport, multiplication and induction, pulse formation, electron emission, etc)
• Gaseous detectors
• 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.