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Proceedings Paper

Test apparatus to monitor time-domain signals from semiconductor-detector pixel arrays
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Paper Abstract

Pixellated semiconductor detectors, such as CdZnTe, CdTe, or TlBr, are used for gamma-ray imaging in medicine and astronomy. Data analysis for these detectors typically estimates the position (x, y, z) and energy (E) of each interacting gamma ray from a set of detector signals {Si} corresponding to completed charge transport on the hit pixel and any of its neighbors that take part in charge sharing, plus the cathode. However, it is clear from an analysis of signal induction, that there are transient signal on all pixel electrodes during the charge transport and, when there is charge trapping, small negative residual signals on all electrodes. If we wish to optimally obtain the event parameters, we should take all these signals into account. We wish to estimate x,y,z and E from the set of all electrode signals, {Si(t)}, including time dependence, using maximum-likelihood techniques[1]. To do this, we need to determine the probability of the electrode signals, given the event parameters {x, y, z, E}, i.e. Pr( {Si(t)} | {x, y, z, E} ). Thus we need to map the detector response of all pixels, {Si(t)}, for a large number of events with known x,y,z and E.In this paper we demonstrate the existence of the transient signals and residual signals and determine their magnitudes. They are typically 50-100 times smaller than the hit-pixel signals. We then describe development of an apparatus to measure the response of a 16-pixel semiconductor detector and show some preliminary results. We also discuss techniques for measuring the event parameters for individual gamma-ray interactions, a requirement for determining Pr( {Si(t)} | {x, y, z, E}).

Paper Details

Date Published: 23 September 2011
PDF: 10 pages
Proc. SPIE 8143, Medical Applications of Radiation Detectors, 81430P (23 September 2011); doi: 10.1117/12.898365
Show Author Affiliations
Kyle Haston, The Univ. of Arizona (United States)
H. Bradford Barber, The Univ. of Arizona (United States)
Lars R. Furenlid, The Univ. of Arizona (United States)
Esen Salçin, The Univ. of Arizona (United States)
Vaibhav Bora, The Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 8143:
Medical Applications of Radiation Detectors
H. Bradford Barber; Hans Roehrig; Douglas J. Wagenaar, Editor(s)

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