Pulse Temporal Splitting in Photon Counting X-Ray Detectors

We performed Monte-Carlo simulations of X-ray interactions and charge transport within a photon counting cadmium zinc telluride (CZT) detector. We study various physical processes affecting the width and shape of detected pulses and find that the energy resolution depends on the pulse width variance...

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Bibliographic Details
Published in:IEEE transactions on nuclear science 2012-08, Vol.59 (4), p.1480-1490
Main Authors: Engel, Klaus Jürgen, Steadman, Roger, Herrmann, Christoph
Format: Article
Language:English
Subjects:
Absorption
Attenuation
CdTe
Charge
Charge carrier processes
Clouds
Counting
counting circuits
CZT
Detectors
energy resolution
gamma ray detectors
Materials
Photonics
Photons
pulse height spectra
pulse width
Scattering
semiconductor radiation detectors
spectral response
Splitting
Temporal logic
X-rays
Zinc telluride
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Summary:We performed Monte-Carlo simulations of X-ray interactions and charge transport within a photon counting cadmium zinc telluride (CZT) detector. We study various physical processes affecting the width and shape of detected pulses and find that the energy resolution depends on the pulse width variance. One impact factor (and main topic of this work) is the temporal splitting of pulses due to the simultaneous creation of two or more charge clouds by K-fluorescence within the same pixel. Measured energies are underestimated if the timing constants of detector and electronics are below or in the order of the arrival time differences of the charge clouds. Pulse temporal splitting is of minor relevance if other effects like charge sharing or polarization by hole trapping are present which cause a stronger degradation of the pulse height spectrum.
ISSN:0018-9499
1558-1578
DOI:10.1109/TNS.2012.2203610