Estimation of Fano factor in inorganic scintillators

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• 作者：Vaibhav Bora^a ; ^{bora.vaibhav@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Harrison H. Barrett^a ; ^{barrett@radiology.arizona.edu" class="auth_mail" title="E-mail the corresponding author} ; David Fastje^a ; ^{dfastje@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Eric Clarkson^a ; ^{clarkson@radiology.arizona.edu" class="auth_mail" title="E-mail the corresponding author} ; Lars Furenlid^a ; ^{furen@radiology.arizona.edu" class="auth_mail" title="E-mail the corresponding author} ; Abdelkader Bousselham^b ; ^{abousselham@qf.org.qa" class="auth_mail" title="E-mail the corresponding author} ; Kanai S. Shah^c ; ^{kanaishah@yahoo.com" class="auth_mail" title="E-mail the corresponding author} ; Jarek Glodo^c ; ^{jglodo@rmdinc.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Fano factor ; Inorganic scintillators ; Renewal point process ; Photon statistics
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2016
• 出版时间：1 January 2016
• 年：2016
• 卷：805
• 期：Complete
• 页码：72-86
• 全文大小：3213 K

文摘

The Fano factor of an integer-valued random variable is defined as the ratio of its variance to its mean. Correlation between the outputs of two photomultiplier tubes on opposite faces of a scintillation crystal was used to estimate the Fano factor of photoelectrons and scintillation photons.

Correlations between the integrals of the detector outputs were used to estimate the photoelectron and photon Fano factor for YAP:Ce, SrI₂:Eu and CsI:Na scintillator crystals. At 662 keV, SrI₂:Eu was found to be sub-Poisson, while CsI:Na and YAP:Ce were found to be super-Poisson.

An experiment setup inspired from the Hanbury Brown and Twiss experiment was used to measure the correlations as a function of time between the outputs of two photomultiplier tubes looking at the same scintillation event. A model of the scintillation and the detection processes was used to generate simulated detector outputs as a function of time for different values of Fano factor. The simulated outputs from the model for different Fano factors was compared to the experimentally measured detector outputs to estimate the Fano factor of the scintillation photons for YAP:Ce, LaBr₃:Ce scintillator crystals. At 662 keV, LaBr₃:Ce was found to be sub-Poisson, while YAP:Ce was found to be close to Poisson.