Oakley Clark


Postgraduate Research Student

About

My research project

Publications

Oakley Clark, Matt Wilson, Philip Evans, Emma Harris, Silvia Pani (2023)Corrections to Bremsstrahlung spectra for a hyperspectral x-ray detector, In: Lifeng Yu, Rebecca Fahrig, John M. Sabol (eds.), Progress in Biomedical Optics and Imaging - Proceedings of SPIE124631246328pp. 1246328-1-1246328-6 SPIE

A Monte-Carlo model was developed to simulate the response of a pixelated hyperspectral CZT X-ray detector. The first part of the simulation was carried out using Geant4, to obtain a list of energy depositions inside the CZT crystal. The second part of the simulation used charge transport equations to calculate the size of the electron charge cloud, as it drifts under the electric field to be read out. Experimentally acquired data from an Am-241 source with the HEXITEC detector were compared to simulated data, and good agreement was found. The model was used to investigate the energy dependence of fluorescence and charge sharing effects. Firstly, the probability of producing an escaped fluorescence photon was quantified as a function of primary photon energy. As expected, at primary photon energies just above the K-edge of Cd, there is a greater chance of producing an escaped fluorescence photon, and this probability decreases as the primary photon energy increases. Secondly, the probability of an event being shared across multiple pixels as a function of primary photon energy was quantified. It was found that as the primary photon energy is increased, there is a greater chance of producing an event shared across multiple pixels. The detector response to a Bremsstrahlung spectrum was simulated. Using previous results, fluorescence and charge sharing effects were corrected for, giving a corrected spectrum in good agreement with the input spectrum.

Oakley Clark, Matt Wilson, Philip Evans, Emma Harris, Silvia Pani (2023)Corrections for Fluorescence and Charge Sharing Effects to Bremsstrahlung Spectra for a Hyperspectral Pixelated CZT X-ray Detector, In: IEEE transactions on nuclear sciencepp. 1-1