Year

2014

Degree Name

Doctor of Philosophy

Department

Centre for Medical Radiation Physics

Abstract

The introduction of the silicon photomultiplier (SiPM) has had a significant impact on the field of scintillator-based radiation detection. The SiPM provides photosensitivity and gain performance similar to that of traditional photomultiplier tubes, combined with the small size, low cost and ruggedness associated with solid-state technology. Alongside recent advances in organic scintillators and high-speed digital technologies, SiPMs offer the prospect of developing light-weight and reliable neutron detection technologies for novel industrial and security applications.

This thesis describes the development of radiation detectors using scintillators with SiPM readout and digital pulse processing (DPP); a particular focus being the use of pulse shape discrimination (PSD) to separately measure fast-neutrons and gammarays in mixed radiation fields. Digital algorithms were developed for the effective handling of the SiPM signals, with a genetic algorithm used to automatically optimise the filters used for pulse shape analysis. Efficient PSD was demonstrated down to electron-equivalent energies of 127 keV using a stilbene organic singlecrystal, and 391 keV using a novel EJ-299-34 plastic scintillator. The DPP techniques were implemented on an embedded digital signal processor (DSP), allowing detection and analysis to be carried out in real-time.

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