Doctor of Philosophy
Centre for Medical Radiation Physics
Preston, Rhys Mitchell, Neutron detection using scintillators with silicon photomultiplier readout and digital pulse processing, Doctor of Philosophy thesis, Centre for Medical Radiation Physics, University of Wollongong, 2014. http://ro.uow.edu.au/theses/4230
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.