Development of a Scintillator Based Coded-aperture Mixed-field Imaging System for Nuclear Decommissioning Applications

Gamage, K. A.A. (2018) Development of a Scintillator Based Coded-aperture Mixed-field Imaging System for Nuclear Decommissioning Applications. 2nd International Conference on Nuclear Power Plants: Structures, Risk & Decommissioning, London, UK, 10-11 Jun 2018.

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Coded-aperture imaging has been wieldy used in X-ray and gamma-ray detection and localisation systems. The same approach has also been successfully employed in large scale neutron imagers, where single channel detectors act as individual cells. Moreover, utilisation of organic scintillators allowed dual particle (neutron and gamma) detection, based on pulse shape discrimination (PSD) techniques. However, large scale systems can be difficult to deploy on nuclear decommissioning sites, where nuclear waste streams are often located in areas that are technically difficult to access. In this paper, we present the development of a small scale, easily deployable mixed-field coded-aperture imaging system. Due to hazardous nature of the target environment and susceptibility to leaks of organic liquid scintillators, only solid materials (organic plastics and stilbene crystal) have been considered as sensitive detectors in this work. Following the characterisation of the detectors a pixelated organic plastic scintillator (EJ-299-34) has been designed and computationally tested using Monte-Carlo methods (MCNPX). Subsequently, the pixelated scintillator was built, where scintillator pixels and anodes of the position-sensitive photomultiplier tube (PSPMT) match in size. Initial results of the pixelated scintillator (coupled with Hamamatsu 9500 PSPMT) characterisation suggest that not only the localised response, but also particle discrimination between neutrons and gamma-ray photons be possible. This information is obtained from the PSPMT generated pulses through a resistive network based readout electronics system linked to a bespoke, FPGA based, two-channel digitiser.

Item Type:Conference or Workshop Item
Glasgow Author(s) Enlighten ID:Gamage, Professor Kelum
Authors: Gamage, K. A.A.
College/School:College of Science and Engineering > School of Engineering

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