Gamma-ray modulation properties of tungsten coded apertures for a novel mixed-field imaging system

Cieślak, M.J., Gamage, K.A.A. , Glover, R. and Taylor, C.J. (2019) Gamma-ray modulation properties of tungsten coded apertures for a novel mixed-field imaging system. Journal of Instrumentation, 14, P02007. (doi: 10.1088/1748-0221/14/02/P02007)

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An investigation into the gamma-ray modulation properties of a tungsten coded aperture, whose design is based on the mathematical principles of Modified Uniformly Redundant Arrays (MURA), has been performed. Due to the small size of the individual cells, the aperture was built using additive manufacturing methods. The gamma-ray field was produced by a 137Cs radioactive isotope at Lancaster University, U.K. An organic plastic scintillator sample, which is capable of pulse shape discrimination, has been used to detect the gamma-ray field modulated by a tungsten aperture. Prior to the investigation of the aperture modulation properties, energy calibration of the scintillator was performed. Its pulse shape discrimination capabilities were verified using a 252Cf fission source. In this study, each of 169 coded aperture cells was investigated by collimating the modulated gamma-ray field of 137Cs through a 25.4 mm thick lead supporting plate. The supporting plate has one opening in the centre, of the same dimensions as the single aperture cell, i.e. 2.5 mm×2.5 mm. The number of pulses detected for every aperture location were recorded in an array. The array was subsequently used to create a two-dimensional image of the source, which was encoded through the coded aperture pattern. Finally, the image was decoded using deconvolution techniques to reveal the actual source location. The new results obtained in this study indicate that sufficient gamma-ray modulation properties of the aperture can be determined, despite the relatively small footprint and thickness of the coded aperture.

Item Type:Articles
Additional Information:The authors would like to acknowledge the funding support from EPSRC (EP/M507891/1 and EP/R02572X/1), the Faculty of Science and Technology (Lancaster University, U.K.) and Sellafield Ltd.
Glasgow Author(s) Enlighten ID:Gamage, Professor Kelum
Authors: Cieślak, M.J., Gamage, K.A.A., Glover, R., and Taylor, C.J.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:Journal of Instrumentation
Publisher:Institute of Physics Publishing Ltd.
ISSN (Online):1748-0221
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Journal of Instrumentation
Publisher Policy:Reproduced under a Creative Commons License

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