Browsing by Author "Sarbutt, A"

Now showing 1 - 6 of 6
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    Charge transport properties of CdMnTe radiation detectors
    (EDP Sciences, 2012-04-11) Rafiei, R; Boardman, DA; Reinhard, MI; Sarbutt, A; Kim, KH; Watt, GC; Uxa, S; Prokopovich, DA; Belas, E; Bolotnikov, AE; James, RB
    Growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe) radiation detectors have been described. Alpha-particle spectroscopy measurements and time resolved current transient measurements have yielded an average charge collection efficiency approaching 100 %. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been associated with chains of tellurium inclusions within the detector bulk. Further, it has been shown that the role of tellurium inclusions in degrading charge collection is reduced with increasing values of bias voltage. The electron drift velocity was calculated from the rise time distribution of the preamplifier output pulses at each measured bias. From the dependence of drift velocity on applied electric field the electron mobility was found to be μn = (718 ± 55) cm2/Vs at room temperature. © 2012 the Authors, published by EDP Sciences.
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    Engineering silicon carbide for enhanced borders and ports security
    (Springer, 2019-09-17) Capan, I; Brodar, T; Pastuovic, Z; Bernat, R; Coutinho, J; Radulović, V; Snoj, L; Torres, V; Sarbutt, A; Ohshima, T.; Ereš, Z; Ambrožič, K; Yamazaki, Y; Makino, T
    Developing new state-of-the-art, low-cost and radiation hard detectors is an extremely difficult challenge which can be tackled only by a multisciplinary group of scientists and engineers from various fields having access to different infrastructure. In our project, Engineering silicon carbide for enhanced borders and ports security (-SiCure) funded by the NATO SPS programme [project number G5215] five partners from Australia (ANSTO), Croatia (RBI), Japan (QST), Portugal (UA) and Slovenia (JSI) have created a team whose main goal is to develop a SiC detector of special nuclear materials. © 2023 Springer Nature Switzerland AG
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    Evaluation of novel gamma ray imaging technology
    (Australasian Radiation Protection Society, 2017-08-09) Guenette, MC; Boardman, DA; Sarbutt, A; Flynn, A; Prokopovich, DA
    We present the imaging results from a novel single pixel gamma-ray imaging system, developed at ANSTO, which is capable of providing quantitative, spectroscopic gamma images using a fast and efficient imaging methodology. Gamma ray imaging can assist in surveying active areas by providing information of the radiation environment in areas which are hard to reach (e.g. in enclosed spaces or at height) and by gaining valuable information about the radiation environment whist limiting exposure to personnel in high dose rate environments. The system design provides a large field of view (360° × 70°) and covers a wide energy range of 40 keV to 1.5 MeV. The gamma ray image is overlaid on a 360° panoramic optical image of the scene, which allows for easy location of the gamma emitting radionuclides that are present. By selecting different regions of interest in the recorded gamma spectrum, separate radionuclide specific images, of the area being surveyed, can be visualised. Calibration of the detector allows for quantitative mapping of where each component of the dose rate at the detector originates. This can be converted into activity with a priori knowledge of the scene geometry. Gamma-ray images have been experimentally obtained for both point sources and extended sources in controlled testing environments and these results will be presented. The imaging results from a range of real world operational environments, around the ANSTO site, will be presented and demonstrate the systems capability for locating sources of radiation in nuclear industry applications.
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    High-purity CdMnTe radiation detectors: a high-resolution spectroscopic evaluation
    (Intistute of Electrical Engineers, 2013-02-07) Rafiei, R; Reinhard, MI; Kim, KH; Prokopovich, DA; Boardman, DA; Sarbutt, A; Watt, GC; Bolotnikov, AE; Bignell, LJ; James, RB
    The charge transport properties of a high-purity CdMnTe (CMT) crystal have been measured at room temperature down to a micron-scale resolution. The CMT crystal, doped with indium, was grown by the vertical Bridgman technique. To reduce the residual impurities in the Mn source material, the growth process incorporated a five-times purification process of MnTe by a zone-refining method with molten Te solvent. The resulting 2.6 mm thick crystal exhibited an electron mobility-lifetime product of μnτn=2.9 × 10-3 cm2V-1. The velocity of electron drift was calculated from the rise time distribution of the preamplifier's output pulses at each measured bias. The electron mobility was extracted from the electric field dependence of the drift velocity and at room temperature it has a value of μn=(950±90) cm2/Vs. High-resolution maps of the charge collection efficiency have been measured using a scanning microbeam of 5.5 MeV 4He2+ ions focused to a beam diameter <; 1 μm and display large-area spatial uniformity. The evolution of charge collection uniformity across the detector has been highlighted by acquiring measurements at applied biases ranging between 50 V and 1100 V. Charge transport inhomogeneity has been associated with the presence of bulk defects. It has been demonstrated that minimizing the content of impurities in the MnTe source material is highly effective in achieving major improvements in the CMT detector's performance as compared to previous data. © 2013, IEEE.
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    Primary standardisation of technetium-99m by liquid scintillation coincidence counting
    (Elsevier B. V., 2020-02) van Wyngaardt, WM; Tobin, SM; Lee, S; Smith, ML; Jackson, TW; Ilter, J; Howe, B; Sarbutt, A
    Technetium-99m was standardised by the 4π(LS)ce-γ coincidence extrapolation method. Sensitivity of the 4π(LS) channel to two types of radiation, namely conversion electrons and γ-rays, resulted in incorrect activity values being obtained when this was not adequately accounted for. Measurements were more robust when the LS detection efficiency was optimised, and when a γ-window setting was used that monitored the combined LS efficiency for conversion electrons and γ-rays. The primary standard was internationally compared through participation in the BIPM.RI(II)-K4.Tc99m key comparison. © 2019 Elsevier Ltd
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    Single pixel compressive gamma-ray imaging with randomly encoded masks
    (IOP Publishing, 2020-04-15) Boardman, DA; Sarbutt, A; Flynn, A; Guenette, MC
    We report on the development and demonstration of a single pixel spectroscopic gamma-ray imaging concept based on the principles of compressed sensing. Compressive gamma-ray images were obtained for both point sources and complex extended sources. The reconstruction of images at different photon energies allowed the spatial mapping of different radionuclides. When compared to traditional aperture based gamma-ray imaging techniques, the point source images were generated with ten times fewer measurements. More complex extended source images were generated with up to three times fewer measurements. Gamma-ray imaging techniques designed around the principles of compressed sensing have the potential to exploit the sparsity typically found in gamma-ray images, leading to a new class of fast and low cost imaging systems. © Copyright 2020 IOP Publishing