A fast neutron and dual-energy gamma-ray absorption method (NEUDEG) for investigating materials using a 252Cf source |
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| Institution: | 1. Contracted Lecturer, School of Chemical and Physical Sciences, Victoria University, PO Box 600, Wellington, New Zealand;2. Penguin Scientific and Medical Ltd., 15 Penguin Grove, Waitangirua, Porirua 5024, New Zealand;1. College of Environment and Chemical Engineering & State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387, PR China;2. College of Science, Tianjin University of Science & Technology, No. 29 Shisan Street, Kaifa District, Tianjin 300457, PR China;1. Department of Physics, University of Malaya, Kuala Lumpur, Malaysia;2. Centre for Biomedical Physics, School of Healthcare and Medical Sciences, Sunway University, 47500, Bandar Sunway, Selangor, Malaysia;3. Department of Physics, Kuwait University, Kuwait City, Kuwait;4. Department of Physics, University of Surrey, Guildford, Surrey, UK;1. Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan;2. Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan;1. Institute of Nuclear Research of the Hungarian Academy of Sciences, (ATOMKI), 4001 Debrecen, Pf. 51, Hungary;2. Institute of Experimental Physics, University Debrecen (IEP), 4010 Debrecen-10, Pf. 105, Hungary;1. Department of Physics, College of Education for Pure Science, Mosul University, Iraq;2. Department of Physics, College of Science, Mosul University, Iraq;3. Electronic Physics, Somy University, Ukraine |
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| Abstract: | DEXA (dual-energy X-ray absorption) is widely used in airport scanners, industrial scanners and bone densitometers. DEXA determines the properties of materials by measuring the absorption differences of X-rays from a bremsstrahlung tube source with and without filtering. Filtering creates a beam with a higher mean energy, which causes lower material absorption. The absorption difference between measurements (those with a filter subtracted from those without a filter) is a positive number that increases with the effective atomic number of the material. In this paper, the concept of using a filter to create a dual beam and an absorption difference in materials is applied to radiation from a 252Cf source, called NEUDEG (neutron and dual-energy gamma absorption). NEUDEG includes absorptions for fast neutrons as well as the dual photon beams and thus an incentive for developing the method is that, unlike DEXA, it is inherently sensitive to the hydrogen content of materials. In this paper, a model for the absorption difference and absorption sum in NEUDEG is presented using the combined gamma ray and fast neutron mass attenuation coefficients. Absorption differences can be either positive or negative in NEUDEG, increasing with increases in the effective atomic number and decreasing with increases in the hydrogen content. Sample sets of absorption difference curves are calculated for materials with typical gamma-ray and fast neutron mass attenuation coefficients. The model, which uses tabulated mass attenuated coefficients, agrees with experimental data for porcelain tiles and polyethylene sheets. The effects of “beam hardening” are also investigated. |
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| Keywords: | Neutrons Gamma rays Dual beams Filters Models Count rate Composition |
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