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| Paper |
Radiation Safety Management Vol.1, No.1 (7-11) |
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| Specification of Radiation Field Generated by a Gamma-ray Source |
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Keiji Oda1), Nobumasa Miyawaki1), Tomoya Yamauchi1) and Suiki Baba2)
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1) Department of Nuclear Engineering, Kobe University of Mercantile Marine
2) Information Systems Equipment Division, Matsushita Industrial Equipment Co., Ltd
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Received April 22, 2002; accepted September 20, 2002
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| In this report are discussed the characteristics of a radiation field generated by a small gamma-ray source and the depth-dose curve in a material placed there. The experiments with TLDs and a 137Cs source resulted in a depth-dependence of about 30% decrease by aluminum wall of 100 mg/cm2, to the contrary of a well-known pattern, i.e. saturation after a rapid build-up for parallel photon beam. In order to investigate the discrepancy, a Monte Carlo simulation was employed to calculate the energy distribution of the secondary electrons in an approximate geometry of a spherical source of glass sealed in a stainless-steel capsule. It was confirmed that the surface dose may be affected considerably by secondary electrons generated in the capsule and/or the air between the source and the detector. The angular distribution of secondary electrons and scattered photons have also been calculated, with which the function of a collimator was discussed. |
| Key words: |
gamma-ray source, depth-dose curve, secondary electron, collimator |
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