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| Uncertainty Analysis for Determination of Air Kerma in γ-ray Beam |
| LI De-hong1,CHENG Jian-bo1,2,WANG Pei-wei1,LI Xing-dong1,GUO Bin1 |
1. National Institute of Metrology, Beijing 100029, China
2. Lanzhou University, Lanzhou, Gansu 73000, China |
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Abstract Based on the Bragg-Gray cavity theory of measurements of air kerma for gamma ray, the air kerma rate is measured by using graphite cavity ionization chamber, and the mathematical model of measurement is established. The effect of influence quantities and its correction are taken into account during the process of uncertainty analysis for the measurement of air kerma. The correction factors and its uncertainty are gotten by using the methods of measurement and Monte Carlo simulation. The expanded uncertainty of gamma ray air kerma is about 0.5%, and that the mainly contribution of the uncertainty of gamma ray air kerma are come from the uncertainty of wall correction and average ionization power, so it is necessary to carry out the corresponding research, in order to improve the uncertainty level of the air kerma rate measurement.
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Received: 27 November 2014
Published: 31 May 2016
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| ［1］Burns D T. A new approach to the determination of air kerma using primary-standard cavity ionization chambers ［J］. Phys Med Biol, 2006, 51(4): 929-942.
［2］Boutillon M, Niate M T. A Study of a Graphite Cavity Chamber for Absolute Exposure Measurements of 60Co Gamma Rays［J］. Metrologia, 1973,9(1):139-146.
［3］CCRI.The value of W/e and its uncertainty［C］// 16th meeting of the CCRI, Paris, France,1999.
［4］BIPM. Consultative Committee for Ionizing Radiation (CCEMRI) (Section I) ［R］. R15（2）,1972.
［5］JJF 1059.1—2012, 测量不确定度评定与表示［S］.
［6］CCRI. Corrections to air kerma standards［C］// 18th meeting of the CCRI, Paris, France,2003..
［7］Boutillon M. Volume recombination parameter in ionization chambers ［J］. Phys Med Biol, 1998,43(8): 2061–2072.
［8］Witzani J. Monte Carlo calculation of the wall correction factors for the air kerma standards of the BEV for 137Cs and 60Co γ-rays［R］. CCRI(I)/03-11,2003.
［9］Rogers D W O, Treurniet J. Monte Carlo calculated wall and axial non-uniformity corrections for primary standards of air kerma ［R］. NRCC Report PIRS-663,1999.
［10］ISBN 92-67-10188-9,Guide to the Expression of Uncertainty in Measurement［S］. |
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2016, Vol. 37 
