A method for radiation dose assessment of β-rays and γ-rays in mixed β-γ fields
Objective To test a new method with thermoluminescent dosimeters(TLDs)to determine the β-ray and γ-ray doses of β-γ mixed radiation fields.Methods TLDs for personal dose monitoring were irradiated in the reference radiation fields of β-rays(90Sr/90Y,85Kr)and γ-rays(137Cs).Across the range of 2.0-15.0 mSv,the linearity of TLD response and normalized response with respect to 137Cs were determined at the depths of Hp(10)and Hp(0.07).Using TLD detector readings at the depths of Hp(10)and Hp(0.07),β-and γ-ray doses in the mixed radiation fields were determined,and the result were verified.Results For Hp(10)and Hp(0.07)under γ-ray exposure and Hp(0.07)under β-ray exposure,the coefficient of determination(R2)were all＞0.998.For the 90Sr/90Y source and85 Kr source,the average values of response values normalized with respect to 137Cs at different doses were 1.14 and 0.18,respectively;and the normalized response values derived from the slope values of the dose-response curves for the two sources were 1.17 and 0.18,respectively.The ratios of measurements of Hp(10)to Hp(0.07),kR,for the 85Kr source were close to 0,while the kR values for the 137Cs source were close to 1.Using the average value of kR and the slope value of kR for calculation,the maximum relative deviations between the calculated values and conventional values for Hp(10),Hp(0.07)γ,and Hp(0.07)β were 6.1％ and 6.0％ ,respectively.Conclusions This method can be applied for the assessment of β-ray and γ-ray doses in β-γ mixed radiation fields of a single β source and single γ source.
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