To establish the national primary standard for beta radiation tissue absorbed dose and to achieve international equivalence,the National Institute of Metrology(NIM)of China participated in the BIPM KCDB:EURAMET.RI(Ⅰ)-S16 comparison that organized by EURAMET(European Association of National Metrology Institutes)and coordinated by the Physikalisch-Technische Bundesanstalt(PTB)in 2019.The circulation of the chamber and of the electronic measurement system will be effected in a star pattern,with both devices being sent back by every five participants to the pilot laboratory for testing.16 institutes from 16 different countries will calibrate the comparison device according to their quality system in beta reference fields of the radionuclides 147Pm,85Kr,90Sr/90Y and 106Ru/106Rh.NIM calibrated the transfer ionization chambers using its beta radiation tissue absorbed dose primary standard,determining the calibration factors for Hp(0.07)at incident angles of 0°,45°,and 60° in the radiation field of 85Kr and 90Sr/90Y sources,as well as the calibration factors for Hp(3)at various angles for the 90Sr/90Y source.The calibration factors obtained in this work were compared with the reference values provided by EURAMET.The relative deviations of the calibration factors for Hp(0.07)at incident angles of 0°,45°,and 60° from the 90Sr/90Y and 85Kr sources compared to the reference values are better than±0.8％;The relative deviations of the calibration factors for Hp(3)at incident angles of 0°,45°,and 60° from the 90Sr/90Y source compared to the reference values are better than±0.9％.The relative deviations for the nine results are better than±1％.These results were incorporated into the International Bureau of Weights and Measures(BIPM)Key Comparison Database(KCDB),achieving international mutual recognition for the personal dose equivalents Hp(0.07)and Hp(3)in beta radiation.
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