Comparison of the standards for air kerma of the MKEH and the BIPM for¹³⁷Cs gamma radiation

An indirect comparison of the standards for air kerma of the Magyar Kereskedelmi Engedelyezesi Hivatal (MKEH), Hungary, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the Cs-137 radiation beam of the BIPM in October 2009. The comparison result, expressed as a ratio of the MKEH and the BIPM calibration coefficients of a transfer chamber for air kerma, is 1.0053 with a combined standard uncertainty of 2.5 x 10(-3). The result of the earlier direct comparison in Cs-137 gamma rays, made in 1994, was 0.9954(30); taking into account the changes made recently to both standards, the 1994 result becomes 1.0038 (30), in agreement with the present comparison result.