Comparison of the standards for absorbed dose to water of the ARPANSA and the BIPM for 60Co γ radiation

A comparison of the standards for absorbed dose to water of the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Australia, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in June 2010 under the auspices of the key comparison BIPM.RI(I)-K4. The comparison result, based on the calibration coefficients measured for two transfer standards and expressed as a ratio of the ARPANSA and the BIPM standards for absorbed dose to water, is 0.9973 (53). This result replaces the 1997 ARPANSA value of 1.0024 (30) in this key comparison. The degrees of equivalence for the ARPANSA and the other participants in this comparison have been calculated and the results are given in the form of a table for the national metrology institutes (NMIs) that have results published in this ongoing comparison for absorbed dose to water. A graphical presentation is also given. (authors)