Standardization of 192Ir solution at BARC

A radioactive solution of 192Ir was standardized at Bhabha Atomic Research Centre (BARC) under the international intercomparison programme of the Bureau International des Poids et Measures (BIPM) by 4πβ-γ coincidence and 4πγ counting techniques, which are primary and secondary methods of standardization, respectively. The activity concentration of the 192Ir solution obtained by the efficiency extrapolation technique and as reported to BIPM was 203.15 kBq g−1 with a combined uncertainty of ±0.3%. The activity concentration determined by 4πγ counting was 202.88 kBq g−1 with a combined uncertainty of ±1.3%. These measurement results are comparable within the uncertainty limits. Detailed uncertainty budget for both the primary and secondary methods are included.