The absolute counting of 125I

The Institute of Nuclear Energy Research (INER) participated in a comparison of activity organized by the Electrotechnical Laboratory (ETL, Japan). At this occasion,125I was measured. Seven laboratories of the Asia Pacific region carried out measurements and ETL, at the same time, took part in BIPM SIR measurements. Two measurement methods developed by INER, the sum-peak coincidence counting with two 76×76 mm NaI(Tl) detectors and the 4πe-X coincidence counting technique with efficiency extrapolation, were used to standardize the activity of 125I. The results from the two methods are 2.6% different. INERʹs results agree with the results of the regional comparison and the BIPM SIR.