International exercise on 124Sb activity measurements.

An international exercise, registered as EUROMET project no. 907, was launched to measure both the activity of a solution of 124Sb and the photon emission intensities of its decay. The same solution was sent by LNE-LNHB to eight participating laboratories. In order to identify possible biases, the participants were asked to use all possible activity measurement methods available in their laboratory and then to determine their reference value for comparison. Thus, measurement results from 4πβ–γ coincidence/anti-coincidence counting, CIEMAT/NIST liquid-scintillation counting, 4πγ counting with well-type ionization chambers and well-type crystal detectors were given. The results are compared and show a maximum discrepancy of about 1.6%: possible explanations are proposed.