Standardization of a 204Tl radioactive solution

The standardization of 204Tl is described. The efficiency tracing technique was applied using 134Cs as tracer. The 4πβ–γ coincidence system was used for the calibration. The (Laboratorio de Metrologia Nuclear) has participated in this comparison in collaboration with the Laboratório Nacional de Metrologia das Radiações Ionizantes, from Rio de Janeiro. Independent results using different techniques were developed by each of these laboratories and included in the comparison.