Standardisation of (56)Co and (57)Co using software coincidence counting system.
Activities of the radionuclides (56)Co and (57)Co were determined by the efficiency extrapolation method applied to 4pi(PC)-gamma coincidence counting. Solutions of (56)Co usually contain a significant amount of (57)Co and (58)Co, so the measured activity of (56)Co requires correction. When the conventional coincidence method is used for (56)Co standardisation, the corrections are derived from the dependence of Proportional Counter (PC) detection efficiencies for (57)Co and (56)Co measured using sources with mixture of (56)Co and (57)Co, which is complicated. These difficulties were reduced by means of a software coincidence method, with a HPGe detector in gamma channel, where the detection efficiencies were evaluated directly from the records of coincidence measurements of standardised sources. In the case of (57)Co standardisation, the software coincidence counting system was applied for the evaluation of optimal setting of coincidence parameters. The results obtained by software coincidence counting system were compared with those obtained by the conventional coincidence method.
Havelka
Miroslav
M
Czech Metrology Institute, Inspectorate for Ionizing Radiation, Radiová 1, 102 00 Prague, Czech Republic. mhavelka@cmi.cz
Sochorová
Jana
J