Exposure and air-kerma standards for cobalt-60 gamma rays

The implementation of the measuring conditions for the determination of the quantities exposure and air-kerma for Cobalt-60 gamma rays have been done at the Laboratorio Nacional de Metrologia das Radiacoes Ionizantes (LNMRI). Several years of work have already been done, and the results so far indicate that both quantities can be measured accordingly with the recommendations of the International Organizations and with uncertainties comparable with the ones practiced in similar laboratories. The comparisons done with the data obtained at the Bureau International des Poids et Mesures with their standards and experimental conditions have shown an excellent agreement, which strongly indicates that the LNMRI standards have an appropriate design and characteristics to be standards of high quality and performance. The efforts made during the last years to accomplish this aim, have been successful. Hence, the LNMRI is now in position to measure those quantities and to proceed with the periodical international intercomparisons in order to maintain the traceability to the International Metrology Network. (author)