Towards improving the metrological performance of a graphite calorimeter for radiation dosimetry measurements

This paper summarizes the progress on enhancing the metrological performance of the Italian national standard of absorbed dose to water, a graphite calorimeter, in a water phantom, for radiation dosimetry measurements designed and built at ENEA-INMRI, National Institute of Ionizing Radiation Metrology in Italy. This constitutes the first application of graphite calorimetry in the mid-energy x-ray region, with generating voltages from 180 to 250 kV, in an effort to improve the measurement accuracy of the quantity absorbed dose to water, Dw. The design of the Italian primary standard for absorbed dose to water Dw is shown, together with a wide experimental campaign aimed at identifying the optimized instrument settings which allows improving the measurement repeatability and reducing the overall uncertainty budget.