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, D_w. The design of the Italian primary standard for absorbed dose to water D_w 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.