Radionuclide-free efficiency calibration of an HPGe detector using monochromatic photon beams calibrated with a cryogenic radiometer

A cryogenic electrical-substitution radiometer was used for the primary calibration of monochromatic photon beams at synchrotron, which are in turn employed to determine the intrinsic efficiency of an HPGe detector between 3.5 keV and 8 keV. This allowed the determination of the thickness of the dead layer, which enabled the calculation of the efficiency up to 55 keV, where the active thickness is not determinant. The geometrical efficiency was determined through the measurement of a radioactive source at variable distances.