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Communication Dans Un Congrès Année : 2023

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

Résumé

The efficiency calibration of spectrometers is traditionally based on the measurement of radioactive sources calibrated in activity and whose emission intensities are known. However, in the energy range below 60 keV, there is a lack of reliable tabulated emission intensities and some inconsistencies have been highlighted. Furthermore, if one aims to improve the measurement of emission probabilities, this approach implies the use of the same parameters that one intends to measure. The solution to these limitations is the use of photon fluxes whose intensity has been determined in an absolute way by another technique. Here we present the calibration of a high-purity germanium (HPGe) detector in the energy range from 3 keV to 60 keV through a procedure that involves the following sequence of steps: First, the intensity of a monochromatic photon beam was measured by means of a cryogenic electrical-substitution radiometer BOLUX (BOLometer for Use in the field of X-rays) . Cryogenic detectors are based on the measurement of the temperature rise experienced by an absorber when the radiation interacts with it. In particular, in electrical-substitution radiometers, the amount of incident energy is determined by finding the electrical power that must be dissipated in the material to get the same temperature increase than that obtained during the photonic heating. Second, these well-determined photon beams have been employed for the calibration of different photodiodes in terms of current induced per unit optical power (efficiency) at different photon energies. Finally, for each energy step, the efficiency calibration of an energy-dispersive spectrometer based on an HPGe detector was obtained by comparison with the primarily-calibrated photodiodes. The calibration measurements were performed at two different beamlines (Métrologie and PUMA) of the SOLEIL synchrotron facility, and different photodiodes were used to cover the energy range of interest. The experimental approach and efficiency results will be detailed. The final application of this study is the use of the radionuclide-free calibrated spectrometer to determine new values of absolute X-ray emission intensities for radionuclides, starting with 109Cd and 152Eu.[1] Applied Radiation and Isotopes, Volume 134, April 2018, Pages 131-136 [2] Presented at EXRS2022, submitted to X-Ray Spectrometry
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cea-04258120 , version 1 (25-10-2023)

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  • HAL Id : cea-04258120 , version 1

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Victor Hernandez-Elvira, Yves Ménesguen, Marie-Christine Lépy. Radionuclide-free efficiency calibration of an HPGe detector using monochromatic photon beams measured with a cryogenic radiometer. ICRM 2023 - 23rd International Conference on Radionuclide Metrology and its Applications, Mar 2023, Bucarest, Romania. ⟨cea-04258120⟩
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