Determination of L-X-ray line emission intensities in the decay of Cm-244 with a metallic magnetic calorimeter

摘要

Emissions of L-X-rays by actinides are quite intense due to the large internal conversion coefficients of the gamma transitions. These emissions can be beneficial for the quantitative analysis of actinides by photon spectrometry, however the L X-rays emitted by radionuclides are generally not well known. Several studies explored the L-X-ray regions of actinides and measured total intensities of L-X-ray groups with large uncertainties up to 10%. However, they cannot resolve the individual L-X-ray lines due to the limited energy resolution (of the order of 200 eV (FWHM) at 25 keV) of the semiconductor detectors. The present work shows and discusses the measurement of individual L-X-ray emission intensities emitted by Cm-244 using an ultra-high-resolution spectrometer. The used spectrometer is a Metallic Magnetic Calorimeter (MMC) conceived for photon spectrometry below 100 keV with an energy resolution of 37 eV at 20 keV and a nearly constant efficiency over the L X-ray energy range. A high-resolution spectrum with a counting statistics of 4.6 × 106 counts was obtained. The spectrum processing allowed to determine the individual emission intensities of 30 L-X-ray lines despite the narrow energy spacing.