Abstract
Many actinides emit intense L X-rays consecutively to their decay. However the intensities of these X-rays are not well known: they are generally calculated with relatively large uncertainties and do not always agree with existing measurements. The latter ones are obtained with semiconductor spectrometers, but due to their insufficient energy resolution, these detectors are not able to separate the many X-ray lines and to give detailed emission intensities. So new measurements of precise and detailed L X-ray emission intensities are required. These would be beneficial on the one hand for the knowledge of the decay schemes and on the other hand as reference data for end-users of X-ray spectrometry. Therefore a spectrometer with a high energy resolution has been developed based on the technology of metallic magnetic calorimeters. The L X-ray spectra from $^{241}$Am and $^{210}$Pb decays show a FWHM energy resolution of 26 eV associated with a constant detection efficiency between 5 and 26 keV. With such performance, about 30 relative L X-ray intensities can be determined for $^{241}$Am and $^{210}$Pb. The measured emission intensities of L X-ray groups are compared with those published as obtained with conventional techniques; the good agreement between the data validated our technique.
Highlights
Many actinides emit intense L X-rays consecutively to their decay
More accurate decay data of heavy elements and actinides are beneficial for fission reactors, for nuclear safeguards, for the environmental survey of specific actinides and their decay chains; improved decay data extend the scientific knowledge for physics research and non-energy applications
– L X-ray spectra are complex, tens of X-ray transitions are concentrated in a narrow energy range of about 15 keV and conventional detector technology, i.e., a semiconductor spectrometer, is not able to separate the many X-ray lines;
Summary
More accurate decay data of heavy elements and actinides are beneficial for fission reactors (safety, waste management. . . ), for nuclear safeguards, for the environmental survey of specific actinides and their decay chains; improved decay data extend the scientific knowledge for physics research and non-energy applications. Actinides are relevant because most of them emit intense L X-rays, ranging from a few photons per 100 decays up to one hundred (Table 1). These actinides decay by alpha or beta minus emission and the daughter nuclei de-excite through many gamma transitions. – L X-ray spectra are complex, tens of X-ray transitions are concentrated in a narrow energy range of about 15 keV and conventional detector technology, i.e., a semiconductor spectrometer, is not able to separate the many X-ray lines;. – It will provide reliable data for the analysis of the L X-ray spectra by end-users; Spectrometers with improved energy resolution are indispensable to separate the many L X-ray lines and measure their emission intensities. A dedicated ultra-high energy resolution spectrometer, called SMX3, based on Metallic Magnetic Calorimeter (MMC) technology has been developed
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