Development of a microcalorimeter for measurement of L X-rays emitted from transuranium elements

We fabricated a transition-edge sensor (TES) microcalorimeter for spectroscopic measurements of L X-rays emitted by transuranium (TRU) elements. A Pu L X-ray energy spectrum was obtained by irradiation with L X-rays emitted by a 244Cm source to the TES microcalorimeter. The energy resolution was evaluated to be 64 eV at the full width at half maximum (FWHM) for L X-rays at 14.28 keV. The obtained L X-ray spectrum indicated that the TES microcalorimeter made it possible to distinguish between the L X-ray lines of TRU elements.