EDS x-ray microcalorimeters with 13 eV energy resolution

Abstract

Although Si- and Ge-based Energy Dispersive Spectroscopy (EDS) detectors are by far the most commonly used x-ray spectrometers for microanalysis, they are limited by energy resolutions on the order of 100 eV. This low energy resolution is insufficient to clearly resolve many peak overlaps between Kα x-ray lines of different elements. In addition, many L and M lines of heavier elements fall in the 100 eV to 2 keV energy range, making it difficult in complicated spectra to identify and quantify the presence of technologically important lighter elements. Higher energy resolution and good count rates are necessary to provide improved limits of detectability.We are developing a cryogenic x-ray microcalorimeter with significantly improved energy resolution and a count rate and detector area suitable for EDS microanalysis. In a calorimeter, the energy of an x-ray is converted to heat, and a measurement of the temperature rise of the detector gives the deposited photon energy. Our microcalorimeter detector consists of a normal-metal x-ray absorber which is in thermal and electrical contact with a superconducting transition-edge sensor (TES).