High‐resolution, energy‐dispersive microcalorimeter spectrometer for X‐ray microanalysis
We have developed a prototype X‐ray microcalorimeter spectrometer with high energy resolution for use in X‐ray microanalysis. The microcalorimeter spectrometer system consists of a superconducting transition‐edge sensor X‐ray microcalorimeter cooled to an operating temperature near 100 mK by a compact adiabatic demagnetization refrigerator, a superconducting quantum interference device current amplifier followed by pulse‐shaping amplifiers and pileup rejection circuitry, and a multichannel analyser with computer interface for the real‐time acquisition of X‐ray spectra. With the spectrometer mounted on a scanning electron microscope, we have achieved an instrument response energy resolution of better than 10 eV full width at half‐maximum (FWHM) over a broad energy range at real‐time output count rates up to 150 s −1 . Careful analysis of digitized X‐ray pulses yields an instrument‐response energy resolution of 7.2 ± 0.4 eV FWHM at 5.89 keV for Mn Kα 1,2 X‐rays from a radioactive 55 Fe source, the best reported energy resolution for any energy‐dispersive detector.