TES X-ray microcalorimeters for X-ray astronomy and material analysis

TES X-ray microcalorimeter arrays provide not only high-energy resolution (FWHM < 10eV) in X-ray spectroscopy but also imaging and high-counting-rate capabilities. They are very promising spectrometer for X-ray astronomy and material analysis. In this paper, we report our recent progress. For material analysis, we have fabricated 8 × 8 format array with a fast signal response ( 40 µs) and proved the energy resolution of 5.8 eV FWHM at 5.9 keV. We developed common biasing scheme to reduce number of wirings from room temperature to the cryogenic stage. From measurements using the newly-designed common-bias SQUID array amplifier chips, and from numerical simulations, we demonstrated that signal cross talks due to the common bias is enough small. For space applications, we are developing frequency-division signal multiplexing system. We have fabricated a baseband feedback system and demonstrated that the noise added by the feedback system is about 4 eV FWHM equivalent for 16 ch multiplexing system. The digital to analog converter (DAC) dominates the noise, and needs be reduced by a factor of four for future astronomy missions.