Prototype of the high sensitive X-ray microcalorimeter for X-ray imaging

An X-ray microcalorimeter is a high performance X-ray spectrometer that can achieve both high energy resolution of conventional wavelength dispersive spectrometers (WDS) and high quantum efficiency of energy dispersive spectrometers (EDS). The energy resolution can be theoretically improved to about 1 eV, which value is 120 times better than that of conventional Si(Li) spectrometers and nearly 100% of quantum efficiency can be achieved using microabsorbers. In order to realize high energy-resolution X-ray imaging using an array of X-ray microcalorimeters, two types of 2×2 X-ray microcalorimeter arrays were fabricated and tested. Using an X-ray microabsorber so-called “mushroom-shaped” X-ray microabsorber, the filling factor was enhanced to about 70%. We tested Sn and Bi as an X-ray microabsorber. Consequently, the Sn absorber degrades the energy resolution because of the long time constant. This problem was cleared using the Bi microabsorber. The achievable energy resolution was also investigated. As a result, the energy resolution of 6.3 eV was obtained with the test device.