Fabrication and characterization of superconducting X-ray calorimeters with transition edge sensors

We have developed superconducting calorimeters using transition edge sensors (TESs) for industrial X-ray microanalysis. To obtain high count rate, high reliability, and high energy resolution, a large format array of the sensors and an integration of a TES calorimeter and a SQUID amplifier are required. A novel calorimeter fabrication process has been established, in which a micro-machining technology using a silicon-on-insulator wafer was applied. A 4-pixel Au/Ti TESs calorimeter was fabricated using this process. SQUID amplifiers suitable for the calorimeter have also been designed and fabricated. It is expected to achieve a count rate per pixel of 7.1 kcps. The expected energy resolution including the SQUID contribution was estimated at 17-21 eV. It has been confirmed that the SQUID contribution for the current noise of our calorimeter can almost be ignored. It has also been confirmed that an array of 14 or more pixel are required that to achieve an effective count rate of more than 100 kcps.