Self-cooling cryogenic microcalorimeters made of SINIS junctions

High-quality low-leakage SINIS devices made of Al–AlMn–Al layers were fabricated for energy dispersive single photon detection. Information on different heat flow channels was extracted from the measured dynamics of detector signals due to X-ray events. At the optimum operation point, the extracted effective electron temperature decreased from 88 down to 43 mK due to self-cooling, roughly doubling the detector sensitivity.