DEVELOPMENT OF TI BASED TRANSITION EDGE SENSORS FOR CRYOGENIC DETECTORS
In the last decade transition Edge Sensors (TES) have found application both in calorimeters for particle detection and for high-resolution light detectors from X rays to the infrared waves. TES consists of a superconducting phase transition thermometer evaporated onto a substrate. The detector works within the superconducting-to-normal transition , where the strong temperature dependence of the electrical resistance makes the film a very sensitive thermometer. Among the superconducting materials,Ti films 1 and Ti based bilayers 2,3,4 have been investigated by several authors. Ti based TES operating around 300 mK have been used for X-ray detectors and for millimeter waves, both with a single layer 5,6,7 and with bilayers . At lower temperatures, TES have applications as sensors to detect dark matter in calorimetric experiments 12,13,14,15,16,17 and as photon counters in the UV-NIR region . In the case of a single layer, Tc depends mainly on the residual resistivity. In the case of bilayers, because of the proximity effect, it is possible to tune the transition temperature Tc according to the experimental requirements, by varying the relative thicknesses.