A SELF-BIASING CRYOGENIC PARTICLE DETECTOR UTILIZING ELECTROTHERMAL FEEDBACK AND A SQUID READOUT

We are developing and testing a new type of superconducting transition edge sensor for phonon mediated particle detection. This sensor consi sts of a superconducting tungsten thin film deposited on a silicon sub strate. The temperature of the film is held constant within the superc onducting transition (T-c approximate to 70 mK) by an electrothermal f eedback process, while the substrate temperature is well below the fil m temperature. Phonon energy deposited in the film is removed by a red uction in feedback Joule heating, which is measured using a series arr ay of DC SQUIDs. The resulting signals show improvements in linearity and signal to noise ratio over our previous transition edge sensors.