A new biasing technique for transition edge sensors with electrothermal feedback

We have developed a new operating mode for superconducting transition edge sensors (TES) used in cryogenic particle detection which use electrothermal feedback (ETF). By using the new technique with the optical photon detecto rs our group has developed, we have been able to reduce the decay time of t he pulses from the detector by more than a factor of five. The technique in volves reducing the voltage bias across the tungsten superconducting detect or during a pulse. By reducing the voltage during a pulse, there is an addi tional reduction in joule heating which speeds up the recovery of the detec tor. In theory, the technique reduces the decay time of the pulses which al lows for higher maximum count rates. In addition to a brief theoretical ana lysis of the benefits of the technique, we present experimental results and analysis demonstrating a pulse decay time reduction by a factor of five.