SQUID Based W-Al Quasiparticle Trapping Assisted Transition Edge Sensor
We have demonstrated a new type of phonon sensor for cryogenic particle detectors with a high-bandwidth SQUID readout. Our Quasiparticle trapping assisted Electrothermal feedback Transition edge sensor (QET) utilizes aluminum quasiparticle traps attached to a tungsten superconducting transition edge sensor patterned on a silicon substrate. The tungsten lines are voltage biased and self-regulate in the transition region. We have tested three versions of these detectors. One detector consisted of four QET sensors patterned on the surface of a 1 cm × 1 cm × 1 mm silicon substrate. With this detector, we have shown an energy resolution of ∼400 eV FWHM and position sensitivity of ∼0.3 mm for 6 keV X-rays from an 55Fe source. We tested a second detector identical to the first but with the addition of an ionization sensor. With information from the ionization channel, we were able to distinguish electron-recoil events from nuclear-recoil events. Most recently, we have tested a 2 cm × 2 cm × 2 mm detector with four QET sensors.
Nam, S. W., Cabrera, B., Chugg, B., Clarke, R. M., Fertig, C., Irwin, K. D., & Young, B. A. (1996). SQUID based W-Al quasiparticle trapping assisted transition edge sensor. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 370(1), 187–189. https://doi.org/10.1016/0168-9002(95)01083-1