Speaker
Description
Direct dark matter searches in cryogenic experiments such as COSINUS rely on superconducting transition-edge sensors (TES). Operating temperatures of about 15 mK enables low-noise as well as low heat capacity of all parts and therefore good sensitivity to small energy depositions. However, not all noise sources are fully understood yet, and measurements show deviations from current noise models. To reach targeted sensitivity and thresholds, strategies have been developed to identify operating points (OPs) in the transition that optimize the signal-to-noise ratio (SNR). One important tool for that are control pulses (CPs), which are artificial particle pulses injected by an external heater resistor. Since CPs are driving the TES out of transition, their height provides direct information about the current position in the transition. Another challenge is maintaining the desired OP for operating periods spanning more than a year. This is usually regulated by a PID tuner, which controls the heater dependent on the height of the injected CPs. A higher number of CPs can increase the stability but also increases dead time, requiring a trade-off between stability and exposure time. This contribution gives a brief overview of OP-optimization and stabilization approaches for COSINUS detectors and also discusses future developments, in particular the modulation of the TES current bias. The latter would make CPs obsolete and also enable new read-out schemes such as frequency-division multiplexing.
| Main Contribution topic | Instrumentation for Dark Matter searches |
|---|---|
| Secondary contribution topic | Direct detection |