Speaker
Description
The impact of time resolution on achievable sensitivity across different generation rates has been investigated for direct light dark matter searches using deep sub-electron noise silicon detectors. In relevant experiments --- most prevalent using Skipper CCD or RNDR-DEPFETs --- the effective exclusion parameter space is predominantly limited by mass, exposure and background. A faster readout reduces the probability of multi-electron background per readout cycle events, caused by pile-up of thermal generated single electron events, enabling a distinguishable separation between background events and expected dark matter signals for two or more electron events.
To quantify the correlation between time resolution and sensitivity, a modular python-based simulation framework was built, utilizing the DarkELF package to simulate dark matter--electron scattering, assuming idealized Poisson--Gaussian background modulation and detector specific timing and pixel architecture. This enables a trade-off study between time resolution and detector mass across different generation rates and evaluates whether improved time resolution can compensate for increased background or reduce the necessary exposure.
The studies are motivated by the DANAE experiment, which employs RNDR-DEPFET active pixel sensors with repetitive non-destructive readout for direct dark matter searches. Compared to Skipper CCDs, RNDR-DEPFETs exhibit larger pixels and therefore higher generation rates. Skipper CCD experiments achieve very low background levels but sequential operation results in comparatively long readout times. In contrast, DEPFET detectors can be parallelized and provide significantly shorter readout times. The presented analysis will quantitatively characterize sensitivity by comparing the size of achievable excluded parameter space for different pixel sizes, generation rates and masses. It will quantify the impact of time resolution depending on the generation rate per pixel --- and thus on pixel size. An approximate time resolution below $16\,\mathrm{s/readout}$ yields substantial improvements in exclusion reach for generation rates above $3 \times 10^{-3}\, e^{-}/\mathrm{readout/pixel}$.
| Main Contribution topic | Instrumentation for Dark Matter searches |
|---|---|
| Secondary contribution topic | Light Dark Matter |