Speaker
Description
Superfluid helium-3 bolometers can exploit the extremely low superfluid gap (10e-7 eV) to give ultra-low energy threshold dark matter direct detection searches. This gives the potential to probe dark matter models with sub-GeV/c2 masses, in particular offering world-leading sensitivity to spin-dependent interactions. Realising this requires operation at ultra-low temperatures in the 100s uK regime, where helium-3 in the B phase has extremely low specific heat, coupled with low noise detector readout.
The detection scheme for the QUEST-DMC programme is based on the measurement of quasiparticle density in superfluid helium-3 using novel vibrating wire resonators with sub-micron diameter and SQUID readout [1]. We have completed several experimental runs developing this technique, with resonator characterisation and bolometry, recently reaching new lowest temperatures of 130 uK. Energy calibration using direct heat injection from a second vibrating wire has been carried out and complimentary calibration with 6 keV gamma radiation produced by a 55Fe source is underway. I will discuss the noise performance and the resultant energy resolution of the bolometer. The measured bolometer energy spectrum will be compared to Monte Carlo simulations of the cosmic ray and radiogenic backgrounds incident on the helium-3 bolometer.
[1] S. Autti et al. European Physical Journal C 84, 248 (2024).
| Primary Abstract Topic | Experiment: WIMPs |
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