Ponente
Descripción
Superfluid helium-3 bolometers can exploit the extremely low superfluid gap ($10^{-7}$ eV) to give ultra-low energy threshold dark matter direct detection searches. These can probe dark matter models with sub-GeV/c$^2$ masses, in particular offering world-leading sensitivity to spin-dependent interactions. Realising this requires operation at ultra-low temperatures in the 100s μK 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 demonstrate resonator characterisation and bolometry, including non-linear operation. Energy calibration using direct heat injection from a second vibrating wire has been carried out and a gamma radiation source has been installed for complimentary calibration. Noise performance and the resultant energy resolution of the bolometer will be discussed. 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).
