QUEST-DMC: Looking for Low Mass Dark Matter using Superfluid ³He

We present the results of the first runs of the QUEST-DMC experiment that aims to detect low mass sub-GeV dark matter, using a small 0.1g target of superfluid ³He [1,2]. The prototype runs were made at pressures from 0 to 29 bar and superfluid temperatures down to 0.15 T/T_c, achieving an energy threshold of 3.5 keV. To reach world-leading sensitivity and exposure to spin-dependent (and independent) interactions with sub-GeV dark matter, we have now combined SQUID-based readout with low-background materials, which should allow reducing the threshold to the eV level. Here we report on the first measurements from the cooldown of this upgraded facility and compare to previous experiments that used conventional readout techniques.

This abstract is submitted on behalf of the QUEST-DMC collaboration.

[1] Eur.Phys. J. C 84, 248 (2024)

[2] J. Low Temp. Phys. 215, 465 (2024)