Probing Sub-GeV Dark Matter with Superfluid Helium

by Vetri Velan (Rutgers, State Univ. of New Jersey (US)), Vetri Velan (Berkeley)

Tuesday 30 Jan 2018, 12:30 → 13:30 US/Pacific

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We propose a new dark matter detector which will be sensitive to nuclear recoils of sub-GeV dark matter, using superfluid helium as a target. Superfluid helium has many merits as a detector target: these include good kinematic matching to low mass dark matter, feasibility for achieving good intrinsic radiopurity, and its unique ability to be cooled down to milli-Kelvin temperatures while remaining as a liquid. We propose to read out our recoil signal by bolometry. Bolometers submerged in the liquid will measure prompt scintillation photons, while rotons and phonons will be detected by quantum evaporating helium atoms off the liquid surface, into vacuum, and then onto a bolometer. The binding energy from helium absorption to the bolometer surface allows for the amplification of these quantum evaporation signals, allowing us to potentially reach recoil energy thresholds below 10 eV. Taking into account the relevant backgrounds and the detector discrimination power, sensitivity projections show that a small detector (~kg scale) can already explore new parameter space."

Velan_SLAC_Exp_Seminar_20180130.pdf