First Demonstration of the HeRALD Superfluid Helium Detector Concept

Abstract

The SPICE/HeRALD collaboration is performing R&D to enable studies of sub-GeV dark matter models using a variety of target materials. Here we report our recent progress on instrumenting a superfluid ${}^4$He target mass with a transition-edge sensor based calorimeter to detect both atomic signals (scintillation) and ${}^4$He quasiparticle (phonon and roton) excitations. The sensitivity of HeRALD to the critical "quantum evaporation" signal from ${}^4$He quasiparticles requires us to block the superfluid film flow to the calorimeter. We have developed a heat-free film-blocking method employing an unoxidized Cs film, which we implemented in a prototype "HeRALD v0.1" detector of ~10 g target mass. This article reports initial studies of the atomic and quasiparticle signal channels. A key result of this work is the measurement of the quantum evaporation channel's gain of 0.15 $\pm$ 0.01, which will enable ${}^4$He-based dark matter experiments in the near term. With this gain the HeRALD detector reported here has an energy threshold of 145 eV at 5 sigma, which would be sensitive to dark matter masses down to 220 MeV/c${}^2$.

14 pages, 9 figures

References in corpus (8)

• EXCESS workshop: Descriptions of rising low-energy spectra
• Maximizing Direct Detection with Highly Interactive Particle Relic Dark Matter
• A Stress Induced Source of Phonon Bursts and Quasiparticle Poisoning
• Latest observations on the low energy excess in CRESST-III
• Scintillation yield from electronic and nuclear recoils in superfluid ${}^4$He
• Observation of Crossover from Ballistic to Diffusion Regime for Excimer Molecules in Superfluid ${}^4$He
• Signatures and Detection Prospects for sub-GeV Dark Matter with Superfluid Helium
• The Thermal Conductance of Sapphire Ball Based Detector Clamps

Cited by in corpus (5)

• Resonant or asymmetric: The status of sub-GeV dark matter
• First Limits on Light Dark Matter Interactions in a Low Threshold Two Channel Athermal Phonon Detector from the TESSERACT Collaboration
• Low-Energy Backgrounds in Solid-State Phonon and Charge Detectors
• Low-Energy Calibration of SuperCDMS HVeV Cryogenic Silicon Calorimeters Using Compton Steps
• Signal partitioning in superfluid ${}^4$He: a Monte Carlo approach