Light Dark Matter Detection with Hydrogen-rich Crystals and Low-Tc TES Detectors

TL;DR

This paper explores hydrogen-rich crystals and low-temperature TES detectors for direct detection of sub-GeV dark matter, focusing on their signal mechanisms and potential to probe unexplored parameter space.

Contribution

It introduces hydrogen-rich crystals as detection media and discusses the development of ultra-sensitive low-Tc TES detectors for light dark matter searches.

Findings

Hydrogen-rich crystals emit infrared photons and phonons under excitation.

Low-Tc TES detectors can measure single photons and phonons with high sensitivity.

The approach can explore large uncharted parameter space of light DM.

Abstract

Direct detection of nuclear scatterings of sub-GeV Dark Matter (DM) particles favors low-Z nuclei. Hydrogen nucleus, which has a single proton, provides the best kinematic match to a light dark matter particle. The characteristic nuclear recoil energy is boosted by a factor of a few tens from those for larger nuclei used in traditional Weakly Interacting Massive Particle (WIMP) searches. Furthermore, hydrogen is optimal not only for spin-independent nuclear scatterings of sub-GeV DM, but also for spin-dependent nuclear scatterings, where large parameter space remains unconstrained. In this paper, we first introduce hydrogen-rich crystals, which include water ice, acetylene, anthracene, trans-stilbene, and naphthalene. These crystals emit two classes of signals under kinetic excitations. One class of the signals is infrared photons, which are from optically active fundamental vibrational modes of molecules and are at corresponding characteristic wavelengths. The other is acoustic phonons, and optical phonons that decay into acoustic phonons. We then discuss the technical status and future researches of low-Tc Transition-Edge Sensor (TES) detectors, which measure single infrared photons and a small flux of acoustic phonons with desirable sensitivities. With theoretical modeling to select the hydrogen-rich crystals for the optimized science reach, development of ultra-sensitive low-Tc TES detectors for readout, and experimentally characterizing transport properties of photons and phonons in the selected hydrogen-rich crystals, a direct detection experiment can be built for measuring the large unexplored parameter space of light DM particles.