SiC Detectors for Sub-GeV Dark Matter

Abstract

We propose the use of silicon carbide (SiC) for direct detection of sub-GeV dark matter. SiC has properties similar to both silicon and diamond, but has two key advantages: (i) it is a polar semiconductor which allows sensitivity to a broader range of dark matter candidates; and (ii) it exists in many stable polymorphs with varying physical properties, and hence has tunable sensitivity to various dark matter models. We show that SiC is an excellent target to search for electron, nuclear and phonon excitations from scattering of dark matter down to 10 keV in mass, as well as for absorption processes of dark matter down to 10 meV in mass. Combined with its widespread use as an alternative to silicon in other detector technologies and its availability compared to diamond, our results demonstrate that SiC holds much promise as a novel dark matter detector.

Directional Detectability of Dark Matter With Single Phonon Excitations: Target Comparison

“…In the pursuit of sub-GeV DM, several new experimental concepts have been proposed. These include electron excitations in a variety of target systems [28][29][30][31][32][33][34][35][36][37][38][39][40] for DM with mass above an MeV, while phonon excitations [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55], with energies up to O(100) meV, have been shown to be especially sensitive to a wide range of DM models with masses down to a keV. This coupled with the fact that detector energy thresholds are approaching the O(100) meV range [56][57][58][59][60] makes phonon excitations an exciting avenue for DM direct detection.…”

“…Other targets have also been proposed individually, e.g. SiC [52], and there has been work on understanding the signal from multi-phonon excitations [51,54,55]. Similar to superfluid helium, a DM detector using a crystal target with phonon readout is also in the R&D phase of development [61].…”

“…In particular, we highlight the following targets in the main text: Al 2 O 3 (sapphire) and CaWO 4 , already utilized for DM detection and have a significant daily modulation; SiO 2 , shown to have a strong reach to several benchmark models; SiC, proposed in Ref. [52]; and h-BN (hexagonal boron nitride), a highly anisotropic material. Among them, Al 2 O 3 and CaWO 4 have the best prospects overall in terms of daily modulation reach and experimental feasibility.…”

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

“…However, it is insensitive to spin-dependent scatterings because 4 He has two protons and two neutrons and its net nuclear spin is zero. Crystalline solids are utilized with phonons [22][23][24][25], scintillation [22,25], ionization [27], ionization with a thermal gain [26], or low threshold thermal measurement [28]. However, the nuclei interacting with DM are much heavier than the proton mass and therefore are not optimal for kinetic energy deposition from light DM due to kinematic mismatch.…”

Dark matter daily modulation with anisotropic organic crystals

“…In molecular or solid-state systems, atoms are close enough that electronic orbitals overlap significantly, lowering the electronic excitation energies to the eV scale and thus allowing detection of DM particles with ∼ MeV-scale mass which carry eV-scale kinetic energy. Moreover, solidstate systems can exhibit anisotropic electronic wavefunctions (see for example [9,16,20,27,28,33]), enabling directional detection schemes which leverage the characteristic signature of the daily modulation of the direction of the DM wind in the lab frame (first noted in the context of multiple scattering from terrestrial overburden in [54][55][56], followed by the connection to directional detection in [57]).…”