Directional detectability of dark matter with single phonon excitations: Target comparison

Single phonon excitations are sensitive probes of light-dark matter in the keV-GeV mass window. For anisotropic target materials, signal depends on direction incoming dark wind and exhibits a daily modulation. We discuss detail various sources anisotropy carry out comparative study 26 crystal targets, focused sub-MeV benchmarks. compute modulation reach for most promising corresponding to cross section where can be observed given exposure, which allows us combine strength matter-phonon couplings amplitude highlight ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ (sapphire), ${\mathrm{CaWO}}_{4}$, h-BN (hexagonal boron nitride) as best polar materials recovering signal, feature $\mathcal{O}(1--100)%$ variations detection rates throughout day, depending interaction. The directional nature single offers useful handle mitigate backgrounds, is crucial fully realizing discovery potential near future experiments.