Measurement of the ionization yield from nuclear recoils in liquid xenon between 0.3 -- 6 keV with single-ionization-electron sensitivity

Understand

Dual-phase xenon TPC detectors are a highly scalable and widely used technology to search for low-energy nuclear recoil signals from WIMP dark matter or coherent nuclear scattering of $\sim$MeV neutrinos.

• Such experiments expect to measure O(keV) ionization or scintillation signals from such sources.
• However, at $\sim1\,$keV and below, the signal calibrations in liquid xenon carry large uncertainties that directly impact the assumed sensitivity of existing and future experiments.
• In this work, we report a new measurement of the ionization yield of nuclear recoil signals in liquid xenon down to 0.3$\,$keV$\,\,$-- the lowest energy calibration reported to date -- at which energy the average event produces just 1.1~ionized~electrons.