Superconducting Detectors for Superlight Dark Matter

We propose and study a new class of superconducting detectors that are sensitive to O(meV) electron recoils from dark matter–electron scattering. Such devices could detect dark matter as light as the warm dark-matter limit, m_X≳1  keV. We compute the rate of dark-matter scattering off of free electrons in a (superconducting) metal, including the relevant Pauli blocking factors. We demonstrate that classes of dark matter consistent with terrestrial and cosmological or astrophysical constraints could be detected by such detectors with a moderate size exposure.