  We report the first demonstration of a phonon-mediated silicon detector
technology that provides a primary phonon measurement in a low-voltage region,
and a simultaneous indirect measurement of the ionization signal through
Neganov-Trofimov-Luke amplification in a high voltage region, both in a
monolithic crystal. We present characterization of charge and phonon transport
between the two stages of the detector and the resulting background
discrimination capability at low energies. This new detector technology has the
potential to significantly enhance the sensitivity of dark matter and coherent
neutrino scattering experiments beyond the capabilities of current technologies
that have limited discrimination at low energies.
