  We have combined two low-threshold detector technologies to develop a
large-mass, low-threshold detector system that simultaneously measures the
athermal phonons in a sapphire detector while an adjacent silicon high-voltage
detector detects the scintillation light from the sapphire detector. This
detector system could provide event-by-event discrimination between electron
and nuclear events due to the difference in their scintillation light yield.
While such systems with simultaneous phonon and light detection have been
demonstrated earlier with smaller detectors, our system is designed to provide
a large detector mass with high amplification for the limited scintillation
light. Future work will focus on at least an order of magnitude improvement in
the light collection efficiency by having a highly reflective detector housing
and custom phonon mask design to maximize light collection by the silicon
high-voltage detector.
