The simultaneous measurement of phonons and scintillation light induced by incident particles in a scintillating crystal such as CaWO4 is a powerful technique for the active rejection of background induced by gamma's and beta's and even neutrons in direct Dark Matter searches. However, less than ~1% of the energy deposited in a CaWO4 crystal is detected as light. Thus, very sensitive light detectors are needed for an efficient event-by-event background discrimination. Due to the Neganov-Luke effect, the threshold of low-temperature light detectors based on semiconducting substrates can be improved significantly by drifting the photon-induced electron-hole pairs in an applied electric field. We present measurements with low-temperature light detectors based on this amplification mechanism. The Neganov-Luke effect makes it possible to improve the signal-to-noise ratio of our light detectors by a factor of ~9 corresponding to an energy threshold of ~21 eV. We also describe a method for an absolute energy calibration using a light-emitting diode.
@article{arxiv.1106.0167,
title = {Low-Temperature Light Detectors: Neganov-Luke Amplification and Calibration},
author = {C. Isaila and C. Ciemniak and F. v. Feilitzsch and A. Gütlein and J. Kemmer and T. Lachenmaier and J. -C. Lanfranchi and S. Pfister and W. Potzel and S. Roth and M. v. Sivers and R. Strauss and W. Westphal and F. Wiest},
journal= {arXiv preprint arXiv:1106.0167},
year = {2012}
}