Application of the Neganov-Luke Effect for Scintillation Light Detection

Christian Isaila1, Oliver Boslau2, Christian Ciemniak1, Chiara Coppi1, Franz von Feilitzsch1, Achim Gütlein1, Josef Kemmer2, Jean-Come Lanfranchi1,
Andreas Pahlke2, Sebastian Pfister1, Walter Potzel1, Sabine Roth1, Wolfgang Westphal1, Florian Wiest2

1 Technische Universität München, Physik Department E15, James-Franck-Str., 85748 Garching, Germany
2 KETEK GmbH, Hofer Strasse 3, 81737 München, Germany


The simultaneous measurement of the phonons and the scintillation light generated in CaWO4 provides an efficient technique for the active suppression 
of the background induced by electron recoils in the CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) experiment. The phonon signal is read out
by a transition edge sensor (TES) on the CaWO4 crystal. The scintillation light is measured by a cryogenic light
detector consisting of a semiconductor absorber equipped with a TES. Taking into account that only a small fraction (about 1%) of the energy deposited in
the crystal is detected as light very sensitive light detectors are required for an efficient background discrimination. The threshold of the light detectors can be improved by drifting the electron-hole pairs generated by the scintillation photons by an applied
electric field. Thus additional phonons are created leading to an amplification of the thermal signal. For an efficient charge collection substrates with low trap densities 
are required. For this purpose and for electrical decoupling the TES is glued onto the drift device. Results from measurements with Neganov-Luke amplification using glued transition edge sensors will
be presented.