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T: Fachverband Teilchenphysik

T 23: Postersitzung

T 23.12: Poster

Montag, 29. Februar 2016, 13:30–14:30, VMP4 Foyer

Characterization of scintillating CaWO₄ crystals for the CRESST experiment using two-photon excitation — •Raphael Hampf, Thomas Dandl, Andrea Münster, Lothar Oberauer, Sabine Roth, Stefan Schönert, and Andreas Ulrich — Physik-Department and Excellence Cluster Universe, Technische Universität München, D-85747 Garching

In the CRESST experiment for direct dark matter search, phonon and photon signals from cryogenic CaWO₄ crystals are used to search for WIMP-induced nuclear recoil events. We present a novel table-top setup in which the scintillation of CaWO₄ is induced by 0.7ns laser pulses of 355nm wavelength. The excitation occurs via two-photon absorption in the bulk material. The scintillation light is observed by time resolved optical spectroscopy. By varying the focusing of the laser-beam the excitation density can be made high enough to study quenching effects due to exciton-exciton annihilation. This allows to perform experiments to test models for the quenching factors of different ionizing projectiles in CaWO₄ which are used to identify these projectiles on an event by event basis.

This research was supported by the DFG cluster of excellence “Origin and Structure of the Universe”.