We present first significant limits on WIMP dark matter by the phonon-light technique, where combined phonon and light signals from a scintillating cryogenic detector are used. Data from early 2004 with two 300 g CRESST-II prototype detector modules are presented, with a net exposure of 20.5 kg days. The modules consist of a CaWO 4 scintillating "target" crystal and a smaller cryogenic light detector. The combination of phonon and light signals leads to a strong suppression of non-nuclear recoil backgrounds. Using this information to define an acceptance region for nuclear recoils we have 16 events from the two modules, corresponding to a rate for nuclear recoils between 12 and 40 keV of (0.87± 0.22) events/(kg day). This is compatible with the rate expected from neutron background, and most of these events lie in the region of the phonon-light plane anticipated for neutron-induced recoils. A particularly strong limit for WIMPs with coherent scattering results from selecting a region of the phonon-light plane corresponding to tungsten recoils, where the best module shows zero events.

We report measurements of the de Haas-van Alphen (dHvA) effect in the quasi-two-dimensional organic metal κ-(BEDT-TTF)2Cu(NCS)2 by means of a capacitive torquemeter. The experiments were carried out in magnetic fields up to 29.5 T, at temperatures down to 0.4 K and for tilt angles θ between -35° and 80°. In the angular dependence of the fundamental frequency we observed five spin-zeros, the absolute amplitude at θ = 0° amounts to μ0M = 4·10-6 T (B = 13.8 T, T = 1.4 K). Above 15 T a series of high-frequency oscillations due to magnetic breakdown is observed. The main breakdown orbit could be detected up to θ = 55°, the angular dependence is also characterized by spin-splitting effects. We determined the effective cyclotron mass of three different breakdown orbits at θ = 5.6°. Our results are in good agreement with a simple model of magnetic breakdown. The occurrence of weak oscillations forbidden within this model is discussed.

We present systematic magnetic torque studies of the "magnetic field -temperature" phase diagram of the layered organic conductor α-(BEDT-TTF)2KHg(SCN)4 at fields nearly perpendicular and nearly parallel to the highly conducting plane. The shape of the phase diagram is compared to that predicted for a charge-density-wave system in a broad field range.

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We present a new technique developed for the measurement of the scintillation efficiency of nuclear recoils in solid scintillators. Using this technique we measured the quenching of the scintillation efficiency for the various recoiling nuclei in CaWO 4 crystals which are used in direct Dark Matter searches.