CRESST is an experiment for the direct detection of dark matter, capable of detecting nuclear recoils down to 10 eV, which results in an impressive sensitivity for sub-GeV dark matter particles. For a better understanding of the measured background a background model is developed. The background components are considered via Geant4 simulations. At the current state, the CRESST background model only considers bulk contaminations and treats all detector surfaces as perfect plains. This contribution presents potential effects of a surface contamination with radiogenic nuclides, in combination with the influence of the crystals surface roughness. Nuclide decays near the crystal surface may lead to partial energy deposition inside the detector, potentially causing MeV energy events to influence the background in the keV energy range. Since default Geant4 is not capable of simulating a rough surface, a new extension for simulating a rough surface is developed and the impact of different roughness configurations is studied.

The Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) experiment employs scintillating crystals at extremely low temperatures (O 10mK) to search for nuclear recoils from hypothetical dark matter (DM) particles. CRESST has achieved thresholds below 100 eV with a wide range of target materials including CaWO4, LiAlO2, Al2O3, and Si. However, at these energies, the ability to discriminate between potential DM signals and electromagnetic background is insufficient. A detailed Geant4-based electromagnetic background model was developed for CRESST and is being continuously adapted to CRESST's current inventory of detector modules. We use a high-dimensional Bayesian likelihood fit of spectral templates to the measured spectrum to infer activities of various background sources. A template for the calibration source used to calculate the energy scale will be included in the likelihood fit. We present the status of CRESST's background model, and results from the simulation of the energy calibration. Our future plans of improving the background model are also discussed.

In the past decades, numerous experiments have emerged to unveil the nature of dark matter, one of the most discussed open questions in modern particle physics. Among them, the CRESST experiment, located at the Laboratori Nazionali del Gran Sasso, operates scintillating crystals as cryogenic phonon detectors. In this work, we present first results from the operation of two detector modules which both have 10.46 g LiAlO$_2$ targets in CRESST-III. The lithium contents in the crystal are $^6$Li, with an odd number of protons and neutrons, and $^7$Li, with an odd number of protons. By considering both isotopes of lithium and $^{27}$Al, we set the currently strongest cross section upper limits on spin-dependent interaction of dark matter with protons and neutrons for the mass region between 0.25 and 1.5 GeV/c$^2$.

We present the most recent solar neutrino results from the Borexino experiment at the Gran Sasso underground laboratory. In particular, refined measurements of all neutrinos produced in the pp fusion chain have been made. It is the first time that the same detector measures the entire range of solar neutrinos at once. These new data weakly favor a high-metallicity Sun. Prospects for measuring CNO solar neutrinos are also discussed.

In CRESST-III, 10 cryogenic detector modules optimized for low energy thresholds were operated for almost two years (May 2016 - February 2018). Together with this document we are publishing data from the best performing detector module which has a nuclear recoil threshold of 30.1eV. With this data-set we were able to set limits on the cross-section for spin-dependent and spin-independent elastic scattering of dark matter particles off nuclei at dark matter masses down to 160MeV/c$^2$. We publish the energies of all events after data selection as well as of all events within the acceptance region for dark-matter searches. In this document we describe how to use these data sets.

An improvement of both, the statistical and systematic uncertainty beyond the level achieved in Gallex is an essential prequisite for Gno. As major contributions to these errors are associated with the detection of the EC-decay of 71 Ge in miniaturized gas proportional counters, low temperature calorimetric detectors might provide an appealing alternative in a later phase of Gno. We show rst results achieved in measurements of the EC-decaying isotopes 71 Ge and 37 Ar with cryogenic calorimeters. 1 The GNO experiment Beyond any doubt, with its detection of pp-neutrinos Gallex 4] has provided key input for both, the establishment of what constitutes the current status of the solar neutrino puzzle and the rating of proposed explanatory attempts, cf. e.g. 1]. Gno (Gallium Neutrino Observatory) 6] is a continuation of Gallex, also using the capture reaction 71 Ga+ e ! 71 Ge+e ? followed by the low background counting of 71 Ge + e ? ! 71 Ga + e for neutrino detection. However, a substantial increase of both, the statistical and systematic accuracy beyond the level achieved in Gallex constitutes an essential prerequisite for Gno to reach its scientiic goals. Breaking down the present Gallex systematic error 2, 5] into individual contributions, one readily realizes that the counting process, i.e. the detection and recognition of the back-decay of the ultra-low 71 Ge activity produced by neutrino capture on 71 Ga, constitutes the issue to be primarily considered. More than 70% of the systematic uncertainty is associated with counting. Moreover, also the statistical uncertainty is dominated from the counting process. Its overall eeciency typically lies in the 65% to 75% range. The eeciency of the entire chemical process, in contrast, usually exceeds 95%. As in Gallex, in the rst phase of Gno miniatur-ized gas counters will be employed for 71 Ge detection. We have started to investigate the suitability of low temperature calorimeters, being developed at Munich since more than one decade, for detecting the 71 Ge decay in a future phase of Gno. 2 Cryogenic calorimeters for GNO Compared to conventional detectors, low temperature calorimeters usually exhibit a superior energy resolution , a fact which is particularly advantageous for low statistics experiments like Gno where any kind of background has to be suppressed rigorously. Obviously , the higher the energy resolution, the better is the signal-to-background ratio. In addition, any improvement in the energy resolution should also lead to a …