LUMINEU: a search for neutrinoless double beta decay based on ZnMoO 4 scintillating bolometers
Journal of Physics: Conference Series Institute of Physics 718:6 (2016) 062008
Abstract:
The LUMINEU is designed to investigate the possibility to search for neutrinoless double beta decay in 100Mo by means of a large array of scintillating bolometers based on ZnMoO4 crystals enriched in 100Mo. High energy resolution and relatively fast detectors, which are able to measure both the light and the heat generated upon the interaction of a particle in a crystal, are very promising for the recognition and rejection of background events. We present the LUMINEU concepts and the experimental results achieved aboveground and underground with large-mass natural and enriched crystals. The measured energy resolution, the α/β discrimination power and the radioactive internal contamination are all within the specifications for the projected final LUMINEU sensitivity. Simulations and preliminary results confirm that the LUMINEU technology can reach zero background in the region of interest (around 3 MeV) with exposures of the order of hundreds kgXyears, setting the bases for a next generation 0v2β decay experiment capable to explore the inverted hierarchy region of the neutrino mass pattern.New results on low-mass dark matter from the CRESST-II experiment
Journal of Physics: Conference Series Institute of Physics 718:4 (2016) 042044
Abstract:
The CRESST-II experiment is searching for dark matter particles via their elastic scattering off nuclei in a target material. The CRESST target consists of scintillating CaWO4 crystals which are operated as cryogenic calorimeters at millikelvin temperatures and read out by transition edge sensors. Each interaction in the CaWO4 target crystal produces a phonon signal and also a light signal that is measured by a secondary cryogenic calorimeter. The low energy thresholds of these detectors, combined with the presence of light nuclei in the target material, allow to probe the low-mass region of the parameter space for spin-independent dark matter-nucleon scattering with high sensitivity. In this contribution results from a blind analysis of one detector module operated in the latest measurement campaign are presented. An unprecedented sensitivity for the light dark matter has been obtained with 52kg live days and a threshold of 307eV for nuclear recoils, extending the reach of direct dark matter searches to the sub-GeV/c2 region.Constraints on low-mass WIMPs from the EDELWEISS-III dark matter search
Journal of Cosmology and Astroparticle Physics Insitute of Physics 2016:05 (2016) 019
Abstract:
We present the results of a search for elastic scattering from galactic dark matter in the form of Weakly Interacting Massive Particles (WIMPs) in the 4-30 GeV/c2 mass range. We make use of a 582 kg-day fiducial exposure from an array of 800 g Germanium bolometers equipped with a set of interleaved electrodes with full surface coverage. We searched specifically for ∼ 2.5-20 keV nuclear recoils inside the detector fiducial volume. As an illustration the number of observed events in the search for 5 (resp. 20) GeV/c2 WIMPs are 9 (resp. 4), compared to an expected background of 6.1 (resp. 1.4). A 90% CL limit of 4.3 × 10-40 cm2 (resp. 9.4 × 10-44 cm2) is set on the spin-independent WIMP-nucleon scattering cross-section for 5 (resp. 20) GeV/c2 WIMPs. This result represents a 41-fold improvement with respect to the previous EDELWEISS-II low-mass WIMP search for 7 GeV/c2 WIMPs. The derived constraint is in tension with hints of WIMP signals from some recent experiments, thus confirming results obtained with different detection techniques.In-situ study of light production and transport in phonon/light detector modules for dark matter search
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Elsevier (2016)
Abstract:
The CRESST experiment (Cryogenic Rare Event Search with Superconducting Thermometers) searches for dark matter via the phonon and light signals of elastic scattering processes in scintillating crystals. The discrimination between a possible dark matter signal and background is based on the light yield. We present a new method for evaluating the two characteristics of a phonon/light detector module that determine how much of the deposited energy is converted to scintillation light and how efficiently a module detects the produced light. In contrast to former approaches with dedicated setups, we developed a method which allows us to use data taken with the cryogenic setup, during a dark matter search phase. In this way, we accounted for the entire process that occurs in a detector module, and obtained information on the light emission of the crystal as well as information on the performance of the module (light transport and detection). We found that with the detectors operated in CRESST-II phase 1, about 20% of the produced scintillation light is detected. A part of the light is likely absorbed by creating meta-stable excitations in the scintillating crystals. The light not detected is not absorbed entirely, as an additional light detector can help to increase the fraction of detected light.Cryogenic phonon-scintillation detectors with PMT readout for rare event search experiments
Astroparticle Physics (2016)