The DarkSide experiment aims to perform a background-free direct search for dark matter with a dual-phase argon TPC. The current phase of the experiment, DarkSide-50, is acquiring data at Laboratori ...Nazionali del Gran Sasso and produced the most sensitive limit on the WIMP-nucleon cross section ever obtained with a liquid argon target (2.0 × 10-44 cm2 for a WIMP mass of 100 GeV/c2). The future phase of the experiment will be a 20 t fiducial mass detector, designed to reach a sensitivity of ~1 × 10-47 cm2 (at 1 TeV/c2 WIMP mass) with a background-free exposure of 100 ty. Here, this work contains a discussion of the current status of the DarkSide-50 WIMP search and of the results which are more relevant for the construction of the future detector.
Precision measurements of solar neutrinos emitted by specific nuclear reaction chains in the Sun are of great interest for developing an improved understanding of star formation and evolution. Given ...the expected neutrino fluxes and known detection reactions, such measurements require detectors capable of collecting neutrino-electron scattering data in exposures on the order of 1 ktonne-yr, with good energy resolution and extremely low background. Two-phase liquid argon time projection chambers (LAr TPCs) are under development for direct Dark Matter WIMP searches, which possess very large sensitive mass, high scintillation light yield, good energy resolution, and good spatial resolution in all three cartesian directions. While enabling Dark Matter searches with sensitivity extending to the ``neutrino floor'' (given by the rate of nuclear recoil events from solar neutrino coherent scattering), such detectors could also enable precision measurements of solar neutrino fluxes using the neutrino-electron elastic scattering events.
163Ho Electron Capture (EC) decay has been studied since the last decade for measuring the neutrino mass. These studies have shown that the experimental energies of the EC decay lines are slightly ...different from the ones expected from theory. A true calorimetric measurement should be able to fix definitively the level energies. In 1996 (Phys. Lett. B 398 (1996) 415), the first calorimetric measurement of this spectrum was obtained by the Genoa group, which was able to resolve the doublet MI–MII and NI–NII at about 1800 and 400eV, respectively. The major drawback of this detector was the absorber, which had not been homogeneously made because the radioactive source was in dielectric form surrounded by the superconducting absorber. Here we present a new absorber for 163Ho experiment, which will be used in a new calorimetric measurement. It consists of a superconducting compound of yttrium, Y3Rh4Sn13, in which 163Ho is homogeneously spread.
The calorimetric measurement of neutrino mass in the sub-eV range is at present an appealing field of research. We are planning an experiment with higher energy resolution and better statistics than ...the pilot measurement we have done in the last years. Such an investigation requires an array of several detectors with energy resolution of a few eV and rhenium mass absorber of milligrams. We present the status of the development of the array's elements, which are made of composite microcalorimeters with Ag/Al TES grown on silicon substrate or directly on single rhenium crystal. (Author)
We examine the sensitivity of a large scale two-phase liquid argon detector to the directionality of the dark matter signal. This study was performed under the assumption that, above 50 keV of recoil ...energy, one can determine (with some resolution) the direction of the recoil nucleus without head-tail discrimination, as suggested by past studies that proposed to exploit the dependence of columnar recombination on the angle between the recoil nucleus direction and the electric field. In this paper we study the differential interaction recoil rate as a function of the recoil direction angle with respect to the zenith for a detector located at the Laboratori Nazionali del Gran Sasso and we determine its diurnal and seasonal modulation. Using a likelihood-ratio based approach we show that, with the angular information alone, 100 events are enough to reject the isotropic hypothesis at three standard deviation level. For an exposure of 100 tonne years this would correspond to a spin independent WIMP-nucleon cross section of about 10^-46 cm^2 at 200 GeV WIMP mass. The results presented in this paper provide strong motivation for the experimental determination of directional recoil effects in two-phase liquid argon detectors.
BEFS can be used for the study of microcrystalline structure by means of microcalorimetric detectors. To evaluate the precision and the reliability of this new method, we performed a comparison with ...EXAFS analysis. For this purpose the K-edge EXAFS measurement on rhenium metal have been done at the European Synchrotron Facility. The preliminary results indicate that BEFS analysis allows measurement of the interatomic distances with resolution of hundredths of Angstroms, comparable to EXAFS. (Author)
Precision measurements of solar neutrinos emitted by specific nuclear reaction chains in the Sun are of great interest for developing an improved understanding of star formation and evolution. Given ...the expected neutrino fluxes and known detection reactions, such measurements require detectors capable of collecting neutrino-electron scattering data in exposures on the order of 1 ktonne yr, with good energy resolution and extremely low background. Two-phase liquid argon time projection chambers (LAr TPCs) are under development for direct Dark Matter WIMP searches, which possess very large sensitive mass, high scintillation light yield, good energy resolution, and good spatial resolution in all three cartesian directions. While enabling Dark Matter searches with sensitivity extending to the "neutrino floor" (given by the rate of nuclear recoil events from solar neutrino coherent scattering), such detectors could also enable precision measurements of solar neutrino fluxes using the neutrino-electron elastic scattering events. Modeling results are presented for the cosmogenic and radiogenic backgrounds affecting solar neutrino detection in a 300 tonne (100 tonne fiducial) LAr TPC operating at LNGS depth (3,800 meters of water equivalent). The results show that such a detector could measure the CNO neutrino rate with ~15% precision, and significantly improve the precision of the 7Be and pep neutrino rates compared to the currently available results from the Borexino organic liquid scintillator detector.
