Searches for Light Dark Matter with the CRESST-III Experiment

Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) is a long-standing direct dark matter detection experiment with cryogenic detectors located at the underground facility Laboratori Nazionali del Gran Sasso in Italy. CRESST-III, the third generation of CRESST, was specifically designed to have a world-leading sensitivity for low-mass dark matter (DM) (less than 2\ua0GeV/c 2) to probe the spin-independent DM-nucleus cross section. At present, a large part of the parameter space for spin-independent scattering off nuclei remains untested for dark matter particles with masses below few GeV/c 2 although many motivated theoretical models having been proposed. The CRESST-III experiment employs scintillating CaWO 4 crystals of ∼ 25\ua0g as target material for dark matter interactions operated as cryogenic scintillating calorimeters at\ua0∼ 10\ua0mK. CRESST-III first data taking was successfully completed in 2018, achieving an unprecedented energy threshold for nuclear recoils. This result extended the present sensitivity to DM particles as light as ∼ 160\ua0MeV/c 2. In this paper, an overview of the CRESST-III detectors and results will be presented

Lithium-Containing Crystals for Light Dark Matter Search Experiments

In the current direct dark matter search landscape, the leading experiments in the sub-GeV mass region mostly rely on cryogenic techniques which employ crystalline targets. One attractive type of crystals for these experiments is those containing lithium, due to the fact that 7Li is an ideal candidate to study spin-dependent dark matter interactions in the low mass region. Furthermore, 6Li can absorb neutrons, a challenging background for dark matter experiments, through a distinctive signature which allows the monitoring of the neutron flux directly on site. In this work, we show the results obtained with three different detectors based on LiAlO 2, a target crystal never used before in cryogenic experiments

Local lattice relaxation around Tl substitutional impurities in a NaI(Tl) scintillator crystal

A Thallium (Tl) L3-edge x-ray absorption experiment was performed on a NaI(Tl) scintillation crystal at room temperature using fluorescence detection. The data analysis provides clear evidence for a ≃5 % average bond length expansion of the first shell I atoms surrounding the Tl impurities with respect to the Na-I crystallographic bond-length. Possible evidence for a slight expansion of the second and third shells is obtained. The data are compatible with a previous experiment performed at liquid nitrogen temperature considering thermal expansion. A critical review of existing theoretical predictions and density functional theory supercell calculations support present findings and suggest the opportunity to perform a high quality temperature dependent experiment

Scintillating bolometric technique for the neutrino-less double beta decay search: The LUCIFER/CUPID-0 experiment

CUPID is a proposed future tonne-scale bolometric neutrino-less double beta decay (0\u3bd\u3b2\u3b2) experiment to probe the Majorana nature of neutrinos and discover lepton number violation in the so-called inverted hierarchy region of the neutrino mass. In order to improve the sensitivity with respect to the current bolometric experiments, the source mass must be increased and the backgrounds in the region of interest must be dramatically reduced. The background suppression can be achieved discriminating \u3b2/\u3b3 against \u3b1 events by means of the different light yield produced in the interactions within a scintillating bolometer. The increase in the number of 0\u3bd\u3b2\u3b2 emitters demands for crystals grown with enriched material. LUCIFER/CUPID-0, the first demonstrator of CUPID, aims at running the first array of enriched scintillating Zn82Se bolometers (total mass of about 7\ua0kg of 82Se) with a background level as low as 10 123 counts/(keV\ua0kg\ua0y) in the energy region of interest. We present the results of the first measurement performed on three Zn82Se enriched scintillating bolometers operated deep underground in the Hall C of the Laboratori Nazionali del Gran Sasso

The LUCIFER/CUPID-0 demonstrator: Searching for the neutrinoless double-beta decay with Zn82Se scintillating bolometers

Future experiments on neutrinoless double beta-decay with the aim of exploring the inverted hierarchy region have to employ detectors with excellent energy resolution and zero background in the energy region of interest. Cryogenic scintillating bolometers turn out to be a suitable candidate since they offer particle discrimination: the dual channel detection of the heat and the scintillation light signal allows for particle identification. In particular such detectors permit for a suppression of \uce\ub1-induced backgrounds, a key-issue for next-generation tonne-scale bolometric experiments. We report on the progress and current status of the LUCIFER/CUPID-0 demonstrator, the first array of scintillating bolometers based on enriched Zn82Se crystals which is expected to start data taking in 2016 and the potential of this detection technique for a future tonne-scale bolometric experiment after CUORE

0\u3bd\u3b2\u3b2 decay: The CUPID-0 experiment

CUPID-0 is an array of 24 Zn82Se scintillating bolometers used to search for the 0\u3bd\u3b2\u3b2 decay of 82Se. It is the first large mass 0\u3bd\u3b2\u3b2 experiment exploiting a double read-out technique: the phonon signal to accurately measure particle energies and the light signal to reject the \u3b1-induced background. Its success might open the road to a next generation project of ton mass scale, CUPID. The array is in operation at Laboratori Nazionali del Gran Sasso since the beginning of 2017, in this paper we present the preliminary results obtained with an exposure of 10.45 kg\u2022 y