Search

The 1-ton-scale CUORE detector is made of 988 $${{{\hbox {TeO}}}}_2$$ crystals operated as cryogenic bolometers at a working temperature of $$\sim 10{{{\hbox { mK}}}}$$ . In order to provide the necessary cooling power at 4 K stage, a total of five pulse tube (PT) refrigerators are used. The PTs make the cryogenic system reliable and stable, but have the downside that mechanical vibrations at low frequencies (1.4 Hz and related harmonics) are injected into the experimental apparatus. An active noise cancellation technique has been developed in order to reduce such effect by taking advantage from the coherent interference of the pressure oscillations originated by the different PTs. The technique that will be presented consists in controlling the relative phases of the pressure waves running inside the CUORE PT lines, in order to achieve the lowest detector noise. By reducing the power of PT harmonics by a factor up to $$10^4$$ , it drastically suppresses the overall noise RMS on the CUORE detector. In the following, we demonstrate the reliability and effectiveness of the technique, showing that the optimization of the detector noise level is possible in different experimental conditions.

Despite the multiple and convincing evidence of the existence of dark matter (DM) in our Universe, its detection is one of the most pressing questions in particle physics. As of today, there is no unambiguous hint which could clarify the particle nature of DM. For these reasons, a huge experimental effort is ongoing, trying to realize experiments which can probe the particle properties of DM. In particular, direct search experiments are trying to cover the largest possible mass range, from a few MeVs up to TeVs. Particularly suited for the sub-GeV mass region are detectors containing light nuclei, which are sensitive to the scattering of light DM candidates. Among them, we investigate a carbon-based absorber to explore DM masses down to the MeV region. Thanks to their cryogenic properties (high Debye temperature and long-lived phonon modes), carbon-based materials operated as low temperature calorimeters could reach an energy threshold in the eV range and would allow for the exploration of new parameters of the DM–nucleus cross section. Despite several proposals, the possibility of operating a carbon-based cryogenic detector is yet to be demonstrated. In this contribution, the preliminary results obtained with a diamond absorber operated with a TES temperature sensor will be reported. The potential of such a detector in the current landscape of DM searches will also be illustrated.

CRESST is one of the most prominent direct detection experiments for dark matter particles with sub-GeV/c$$^2$$ 2 mass. One of the advantages of the CRESST experiment is the possibility to include a large variety of nuclides in the target material used to probe dark matter interactions. In this work, we discuss in particular the interactions of dark matter particles with protons and neutrons of $$^{6}$$ 6 Li. This is now possible thanks to new calculations on nuclear matrix elements of this specific isotope of Li. To show the potential of using this particular nuclide for probing dark matter interactions, we used the data collected previously by a CRESST prototype based on LiAlO$$_2$$ 2 and operated in an above ground test-facility at Max-Planck-Institut für Physik in Munich, Germany. In particular, the inclusion of $$^{6}$$ 6 Li in the limit calculation drastically improves the result obtained for spin-dependent interactions with neutrons in the whole mass range. The improvement is significant, greater than two order of magnitude for dark matter masses below 1 GeV/c$$^2$$ 2 , compared to the limit previously published with the same data.

In this work, a first cryogenic characterization of a scintillating $$\hbox {LiAlO}_{2}$$ LiAlO 2 single crystal is presented. The results achieved show that this material holds great potential as a target for direct dark matter search experiments. Three different detector modules obtained from one crystal grown at the Leibniz-Institut für Kristallzüchtung (IKZ) have been tested to study different properties at cryogenic temperatures. Firstly, two 2.8 g twin crystals were used to build different detector modules which were operated in an above-ground laboratory at the Max Planck Institute for Physics (MPP) in Munich, Germany. The first detector module was used to study the scintillation properties of $$\hbox {LiAlO}_{2}$$ LiAlO 2 at cryogenic temperatures. The second achieved an energy threshold of ($$213.02\pm 1.48$$ 213.02 ± 1.48 ) eV which allows setting a competitive limit on the spin-dependent dark matter particle-proton scattering cross section for dark matter particle masses between $$350\,\hbox {MeV/c}^{2}$$ 350 MeV/c 2 and $$1.50\,\hbox {GeV/c}^{2}$$ 1.50 GeV/c 2 . Secondly, a detector module with a 373 g $$\hbox {LiAlO}_{2}$$ LiAlO 2 crystal as the main absorber was tested in an underground facility at the Laboratori Nazionali del Gran Sasso (LNGS): from this measurement it was possible to determine the radiopurity of the crystal and study the feasibility of using this material as a neutron flux monitor for low-background experiments.

Coherent elastic neutrino–nucleus scattering ($$\hbox {CE}\nu \hbox {NS}$$CEνNS) offers a unique way to study neutrino properties and to search for new physics beyond the Standard Model. Nuclear reactors are promising sources to explore this process at low energies since they deliver large fluxes of anti-neutrinos with typical energies of a few MeV. In this paper, a new-generation experiment to study$$\hbox {CE}\nu \hbox {NS}$$CEνNSis described. The NUCLEUS experiment will use cryogenic detectors which feature an unprecedentedly low-energy threshold and a time response fast enough to be operated under above-ground conditions. Both sensitivity to low-energy nuclear recoils and a high event rate tolerance are stringent requirements to measuring$$\hbox {CE}\nu \hbox {NS}$$CEνNSof reactor anti-neutrinos. A new experimental site, the Very-Near-Site (VNS), at the Chooz nuclear power plant in France is described. The VNS is located between the two 4.25 $$\hbox {GW}_{\mathrm {th}}$$GWthreactor cores and matches the requirements of NUCLEUS. First results of on-site measurements of neutron and muon backgrounds, the expected dominant background contributions, are given. In this paper a preliminary experimental set-up with dedicated active and passive background reduction techniques and first background estimations are presented. Furthermore, the feasibility to operate the detectors in coincidence with an active muon veto at shallow overburden is studied. The paper concludes with a sensitivity study pointing out the physics potential of NUCLEUS at the Chooz nuclear power plant.

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 GeV/$$\hbox {c}^{2}$$c2) 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/$$\hbox {c}^{2}$$c2 although many motivated theoretical models having been proposed. The CRESST-III experiment employs scintillating $$\hbox {CaWO}_{{4}}$$CaWO4 crystals of $$\sim$$∼ 25 g as target material for dark matter interactions operated as cryogenic scintillating calorimeters at $$\sim$$∼ 10 mK. 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 $$\sim$$∼ 160 MeV/$$\hbox {c}^{2}$$c2. In this paper, an overview of the CRESST-III detectors and results will be presented.

CRESST is a direct dark matter search experiment, aiming for an observation of nuclear recoils induced by the interaction of dark matter particles with cryogenic scintillating calcium tungstate crystals. Instead of confining ourselves to standard spin-independent and spin-dependent searches, we re-analyze data from CRESST-II using a more general effective field theory (EFT) framework. On many of the EFT coupling constants, improved exclusion limits in the low-mass region (< 3-4 GeV) are presented., 7 pages, 9 figures

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 $$^7\hbox {Li}$$7Li is an ideal candidate to study spin-dependent dark matter interactions in the low mass region. Furthermore, $$^6\hbox {Li}$$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 $$\hbox {LiAlO}_2$$LiAlO2, a target crystal never used before in cryogenic experiments.

The CUPID-0 experiment searches for double beta decay using cryogenic calorimeters with double (heat and light) read-out. The detector, consisting of 24 ZnSe crystals 95 $$\%$$ enriched in $$^{82}$$ Se and two natural ZnSe crystals, started data-taking in 2017 at Laboratori Nazionali del Gran Sasso. We present the search for the neutrino-less double beta decay of $$^{82}$$ Se into the 0 $$_1^+$$ , 2 $$_1^+$$ and 2 $$_2^+$$ excited states of $$^{82}$$ Kr with an exposure of 5.74 kg $$\cdot $$ yr (2.24 $$\times $$ 10 $$^{25}$$ emitters $$\cdot $$ yr). We found no evidence of the decays and set the most stringent limits on the widths of these processes: $$\varGamma $$ ( $$^{82}$$ Se $$\rightarrow ^{82}$$ Kr $$_{0_1^+}$$ )8.55 $$\times $$ 10 $$^{-24}$$ yr $$^{-1}$$ , $$\varGamma $$ ( $$^{82}$$ Se $$\rightarrow ^{82}$$ Kr $$_{2_1^+}$$ ) $$\,{

The CUPID-0 detector hosted at the Laboratori Nazionali del Gran Sasso, Italy, is the first large array of enriched scintillating cryogenic detectors for the investigation of $$^{82}$$ Se neutrinoless double-beta decay ( $$0\nu \beta \beta $$ ). CUPID-0 aims at measuring a background index in the region of interest (RoI) for $$0\nu \beta \beta $$ at the level of 10 $$^{-3}$$ counts/(keV kg years), the lowest value ever measured using cryogenic detectors. CUPID-0 operates an array of Zn $$^{82}$$ Se scintillating bolometers coupled with bolometric light detectors, with a state of the art technology for background suppression and thorough protocols and procedures for the detector preparation and construction. In this paper, the different phases of the detector design and construction will be presented, from the material selection (for the absorber production) to the new and innovative detector structure. The successful construction of the detector lead to promising preliminary detector performance which is discussed here.

The CUORE-0 experiment searches for neutrinoless double beta decay in $$^{130}$$ Te. It consists of an array of 52 tellurium dioxide crystals, operated as bolometers at a temperature of 10 mK, with a total mass of about 39 kg of TeO $$_2$$ . CUORE-0 has been built to test the performance of the upcoming CUORE experiment and represents the largest $$^{130}$$ Te bolometric setup currently in operation. This experiment has been running in the Gran Sasso National Laboratory, Italy, since March 2013. We report the results of a search for neutrinoless double beta decay in 9.8 kg years $$^{130}$$ Te exposure, which allowed us to set the most stringent limit to date on this half-life. The performance of the detector in terms of background rate and energy resolution are also reported.

The CRESST-III experiment (Cryogenic Rare Events Search with Superconducting Thermometers), located at the underground facility Laboratori Nazionali del Gran Sasso in Italy, uses scintillating CaWO $$_4$$ crystals as cryogenic calorimeters to search for direct dark matter interactions in detectors. A large part of the parameter space for spin-independent scattering off nuclei remains untested for dark matter particles with masses below a few GeV/c $$^2$$ , despite many naturally motivated theoretical models for light dark matter particles. The CRESST-III detectors are designed to achieve the performance required to probe the low-mass region of the parameter space with a sensitivity never reached before. In this paper, new results on the performance and an overview of the CRESST-III detectors will be presented, emphasizing the results about the low-energy threshold for nuclear recoil of CRESST-III Phase 1 which started collecting data in August 2016.

The CRESST experiment uses cryogenic detectors based on transition-edge sensors to search for dark matter interactions. Each detector module consists of a scintillating CaWO $$_4$$ crystal and a silicon-on-sapphire (SOS) light detector which operate in coincidence (phonon-light technique). The 40-mm-diameter SOS disks (2 g mass) used in the data taking campaign of CRESST-II Phase 2 (2014–2016) reached absolute baseline resolutions of $$\sigma =$$ 4–7 eV. This is the best performance reported for cryogenic light detectors of this size. Newly developed silicon beaker light detectors (4 cm height, 4 cm diameter, 6 g mass), which cover a large fraction of the target crystal surface, have achieved a baseline resolution of $$\sigma = 5.8\,$$ eV. First results of further improved light detectors developed for the ongoing low-threshold CRESST-III experiment are presented.

Models for light dark matter particles with masses below 1 GeV/c $$^2$$ are a natural and well-motivated alternative to so-far unobserved weakly interacting massive particles. Gram-scale cryogenic calorimeters provide the required detector performance to detect these particles and extend the direct dark matter search program of CRESST. A prototype 0.5 g sapphire detector developed for the $$\nu $$ -cleus experiment has achieved an energy threshold of $$E_{th}=(19.7\pm 0.9)$$ eV. This is one order of magnitude lower than for previous devices and independent of the type of particle interaction. The result presented here is obtained in a setup above ground without significant shielding against ambient and cosmogenic radiation. Although operated in a high-background environment, the detector probes a new range of light-mass dark matter particles previously not accessible by direct searches. We report the first limit on the spin-independent dark matter particle-nucleon cross section for masses between 140 and 500 MeV/c $$^2$$ .