Search

Diamond operated as a cryogenic calorimeter is an excellent target for direct detection of low-mass dark matter candidates. Following the realization of the first low-threshold cryogenic detector that uses diamond as absorber for astroparticle physics applications, we now present the resulting exclusion limits on the elastic spin-independent interaction cross-section of dark matter with diamond. We measured two 0.175 g CVD (Chemical Vapor Deposition) diamond samples, each instrumented with a Transition Edge Sensor made of Tungsten (W-TES). Thanks to the energy threshold of just 16.8 eV of one of the two detectors, we set exclusion limits on the elastic spin-independent interaction of dark matter particles with carbon nuclei down to dark matter masses as low as 0.122 GeV/c 2 . This work shows the scientific potential of cryogenic detectors made from diamond and lays the foundation for the use of this material as target for direct detection dark matter experiments. [ABSTRACT FROM AUTHOR]

CUPID will be a next generation experiment searching for the neutrinoless double β decay, whose discovery would establish the Majorana nature of the neutrino. Based on the experience achieved with the CUORE experiment, presently taking data at LNGS, CUPID aims to reach a background free environment by means of scintillating Li 2 100 MoO 4 crystals coupled to light detectors. Indeed, the simultaneous heat and light detection allows us to reject the dominant background of α particles, as proven by the CUPID-0 and CUPID-Mo demonstrators. In this work we present the results of the first test of the CUPID baseline module. In particular, we propose a new optimized detector structure and light sensors design to enhance the engineering and the light collection, respectively. We characterized the heat detectors, achieving an energy resolution of (5.9 ± 0.2) keV FWHM at the Q-value of 100 Mo (about 3034 keV). We studied the light collection of the baseline CUPID design with respect to an alternative configuration which features gravity-assisted light detectors' mounting. In both cases we obtained an improvement in the light collection with respect to past measures and we validated the particle identification capability of the detector, which ensures an α particle rejection higher than 99.9%, fully satisfying the requirements for CUPID. [ABSTRACT FROM AUTHOR]

RES-NOVA is a newly proposed experiment for detecting neutrinos from astrophysical sources, mainly Supernovae, using an array of cryogenic detectors made of PbWO 4 crystals produced from archaeological Pb. This unconventional material, characterized by intrinsic high radiopurity, enables low-background levels in the region of interest for the neutrino detection via Coherent Elastic neutrino-Nucleus Scattering (CE ν NS). This signal lies at the detector energy threshold, O(1 keV), and it is expected to be hidden by naturally occurring radioactive contaminants of the crystal absorber. Here, we present the results of a radiopurity assay on a 0.84 kg PbWO 4 crystal produced from archaeological Pb operated as a cryogenic detector. The crystal internal radioactive contaminations are: 232 Th <40 μ Bq/kg, 238 U <30 μ Bq/kg, 226 Ra 1.3 mBq/kg and 210 Pb 22.5 mBq/kg. We also present a background projection for the final experiment and possible mitigation strategies for further background suppression. The achieved results demonstrate the feasibility of realizing this new class of detectors. [ABSTRACT FROM AUTHOR]

CRESST is one of the most prominent direct detection experiments for dark matter particles with sub-GeV/c 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 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 and operated in an above ground test-facility at Max-Planck-Institut für Physik in Munich, Germany. In particular, the inclusion of 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 , compared to the limit previously published with the same data. [ABSTRACT FROM AUTHOR]

The CUORE experiment is a large bolometric array searching for the lepton number violating neutrino-less double beta decay ( 0 ν β β ) in the isotope 130 Te . In this work we present the latest results on two searches for the double beta decay (DBD) of 130 Te to the first 0 2 + excited state of 130 Xe : the 0 ν β β decay and the Standard Model-allowed two-neutrinos double beta decay ( 2 ν β β ). Both searches are based on a 372.5 kg × yr TeO 2 exposure. The de-excitation gamma rays emitted by the excited Xe nucleus in the final state yield a unique signature, which can be searched for with low background by studying coincident events in two or more bolometers. The closely packed arrangement of the CUORE crystals constitutes a significant advantage in this regard. The median limit setting sensitivities at 90% Credible Interval (C.I.) of the given searches were estimated as S 1 / 2 0 ν = 5.6 × 10 24 yr for the 0 ν β β decay and S 1 / 2 2 ν = 2.1 × 10 24 yr for the 2 ν β β decay. No significant evidence for either of the decay modes was observed and a Bayesian lower bound at 90 % C.I. on the decay half lives is obtained as: (T 1 / 2) 0 2 + 0 ν > 5.9 × 10 24 yr for the 0 ν β β mode and (T 1 / 2) 0 2 + 2 ν > 1.3 × 10 24 yr for the 2 ν β β mode. These represent the most stringent limits on the DBD of 130 Te to excited states and improve by a factor ∼ 5 the previous results on this process. [ABSTRACT FROM AUTHOR]

CUPID-0 is the first pilot experiment of CUPID, a next-generation project searching for neutrinoless double beta decay. In its first scientific run, CUPID-0 operated 26 ZnSe cryogenic calorimeters coupled to light detectors in the underground Laboratori Nazionali del Gran Sasso. In this work, we analyzed a ZnSe exposure of 11.34 kg year to search for the neutrinoless double beta decay of 70 Zn and for the neutrinoless positron-emitting electron capture of 64 Zn. We found no evidence for these decays and set 90 % credible interval limits of T 1 / 2 0 ν β β ( 70 Zn) > 1.6 10 21 year and T 1 / 2 0 ν E C β + ( 64 Zn) > 1.2 × 10 22 year, surpassing by more than one order of magnitude the previous experimental results (Belli et al. in J Phys G 38(11):115107, https://doi.org/10.1088/0954-3899/38/11/115107, 2011). [ABSTRACT FROM AUTHOR]

CUORE is a tonne-scale cryogenic detector operating at the Laboratori Nazionali del Gran Sasso (LNGS) that uses tellurium dioxide bolometers to search for neutrinoless double-beta decay of $$^{130}$$ Te. CUORE is also suitable to search for low energy rare events such as solar axions or WIMP scattering, thanks to its ultra-low background and large target mass. However, to conduct such sensitive searches requires improving the energy threshold to 10 keV. In this paper, we describe the analysis techniques developed for the low energy analysis of CUORE-like detectors, using the data acquired from November 2013 to March 2015 by CUORE-0, a single-tower prototype designed to validate the assembly procedure and new cleaning techniques of CUORE. We explain the energy threshold optimization, continuous monitoring of the trigger efficiency, data and event selection, and energy calibration at low energies in detail. We also present the low energy background spectrum of CUORE-0 below $$60 \, \mathrm {keV}$$ . Finally, we report the sensitivity of CUORE to WIMP annual modulation using the CUORE-0 energy threshold and background, as well as an estimate of the uncertainty on the nuclear quenching factor from nuclear recoils inCUORE-0. [ABSTRACT FROM AUTHOR]

Models for light dark matter particles with masses below 1GeV/c² 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 ν-cleus experiment has achieved an energy threshold of Eth = (19.7±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 accessiable by direct searches. We report the first limit on the spinindependent dark matter particle-nucleon cross section for masses between 140 and 500MeV/c². [ABSTRACT FROM AUTHOR]

Next-generation experiments searching for neutrinoless double-beta decay must be sensitive to a Majorana neutrino mass as low as 10 $$\mathrm {~meV}$$ . CUORE , an array of 988 TeO $$_2$$ bolometers being commissioned at Laboratori Nazionali del Gran Sasso, features an expected sensitivity of 50-130 $$\mathrm {~meV}$$ at 90 % C.L. The background is expected to be dominated by $$\alpha $$ radioactivity, and can be in principle removed by detecting the small amount of Cherenkov light emitted by the $$\beta $$ signal. The Cryogenic wide-Area Light Detectors with Excellent Resolution project aims at developing a small prototype experiment consisting of TeO $$_2$$ bolometers coupled to high-sensitivity light detectors based on kinetic inductance detectors. The R&D is focused on the light detectors in view of the implementation in a next-generation neutrinoless double-beta decay experiment. [ABSTRACT FROM AUTHOR]

The cryogenic dark matter experiment CRESST-II aims at the direct detection of WIMPs via elastic scattering off nuclei in scintillating CaWO $$_4$$ crystals. We present a new, highly improved, detector design installed in the current run of CRESST-II Phase 2 with an efficient active rejection of surface-alpha backgrounds. Using CaWO $$_4$$ sticks instead of metal clamps to hold the target crystal, a detector housing with fully-scintillating inner surface could be realized. The presented detector (TUM40) provides an excellent threshold of $${\sim }0.60$$ keV and a resolution of $$\sigma \,{\approx }\,0.090$$ keV (at 2.60 keV). With significantly reduced background levels, TUM40 sets stringent limits on the spin-independent WIMP-nucleon scattering cross section and probes a new region of parameter space for WIMP masses below 3 GeV/c $$^2$$ . In this paper, we discuss the novel detector design and the surface-alpha event rejection in detail. [ABSTRACT FROM AUTHOR]

CUORE-0 is a cryogenic detector that uses an array of tellurium dioxide bolometers to search for neutrinoless double-beta decay of $$\mathrm {^{130}Te}$$ . We present the first data analysis with $$7.1 \,\mathrm {kg\cdot y}$$ of total $$\mathrm {TeO_2}$$ exposure focusing on background measurements and energy resolution. The background rates in the neutrinoless double-beta decay region of interest (2.47 to $$2.57 \,\mathrm {MeV}$$ ) and in the $$\alpha $$ background-dominated region (2.70 to $$3.90\,\mathrm {MeV}$$ ) have been measured to be $${0.071\pm 0.011}$$ and $${0.019\pm 0.002}\,\mathrm {counts/(keV\cdot kg\cdot y)}$$ , respectively. The latter result represents a factor of 6 improvement from a predecessor experiment, Cuoricino. The results verify our understanding of the background sources in CUORE-0, which is the basis of extrapolations to the full CUORE detector. The obtained energy resolution (full width at half maximum) in the region of interest is $$5.7\,\mathrm {keV}$$ . Based on the measured background rate and energy resolution in the region of interest, CUORE-0 half-life sensitivity is expected to surpass the observed lower bound of Cuoricino with one year of live time. [ABSTRACT FROM AUTHOR]

Scintillating CaWO $$_4$$ single crystals are a promising multi-element target for rare-event searches and are currently used in the direct dark matter experiment CRESST (Cryogenic Rare Event Search with Superconducting Thermometers). The relative light output of different particle interactions in CaWO $$_4$$ is quantified by quenching factors (QFs). These are essential for an active background discrimination and the identification of a possible signal induced by weakly interacting massive particles (WIMPs). We present the first precise measurements of the QFs of O, Ca and W at mK temperatures by irradiating a cryogenic detector with a fast neutron beam. A clear energy dependence of the QF of O and, less pronounced, of Ca was observed for the first time. Furthermore, in CRESST neutron-calibration data a variation of the QFs among different CaWO $$_4$$ single crystals was found. For typical CRESST detectors the QFs in the region-of-interest (10-40 keV) are $$\hbox {QF}_\mathrm{O}^\mathrm{ROI}=(11.2\pm 0.5)$$ %, $$\hbox {QF}_\mathrm{Ca}^\mathrm{ROI}=(5.94\pm 0.49)$$ % and $$\hbox {QF}_\mathrm{W}^\mathrm{ROI}=(1.72\pm 0.21)$$ %. The latest CRESST data (run32) is reanalyzed using these fundamentally new results on light quenching in CaWO $$_4$$ having moderate influence on the WIMP analysis. Their relevance for future CRESST runs and for the clarification of previously published results of direct dark matter experiments is emphasised. [ABSTRACT FROM AUTHOR]

In this work, a first cryogenic characterization of a scintillating 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 LiAlO 2 at cryogenic temperatures. The second achieved an energy threshold of ( 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 MeV/c 2 and 1.50 GeV/c 2 . Secondly, a detector module with a 373 g 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. [ABSTRACT FROM AUTHOR]

The original version of this article unfortunately contains mistakes. [ABSTRACT FROM AUTHOR]

The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) dark matter search experiment aims for the detection of dark matter particles via elastic scattering off nuclei in CaWO 4 crystals. To understand the CRESST electromagnetic background due to the bulk contamination in the employed materials, a model based on Monte Carlo simulations was developed using the Geant4 simulation toolkit. The results of the simulation are applied to the TUM40 detector module of CRESST-II phase 2. We are able to explain up to (68 ± 16) % of the electromagnetic background in the energy range between 1 and 40 keV . [ABSTRACT FROM AUTHOR]

We report on a search for double beta decay of 130 Te to the first 0 + excited state of 130 Xe using a 9.8 kg · yr exposure of 130 Te collected with the CUORE-0 experiment. In this work we exploit different topologies of coincident events to search for both the neutrinoless and two-neutrino double beta decay modes. We find no evidence for either mode and place lower bounds on the half-lives: T 0 1 + 0 ν > 7.9 · 10 23 yr and T 0 1 + 2 ν > 2.4 · 10 23 yr ( 90 % CL ). Combining our results with those obtained by the CUORICINO experiment, we achieve the most stringent constraints available for these processes: T 0 1 + 0 ν > 1.4 · 10 24 yr and T 0 1 + 2 ν > 2.5 · 10 23 yr ( 90 % CL ). [ABSTRACT FROM AUTHOR]

In this work, we want to highlight the potential of lithium as a target for spin-dependent dark matter search in cryogenic experiments, with a special focus on the low-mass region of the parameter space. We operated a prototype detector module based on a Li 2 MoO 4 target crystal in an above-ground laboratory. Despite the high background environment, the detector sets a competitive limit on spin-dependent interactions of dark matter particles with protons and neutrons for masses between 0.8 GeV/c 2 and 1.5 GeV/c 2 . [ABSTRACT FROM AUTHOR]

CUPID-0 is the first large mass array of enriched Zn 82 Se scintillating low temperature calorimeters, operated at LNGS since 2017. During its first scientific runs, CUPID-0 collected an exposure of 9.95 kg year. Thanks to the excellent rejection of α particles, we attained the lowest background ever measured with thermal detectors in the energy region where we search for the signature of 82 Se neutrinoless double beta decay. In this work we develop a model to reconstruct the CUPID-0 background over the whole energy range of experimental data. We identify the background sources exploiting their distinctive signatures and we assess their extremely low contribution [down to ∼ 10 - 4 counts/(keV kg year)] in the region of interest for 82 Se neutrinoless double beta decay search. This result represents a crucial step towards the comprehension of the background in experiments based on scintillating calorimeters and in next generation projects such as CUPID. [ABSTRACT FROM AUTHOR]

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/c2) are presented. [ABSTRACT FROM AUTHOR]

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 82Se 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 82Se into the 01+, 21+ and 22+ excited states of 82Kr with an exposure of 5.74 kg·yr (2.24×1025 emitters·yr). We found no evidence of the decays and set the most stringent limits on the widths of these processes: Γ(82Se →82Kr01+)8.55×10-24 yr-1, Γ (82 Se →82 Kr 21+)<6.25×10-24 yr-1, Γ(82Se →82Kr22+)8.25×10-24 yr-1 (90% credible interval). [ABSTRACT FROM AUTHOR]

The suppression of spurious events in the region of interest for neutrinoless double beta decay will play a major role in next generation experiments. The background of detectors based on the technology of cryogenic calorimeters is expected to be dominated by α particles, that could be disentangled from double beta decay signals by exploiting the difference in the emission of the scintillation light. CUPID-0, an array of enriched Zn82Se scintillating calorimeters, is the first large mass demonstrator of this technology. The detector started data-taking in 2017 at the Laboratori Nazionali del Gran Sasso with the aim of proving that dual read-out of light and heat allows for an efficient suppression of the α background. In this paper we describe the software tools we developed for the analysis of scintillating calorimeters and we demonstrate that this technology allows to reach an unprecedented background for cryogenic calorimeters. [ABSTRACT FROM AUTHOR]

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 82Se neutrinoless double-beta decay (0νββ). CUPID-0 aims at measuring a background index in the region of interest (RoI) for 0νββ at the level of 10-3 counts/(keV kg years), the lowest value ever measured using cryogenic detectors. CUPID-0 operates an array of Zn82Se 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. [ABSTRACT FROM AUTHOR]