Search

In the quest for direct dark matter detection, innovative approaches to lower the detection threshold and explore the sub-GeV mass range, have gained high relevance in the last decade. This study presents the pioneering use of Gallium Arsenide (GaAs) as a low-temperature calorimeter for probing dark matter-electron interactions within the DAREDEVIL (DARk-mattEr DEVIces for Low energy detection) project. Our experimental setup features a GaAs crystal at an ultralow temperature of 15 mK, coupled with a Neutron Transmutation Doped Germanium (NTD-Ge) thermal sensor for precise energy estimation. This configuration is the first step towards detecting single electrons scattered by dark matter particles within the GaAs crystal, to improve the sensitivity to low-mass dark matter candidates significantly. Taking advantage of the production of optical phonons in polar materials such as GaAs gives the possibility to study the scattering of sub-MeV dark matter. This paper presents a detailed analysis of the detector’s response, using a calibration spectrum using α particles and X-ray events. While the results do not meet the ambitious eV scale threshold yet, they establish a solid benchmark for assessing the detector’s current performance and sensitivity. This work not only highlights the detector’s potential but also sets the stage for future enhancements aimed at achieving the eV threshold, underscoring the promising direction of this detector technology. These findings demonstrate the feasibility of using GaAs as a cryogenic calorimeter and hence open new avenues for investigating the elusive nature of dark matter through innovative direct detection techniques. [ABSTRACT FROM AUTHOR]

The ACCESS (Array of Cryogenic Calorimeters to Evaluate Spectral Shapes) project aims to establish a novel technique to perform precision measurements of forbidden β -decays, which can serve as an important benchmark for nuclear physics calculations and represent a significant background in astroparticle physics experiments. ACCESS will operate a pilot array of cryogenic calorimeters based on natural and doped crystals containing β -emitting radionuclides. In this way, natural (e.g. 113 Cd and 115 In) and synthetic isotopes (e.g. 99 Tc) will be simultaneously measured with a common experimental technique. The array will also include further crystals optimised to disentangle the different background sources, thus reducing the systematic uncertainty. In this paper, we give an overview of the ACCESS research program, discussing a detector design study and promising results of 115 In. [ABSTRACT FROM AUTHOR]

Radioactivity was recently discovered as a source of decoherence and correlated errors for the real-world implementation of superconducting quantum processors. In this work, we measure levels of radioactivity present in a typical laboratory environment (from muons, neutrons, and γ -rays emitted by naturally occurring radioactive isotopes) and in the most commonly used materials for the assembly and operation of state-of-the-art superconducting qubits. We present a GEANT-4 based simulation to predict the rate of impacts and the amount of energy released in a qubit chip from each of the mentioned sources. We finally propose mitigation strategies for the operation of next-generation qubits in a radio-pure environment. [ABSTRACT FROM AUTHOR]

The COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) experiment aims at the detection of dark matter-induced recoils in sodium iodide (NaI) crystals operated as scintillating cryogenic calorimeters. The detection of both scintillation light and phonons allows performing an event-by-event signal to background discrimination, thus enhancing the sensitivity of the experiment. The choice of using NaI crystals is motivated by the goal of probing the long-standing DAMA/LIBRA results using the same target material. The construction of the experimental facility is foreseen to start by 2021 at the INFN Gran Sasso National Laboratory (LNGS) in Italy. It consists of a cryostat housing the target crystals shielded from the external radioactivity by a water tank acting, at the same time, as an active veto against cosmic ray-induced events. Taking into account both environmental radioactivity and intrinsic contamination of materials used for cryostat, shielding and infrastructure, we performed a careful background budget estimation. The goal is to evaluate the number of events that could mimic or interfere with signal detection while optimising the geometry of the experimental setup. In this paper we present the results of the detailed Monte Carlo simulations we performed, together with the final design of the setup that minimises the residual amount of background particles reaching the detector volume. [ABSTRACT FROM AUTHOR]

COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) is an experiment employing cryogenic calorimeters, dedicated to direct dark matter search in underground laboratories. Its goal is to cross-check the annual modulation signal the DAMA collaboration has been detecting for about 20 years (Bernabei et al. in Nucl Part Phys Proc 303–305:74–79, 2018. 10.1016/j.nuclphysbps.2019.03.015) and which has been ruled out by other experiments in certain dark matter scenarios. COSINUS can provide a model-independent test by the use of the same target material (NaI), with the additional chance of discriminating β / γ events from nuclear recoils on an event-by-event basis, by the application of a well-established temperature sensor technology developed within the CRESST collaboration. Each module is constituted by two detectors: the light detector, that is a silicon beaker equipped with a transition edge sensor (TES), and the phonon detector, a small cubic NaI crystal interfaced with a carrier of a harder material (e.g. CdWO 4 ), also instrumented with a TES. This technology had so far never been applied to NaI crystals because of several well-known obstacles, and COSINUS is the first experiment which succeeded in operating NaI crystals as cryogenic calorimeters. Here, we present the COSINUS project, describe the achievements and the challenges of the COSINUS prototype development and discuss the status and the perspectives of this NaI-based cryogenic frontier. [ABSTRACT FROM AUTHOR]

Non-equilibrium quasiparticles can deteriorate the performance of superconducting qubits by reducing their coherence. We are investigating a source of quasiparticles that has been too long neglected, namely radioactivity: cosmic rays, environmental radioactivity and contaminants in the materials can all generate phonons of energy sufficient to break Cooper pairs and thus increase the number of quasiparticles. In this contribution, we describe the status of the project and its perspectives. [ABSTRACT FROM AUTHOR]

We operated a PbMoO 4 scintillating cryogenic detector of 570 g, produced with archaeological lead. This compound features excellent low temperature characteristics in terms of light yield, 12 keV/MeV for β / γ interactions, and FWHM energy resolution, 11.7 keV at 2.6 MeV. Furthermore, the detector allows for an effective particle identification by means of pulse shape analysis on the heat read-out channel. The implementation of innovative techniques and procedures for the purification of raw materials used for the crystal growth, and the highly-pure archaeological Pb, allowed for the production of large volume high-quality crystal. The overall characteristics of the detector operated at cryogenic temperatures makes PbMoO 4 an excellent compound for neutrino physics applications, especially neutrinoless double-beta studies. [ABSTRACT FROM AUTHOR]

The Cryogenic Observatory for SIgnals seen in Next-generation Underground Searches (COSINUS) project aims to provide a model-independent cross-check of the long-standing DAMA/LIBRA claim on the observation of dark matter by using the same target material, but in a different experimental approach. Operating sodium iodide (NaI) scintillating crystals as low-temperature scintillating calorimeters has the distinct advantage of providing a lower energy threshold for nuclear recoil events as expected from dark matter particle interactions combined with particle discrimination. The dual readout of phonon and light allows us to provide background rejection on an event-by-event basis, a unique feature in comparison with other NaI-based dark matter searches. The manuscript discusses in detail the COSINUS detector concept and presents the results and performance parameters from our second prototype detector. [ABSTRACT FROM AUTHOR]

The detection of $$^{148}$$ Sm alpha decay with a precise measured half-life of $$\left( {6.4_{-1.3}^{+1.2} }\right) \times 10^{15}y$$ and a Q-value of 1987.3 $$\pm $$ 0.5 keV was achieved by a new experimental approach, where a conventional ZnWO $$_{4}$$ scintillating crystal doped with enriched $$^{148}$$ Sm isotope is operated as a cryogenic scintillating bolometer (phonon and light channel) at mK-temperatures. [ABSTRACT FROM AUTHOR]

Bolometric detectors are excellent devices for the investigation of neutrinoless double-beta decay ( $$0\nu \beta \beta $$ ). The observation of such decay would demonstrate the violation of lepton number, and at the same time, it would necessarily imply that neutrinos are Majorana particles. The sensitivity of cryogenic detectors based on TeO $$_2$$ is strongly limited by the $$\alpha $$ -background in the region of interest for the 0 $$\nu \beta \beta $$ of $$^{130}$$ Te. It has been demonstrated that particle identification in TeO $$_2$$ bolometers is possible, measuring the Cherenkov light produced by particle interactions. However, the discrimination efficiency is low, and an event-by-event identification with NTD-based light detectors has to be demonstrated. We will discuss the performance of a highly sensitive light detector exploiting the Neganov-Luke effect for signal amplification. The detector, being operated with NTD thermistor and coupled to a 750 g TeO $$_2$$ crystal, shows the ability for an event-by-event identification of electron/gamma and $$\alpha $$ particles. The obtained results demonstrate the possibility to enhance the sensitivity of TeO $$_2$$ -based 0 $$\nu \beta \beta $$ experiment to an unprecedented level. [ABSTRACT FROM AUTHOR]

CUORE, an array of 988 TeO2 bolometers, is about to be one of the most sensitive experiments searching for neutrinoless double-beta decay. Its sensitivity could be further improved by removing the background from α radioactivity. A few years ago it was pointed out that the signal fromβs can be tagged by detecting the emitted Cherenkov light, which is not produced by αs. In this paper we confirm this possibility. For the first time we measured the Cherenkov light emitted by a CUORE crystal, and found it to be 100 eV at the Q-value of the decay. To completely reject the α background, we compute that one needs light detectors with baseline noise below 20 eV RMS, a value which is 3–4 times smaller than the average noise of the bolometric light detectors we are using. We point out that an improved light detector technology must be developed to obtain TeO2 bolometric experiments able to probe the inverted hierarchy of neutrino masses. [ABSTRACT FROM AUTHOR]

We present the performances of a 330 g zinc molybdate (ZnMoO) crystal working as scintillating bolometer as a possible candidate for a next generation experiment to search for neutrinoless double beta decay of Mo. The energy resolution, evaluated at the 2615 keV γ-line of Tl, is 6.3 keV FWHM. The internal radioactive contaminations of the ZnMoO were evaluated as <6 μBq/kg (Th) and 27±6 μBq/kg (Ra). We also present the results of the α vs β/ γ discrimination, obtained through the scintillation light as well as through the study of the shape of the thermal signal alone. [ABSTRACT FROM AUTHOR]

Large-mass bolometers are today extensively used for dark matter and double beta decay searches, in both cases the ultimate experimental sensitivity is defined by the background level reached in such devices. The most common background sources and the techniques used for their identification and reduction are here reviewed, with a particular focus on double beta decay searches. The relevant role played by Monte Carlo simulations in this field is discussed. As a real case, the background optimization in the MiDBD experiment is described. [ABSTRACT FROM AUTHOR]

We present the results obtained in the development of scintillating double-beta-decay bolometers. Several Mo and Cd based crystals were tested with the bolometric technique. The scintillation light was measured through a second independent bolometer. A 140-g CdWO4 crystal was run in a 417-h live time measurement. Thanks to the scintillation light, the α background is easily discriminated, resulting in zero counts above the 2615-keV γ line of 208Tl. These results, combined with an extreme easy light detector operation, represent the first tangible proof demonstrating the feasibility of this kind of technique. [ABSTRACT FROM AUTHOR]

Neutrinos have recently provided us with the first tangible evidence of phenomena beyond the reach of our theory of the laws of particle physics, the remarkably predictive “Standard Model”. The positive observation of oscillations in atmospheric and in solar neutrinos gives new motivations for more sensitive searches. Unfortunately, the oscillation experiments can only provide data on the squared mass differences of the neutrino mass eigenstates, while the absolute scale can only be obtained from direct mass measurements, 3H end point measurements for example or, in the case of Majorana neutrinos, more sensitively by neutrinoless double beta decay. In fact, recently published constraints on the mixing angles of the neutrino mixing matrix make a strong case that if neutrinos are Majorana particles, there are many scenarios in which next-generation double beta decay experiments should be able to observe the phenomenon, trying to disentangle the mass scale of the neutrinos. The interest for next-generation double beta decay experiments is growing, for if the mass scale is below ∼ 0.2eV, double beta decay may be the only hope for measuring it. [ABSTRACT FROM AUTHOR]

Massive low temperature particle detectors and their possible impacts on searches for neutrinoless double beta decay (Oν-DBD) are presented and discussed. In particular, the experimental work of the Milano group is described. Special relevance is given to the present status of the search for Oν-DBD of 130Te and to the possible expansion of this experiment in the near future. The most recent results obtained by the Milano-Gran Sasso collaboration with a 20 bolometer array are presented. On the basis of these results, the construction of a 42 kg array consisting of 56 TeO2 bolometers (CUORICINO project), to extend the sensitivity of the present experiment, has been proposed. CUORICINO should represent also a feasibility test for a large array of 1000 bolometers (CUORE project) aiming at the search for neutrinoless Double Beta Decay, Cold Dark Matter and Solar Axions with extremely high sensitivity. [ABSTRACT FROM AUTHOR]

For the first time a Vanadium-based crystal was operated as cryogenic particle detector. The scintillating low temperature calorimetric technique was used for the characterization of a 22g YVO4 crystal aiming at the investigation of the 4-fold forbidden non-unique β- decay of 50V. The excellent bolometric performance of the compound together with high light output of the crystal make it an outstanding technique for the study of such elusive rate process. The internal radioactive contaminations of the crystal are also investigated showing that an improvement on the current status of material selection and purification are needed, 235/238U and 232Th are measured at the level of 28mBq/kg, 1.3 Bq/kg and 28m Bq/kg, respectively. In this work, we also discuss a future upgrade of the experimental set-up which may pave the road for the detection of the rare 50V β- decay. [ABSTRACT FROM AUTHOR]