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Many of the most sensitive physics experiments searching for rare events, like neutrinoless double beta ( 0 ν β β ) decay, coherent elastic neutrino nucleus scattering and dark matter interactions, rely on cryogenic macro-calorimeters operating at the mK-scale. Located underground at the Gran Sasso National Laboratory (LNGS), in central Italy, CUORE (Cryogenic Underground Observatory for Rare Events) is one of the leading experiments for the search of 0 ν β β decay, implementing the low-temperature calorimetric technology. We present a novel multi-device analysis to correlate environmental phenomena with the low-frequency noise of low-temperature calorimeters. Indeed, the correlation of marine and seismic data with data from a couple of CUORE detectors indicates that cryogenic detectors are sensitive not only to intense vibrations generated by earthquakes, but also to the much fainter vibrations induced by marine microseisms in the Mediterranean Sea due to the motion of sea waves. Proving that cryogenic macro-calorimeters are sensitive to such environmental sources of noise opens the possibility of studying their impact on the detectors physics-case sensitivity. Moreover, this study could pave the road for technology developments dedicated to the mitigation of the noise induced by marine microseisms, from which the entire community of cryogenic calorimeters can benefit.

The possibility that neutrinos may be their own antiparticles, unique among the known fundamental particles, arises from the symmetric theory of fermions proposed by Ettore Majorana in 1937 1 . Given the profound consequences of such Majorana neutrinos, among which is a potential explanation for the matter–antimatter asymmetry of the universe via leptogenesis 2 , the Majorana nature of neutrinos commands intense experimental scrutiny globally; one of the primary experimental probes is neutrinoless double beta (0 νββ ) decay. Here we show results from the search for 0 νββ decay of 130 Te, using the latest advanced cryogenic calorimeters with the CUORE experiment 3 . CUORE, operating just 10 millikelvin above absolute zero, has pushed the state of the art on three frontiers: the sheer mass held at such ultralow temperatures, operational longevity, and the low levels of ionizing radiation emanating from the cryogenic infrastructure. We find no evidence for 0 νββ decay and set a lower bound of the process half-life as 2.2 × 10 25  years at a 90 per cent credibility interval. We discuss potential applications of the advances made with CUORE to other fields such as direct dark matter, neutrino and nuclear physics searches and large-scale quantum computing, which can benefit from sustained operation of large payloads in a low-radioactivity, ultralow-temperature cryogenic environment. The CUORE experiment finds no evidence for neutrinoless double beta decay after operating a large cryogenic TeO 2 calorimeter stably for several years in an extreme low-radiation environment at a temperature of 10 millikelvin.

Localization and modeling of radioactive contaminations is a challenge that ultra-low background experiments are constantly facing. These are fundamental steps both to extract scientific results and to further reduce the background of the detectors. Here we present an innovative technique based on the analysis of α-α delayed coincidences in 232Th and 238U decay chains, developed to investigate the contaminations of the ZnSe crystals in the CUPID-0 experiment. This method allows to disentangle surface and bulk contaminations of the detectors relying on the different probability to tag delayed coincidences as function of the α decay position.

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 \\[\\alpha \\] 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 Zn\\[^{82}\\]Se 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 \\[\\alpha \\] 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.

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^+}\\])\\[\\,{<}\\,6.25 \\,{\\times }\\,10^{-24}\\] yr\\[^{-1}\\], \\[\\varGamma \\](\\[^{82}\\]Se \\[\\rightarrow ^{82}\\]Kr\\[_{2_2^+}\\])8.25\\[\\times \\]10\\[^{-24}\\] yr\\[^{-1}\\] (90\\[\\%\\] credible interval).

The 1-ton-scale CUORE detector is made of 988 TeO 2 crystals operated as cryogenic bolometers at a working temperature of ∼ 10 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.

New IRAM KID array 2 (NIKA2) is a camera dedicated to millimeter-wave astronomy based upon kilopixel arrays of kinetic inductance detectors [ 1 ] (KID). The pathfinder instrument, NIKA [ 2 ], has already shown state-of-the-art detector performance. NIKA2 builds upon this experience but goes one step further, increasing the total pixel count by a factor ∼ 10 while maintaining the same per pixel performance. For the next decade, this camera will be the resident photometric instrument of the Institut de Radio Astronomie Millimetrique (IRAM) 30 m telescopes in Sierra Nevada (Spain). In this paper, we give an overview of the main components of NIKA2 and describe the achieved detector performance. The camera has been permanently installed at the IRAM 30 m telescope in October 2015. It will be made accessible to the scientific community at the end of 2016, after a 1-year commissioning period. When this happens, NIKA2 will become a fundamental tool for astronomers worldwide.

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/\\[c^2\\]) are presented.

RES-NOVA is a newly proposed experiment for detecting neutrinos from astrophysical sources, mainly Supernovae, using an array of cryogenic detectors made of PbWO4 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 (CEνNS). 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 PbWO4 crystal produced from archaeological Pb operated as a cryogenic detector. The crystal internal radioactive contaminations are: 232Th <40 μBq/kg, 238U <30 μBq/kg, 226Ra 1.3 mBq/kg and 210Pb 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.

We report on the development of thermal kinetic inductance detectors (TKIDs) suitable to perform X-ray spectroscopy measurements. The aim is to implement MKIDs sensors working in thermal quasi-equilibrium mode to detect X-ray photons as pure calorimeters. The thermal mode is a variation on the MKID classical way of operation that has generated interest in recent years. TKIDs can offer the MKIDs inherent multiplexibility in the frequency domain, a high spatial resolution comparable with CCDs, and an energy resolution theoretically limited only by thermodynamic fluctuations across the thermal weak links. Microresonators are built in Ti/TiN multilayer technology with the inductive part thermally coupled with a metal absorber on a suspended SiN membrane, to avoid escape of phonons from the film to the substrate. The mid-term goal is to optimize the single-pixel design in terms of superconducting critical temperatures, internal quality factors, kinetic inductance and spectral energy resolution. The final goal is to realize a demonstrator array for a next generation thousand pixels X-ray spectrometer. In this contribution, the status of the project after one year of developments is reported, with detailed reference to the microresonators design and simulations and to the fabrication process.