The CUORE experiment, a ton-scale cryogenic bolometer array, recently began operation at the Laboratori Nazionali del Gran Sasso in Italy. The array represents a significant advancement in this technology, and in this work we apply it for the first time to a high-sensitivity search for a lepton-number-violating process: ${}^{130}\mathrm{Te}$ neutrinoless double-beta decay. Examining a total ${\mathrm{TeO}}_2$ exposure of 86.3 kg yr, characterized by an effective energy resolution of $(7.7\pm 0.5)\mathrm{keV}$ FWHM and a background in the region of interest of $(0.014\pm 0.002)\mathrm{counts}/(\mathrm{keV}\mathrm{kg}\mathrm{yr})$, we find no evidence for neutrinoless double-beta decay. Including systematic uncertainties, we place a lower limit on the decay half-life of $T_{1/2}^{0\nu }({}^{130}\mathrm{Te})>1.3\times {10}^{25}\mathrm{yr}$ (90% C.L.); the median statistical sensitivity of this search is $7.0\times {10}^{24}\mathrm{yr}$. Combining this result with those of two earlier experiments, Cuoricino and CUORE-0, we find $T_{1/2}^{0\nu }({}^{130}\mathrm{Te})>1.5\times {10}^{25}\mathrm{yr}$ (90% C.L.), which is the most stringent limit to date on this decay. Interpreting this result as a limit on the effective Majorana neutrino mass, we find $m_{\beta \beta }<(110-520)\mathrm{meV}$, where the range reflects the nuclear matrix element estimates employed.

To account for the dark-matter content in our Universe, postinflationary scenarios predict for the QCD axion a mass in the range $(10–{10}^3)\mu \mathrm{eV}$. Searches with haloscope experiments in this mass range require the monitoring of resonant cavity modes with frequency above 5 GHz, where several experimental limitations occur due to linear amplifiers, small volumes, and low quality factors of copper resonant cavities. In this paper, we deal with the last issue, presenting the result of a search for galactic axions using a haloscope based on a $36{\mathrm{cm}}^3$ NbTi superconducting cavity. The cavity worked at $T=4\mathrm{K}$ in a 2 T magnetic field and exhibited a quality factor $Q_0=4.5\times {10}^5$ for the TM010 mode at 9 GHz. With such values of $Q$, the axion signal is significantly increased with respect to copper cavity haloscopes. Operating this setup, we set the limit $g_{a\gamma \gamma }<1.03\times {10}^{-12}{\mathrm{GeV}}^{-1}$ on the axion photon coupling for a mass of about $37\mu \mathrm{eV}$. A comprehensive study of the NbTi cavity at different magnetic fields, temperatures, and frequencies is also presented.

A ferromagnetic axion haloscope searches for dark matter in the form of axions by exploiting their interaction with electronic spins. It is composed of an axion-to-electromagnetic field transducer coupled to a sensitive rf detector. The former is a photon-magnon hybrid system, and the latter is based on a quantum-limited Josephson parametric amplifier. The hybrid system consists of ten 2.1 mm diameter yttrium iron garnet spheres coupled to a single microwave cavity mode by means of a static magnetic field. Our setup is the most sensitive rf spin magnetometer ever realized. The minimum detectable field is $5.5\times {10}^{-19}\mathrm{T}$ with 9 h integration time, corresponding to a limit on the axion-electron coupling constant $g_{aee}\le 1.7\times {10}^{-11}$ at 95% C.L. The scientific run of our haloscope resulted in the best limit on dark matter axions to electron coupling constant in a frequency span of about 120 MHz, corresponding to the axion-mass range $42.4–43.1\mu \mathrm{eV}$. This is also the first apparatus to perform a wide axion-mass scanning by only changing the static magnetic field.

A haloscope of the QUAX–$a\gamma$ experiment composed of an oxygen-free high thermal conductivity-Cu cavity inside an 8.1 T magnet and cooled to $\sim 200\mathrm{mK}$ is put in operation for the search of galactic axion with mass $m_a\simeq 43\mu \mathrm{eV}$. The power emitted by the resonant cavity is amplified with a Josephson parametric amplifier whose noise fluctuations are at the standard quantum limit. With the data collected in about 1 h at the cavity frequency ${\nu }_c=10.40176\mathrm{GHz}$, the experiment reaches the sensitivity necessary for the detection of galactic QCD-axion, setting the 90% confidence level limit to the axion-photon coupling $g_{a\gamma \gamma }<0.766\times {10}^{-13}{\mathrm{GeV}}^{-1}$.

The Cryogenic Underground Observatory for Rare Events (CUORE) is designed to search for neutrinoless double beta decay of $$^{130}$$ Te with an array of 98

Neutrinoless double-beta (0νββ) decay is a hypothesized lepton-number-violating process that offers the only known means of asserting the possible Majorana nature of neutrino mass. The Cryogenic Underground Observatory for Rare Events (CUORE) is an upcoming experiment designed to search for 0νββdecay of¹³⁰Te using an array of 988 TeO₂crystal bolometers operated at 10 mK. The detector will contain 206 kg of¹³⁰Te and have an average energy resolution of 5 keV; the projected 0νββdecay half-life sensitivity after five years of livetime is 1.6 × 10²⁶ y at 1σ(9.5 × 10²⁵ y at the 90% confidence level), which corresponds to an upper limit on the effective Majorana mass in the range 40–100 meV (50–130 meV). In this paper, we review the experimental techniques used in CUORE as well as its current status and anticipated physics reach.