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In the core of the Sun, energy is released through sequences of nuclear reactions that convert hydrogen into helium. The primary reaction is thought to be the fusion of two protons with the emission of a low-energy neutrino. These so-called pp neutrinos constitute nearly the entirety of the solar neutrino flux, vastly outnumbering those emitted in the reactions that follow. Although solar neutrinos from secondary processes have been observed, proving the nuclear origin of the Sun’s energy and contributing to the discovery of neutrino oscillations, those from proton–proton fusion have hitherto eluded direct detection. Here we report spectral observations of pp neutrinos, demonstrating that about 99 per cent of the power of the Sun, 3.84 × 10 33 ergs per second, is generated by the proton–proton fusion process. Spectral observations of the low-energy neutrinos produced by proton–proton fusion in the Sun demonstrate that about 99 per cent of the Sun’s power is generated by this process. Sun's elusive pp neutrinos tracked down The Sun's energy output derives from a sequence of nuclear reactions that converts hydrogen into helium, most of it from the fusion of two protons (the proton–proton or pp reaction) accompanied by the release of a low-energy neutrino. These neutrinos have proved elusive: only solar neutrinos from secondary reactions had been directly observed. But here the Borexino collaboration reports observations of the pp neutrinos themselves, so providing a direct view of the principal fusion process that powers the Sun.

We report on the measurement of the two-neutrino double-beta decay half-life of [Formula omitted]Te with the CUORE-0 detector. From an exposure of 33.4 kg year of TeO [Formula omitted], the half-life is determined to be [Formula omitted] = [8.2 ± 0.2 (stat.) ± 0.6 (syst.)] [Formula omitted] 10 [Formula omitted] year. This result is obtained after a detailed reconstruction of the sources responsible for the CUORE-0 counting rate, with a specific study of those contributing to the [Formula omitted]Te neutrinoless double-beta decay region of interest.

We report on the measurement of the two-neutrino double-beta decay half-life of 130 Te with the CUORE-0 detector. From an exposure of 33.4 kg year of TeO 2 , the half-life is determined to be T 1 / 2 2 ν = [8.2 ± 0.2 (stat.) ± 0.6 (syst.)] × 10 20  year. This result is obtained after a detailed reconstruction of the sources responsible for the CUORE-0 counting rate, with a specific study of those contributing to the 130 Te neutrinoless double-beta decay region of interest.

A bstract The very low radioactive background of the Borexino detector, its large size, and the well proved capability to detect both low energy electron neutrinos and antineutrinos make an ideal case for the study of short distance neutrino oscillations with artificial sources at Gran Sasso. This paper describes the possible layouts of 51 Cr ( ν e ) and 144 Ce- 144 Pr source experiments in Borexino and shows the expected sensitivity to eV mass sterile neutrinos for three possible different phases of the experiment. Expected results on neutrino magnetic moment, electroweak mixing angle, and couplings to axial and vector currents are shown too.

The Cryogenic Underground Observatory for Rare Events (CUORE) is designed to search for neutrinoless double beta decay of 130 Te with an array of 988 TeO 2  bolometers operating at temperatures around 10 mK. The experiment is currently being commissioned in Hall A of Laboratori Nazionali del Gran Sasso, Italy. The goal of CUORE is to reach a 90% C.L. exclusion sensitivity on the 130 Te decay half-life of 9 × 10 25 years after 5 years of data taking. The main issue to be addressed to accomplish this aim is the rate of background events in the region of interest, which must not be higher than 10 - 2  counts/keV/kg/year. We developed a detailed Monte Carlo simulation, based on results from a campaign of material screening, radioassays, and bolometric measurements, to evaluate the expected background. This was used over the years to guide the construction strategies of the experiment and we use it here to project a background model for CUORE. In this paper we report the results of our study and our expectations for the background rate in the energy region where the peak signature of neutrinoless double beta decay of 130 Te is expected.

We report a study of the CUORE sensitivity to neutrinoless double beta ( 0 ν β β ) decay. We used a Bayesian analysis based on a toy Monte Carlo (MC) approach to extract the exclusion sensitivity to the 0 ν β β decay half-life ( T 1 / 2 0 ν ) at 90 %  credibility interval (CI) – i.e. the interval containing the true value of T 1 / 2 0 ν with 90 % probability – and the 3 σ discovery sensitivity. We consider various background levels and energy resolutions, and describe the influence of the data division in subsets with different background levels. If the background level and the energy resolution meet the expectation, CUORE will reach a 90 %  CI exclusion sensitivity of 2 · 10 25  year with 3 months, and 9 · 10 25  year with 5 years of live time. Under the same conditions, the discovery sensitivity after 3 months and 5 years will be 7 · 10 24  year and 4 · 10 25  year, respectively.

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 _0^+_1>7.9 10^23 yr\\] and \\[T^2 _0^+_1>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 _0^+_1>1.4 10^24 yr\\] and \\[T^2 _0^+_1>2.5 10^23 yr\\] (\\[90\\%\\, CL\\]).

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 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.

We report a study of the CUORE sensitivity to neutrinoless double beta (0νββ) decay. We used a Bayesian analysis based on a toy Monte Carlo (MC) approach to extract the exclusion sensitivity to the 0νββ decay half-life (T1/20ν) at 90% credibility interval (CI) – i.e. the interval containing the true value of T1/20ν with 90% probability – and the 3σ discovery sensitivity. We consider various background levels and energy resolutions, and describe the influence of the data division in subsets with different background levels. If the background level and the energy resolution meet the expectation, CUORE will reach a 90% CI exclusion sensitivity of 2·1025 year with 3 months, and 9·1025 year with 5 years of live time. Under the same conditions, the discovery sensitivity after 3 months and 5 years will be 7·1024 year and 4·1025 year, respectively.