Results from the CUORE-0 experiment

The CUORE-0 experiment searched for neutrinoless double beta decay in 130Te using an array of 52 tellurium dioxide crystals, operated as bolometers at a temperature of 10 mK. It took data in the Gran Sasso National Laboratory (Italy) since March 2013 to March 2015. We present the results of a search for neutrinoless double beta decay in 9.8 kg-years 130Te exposure that allowed us to set the most stringent limit to date on this half-life. The performance of the detector in terms of background and energy resolution is also reported

CUORE and CUORE-0 experiments

Neutrino oscillation experiments proved that neutrinos have mass and this enhanced the interest in neutrinoless double-beta decay (0vßß). The observation of this very rare hypothetical decay would prove the leptonic number violation and would give us indications about neutrinos mass hierarchy and absolute mass scale. CUORE (Cryogenic Underground Observatory for Rare Events) is an array of 988 crystals of TeO2, for a total sensitive mass of 741 kg. Its goal is the observation of 0vßß of 130Te. The crystals, placed into the a dilution cryostat, are operated as bolometers at a temperature close to 10 mK. CUORE commissioning phase has been concluded recently in Gran Sasso National Laboratory, Italy, and data taking is expected to start in spring 2017. If target background rate is reached (0.01counts/day/keV/kg), the sensibility of CUORE will be, in five years of data taking, T1/21026years (1? CL). In order to test the quality of materials and optimize the construction procedures, the collaboration realized CUORE-0, that took data from spring of 2013 to summer 2015. Here, after a brief description of CUORE, I report its commissioning status and CUORE-0 results

Lowering the CUORE energy threshold

The Cryogenic Underground Observatory for Rare Events (CUORE) is a ton-scale double beta decay experiment based on TeO2 cryogenic bolometers and is currently in the last construction stage at the Gran Sasso National Laboratory (LNGS). Its primary goal is to observe neutrino-less double beta decay of 130Te, however thanks to the ultra-low background and large projected exposure it could also be suitable for other rare event searches, as the detection of solar axions, neutrinos from type II supernovae or direct detection of dark matter. The sensitivity for these searches will depend on the performance achieved at the low energy threshold. For this reason a trigger algorithm based on continuous data filtering has been developed which will allow lowering the threshold down to the few keV region. The new trigger has been tested in CUORE-0, a single-tower CUORE prototype consisting of 52 TeO2 bolometers and recently concluded, and here we present the results in terms of trigger efficiency, data selection and low-energy calibration

Status and prospects for CUORE

CUORE is a cryogenic detector consisting of 988 TeO2 crystals, 750 g each, and will be operated at a temperature of ~10 mK, to search for neutrinoless double beta decay (0¿ßß) of 130Te. The detector, in the final stages of construction at the Laboratori Nazionali del Gran Sasso (Italy), will start its operations in 2016. CUORE-0, its pilot experiment, has proven the feasibility of CUORE, demonstrating that the target background of 0.01 counts/keV/kg/y and the energy resolution of 5 keV are within reach. CUORE-0 also made the most precise measurement of the 2¿ßß decay. The expected sensitivity of CUORE to the 0¿ßß 130Te half-life is 9 •1025y, for 5 years of data taking. Here, we report the most recent results of CUORE-0, their implications for CUORE, and the current status of the CUORE experiment

The CUORE cryostat and its bolometric detector

CUORE is a cryogenic detector that will be operated at LNGS to search for neutrinoless double beta decay (0ββ) of 130Te. The detector installation was completed in summer 2016. Before the installation, several cold runs were done to test the cryogenic system performance. In the last cold run the base temperature of 6.3mK was reached in stable condition. CUORE-0, a CUORE prototype, has proven the feasibility of CUORE, demonstrating that the target background of 0.01 counts/keV/kg/y and the energy resolution of 5 keV are within reach

AlterBBN v2: A public code for calculating Big-Bang nucleosynthesis constraints in alternative cosmologies

International audienceWe present the version 2 of AlterBBN , an open public code for the calculation of the abundance of the elements from Big-Bang nucleosynthesis. It does not rely on any closed external library or program, aims at being user-friendly and allowing easy modifications, and provides a fast and reliable calculation of the Big-Bang nucleosynthesis constraints in the standard and alternative cosmologies

The CUORE slow monitoring systems

CUORE is a cryogenic experiment searching primarily for neutrinoless double decay in 130Te. It will begin data-taking operations in 2016. To monitor the cryostat and detector during commissioning and data taking, we have designed and developed Slow Monitoring systems. In addition to real-time systems using LabVIEW, we have an alarm, analysis, and archiving website that uses MongoDB, AngularJS, and Bootstrap software. These modern, state of the art software packages make the monitoring system transparent, easily maintainable, and accessible on many platforms including mobile devices

Status of the UCNτ\tau experiment

International audienceThe neutron is the simplest nuclear system that can be used to probe the structure of the weak interaction and search for physics beyond the standard model. Measurements of neutron lifetime and β-decay correlation coefficients with precisions of 0.02% and 0.1%, respectively, would allow for stringent constraints on new physics. The UCNτ experiment uses an asymmetric magneto-gravitational UCN trap with in situ counting of surviving neutrons to measure the neutron lifetime, τn = 877.7s (0.7s)stat (+0.4/−0.2s)sys. We discuss the recent result from UCNτ, the status of ongoing data collection and analysis, and the path toward a 0.25 s measurement of the neutron lifetime with UCNτ

Status of the UCNτ experiment

The neutron is the simplest nuclear system that can be used to probe the structure of the weak interaction and search for physics beyond the standard model. Measurements of neutron lifetime and β-decay correlation coefficients with precisions of 0.02% and 0.1%, respectively, would allow for stringent constraints on new physics. The UCNτ experiment uses an asymmetric magneto-gravitational UCN trap with in situ counting of surviving neutrons to measure the neutron lifetime, τn = 877.7s (0.7s)stat (+0.4/−0.2s)sys. We discuss the recent result from UCNτ, the status of ongoing data collection and analysis, and the path toward a 0.25 s measurement of the neutron lifetime with UCNτ

New result for the neutron β\beta-asymmetry parameter A0A_0 from UCNA

International audienceBackground: The neutron β-decay asymmetry parameter A0 defines the angular correlation between the spin of the neutron and the momentum of the emitted electron. Values for A0 permit an extraction of the ratio of the weak axial-vector to vector coupling constants, λ≡gA/gV, which under assumption of the conserved vector current hypothesis (gV=1) determines gA. Precise values for gA are important as a benchmark for lattice QCD calculations and as a test of the standard model. Purpose: The UCNA experiment, carried out at the Ultracold Neutron (UCN) source at the Los Alamos Neutron Science Center, was the first measurement of any neutron β-decay angular correlation performed with UCN. This article reports the most precise result for A0 obtained to date from the UCNA experiment, as a result of higher statistics and reduced key systematic uncertainties, including from the neutron polarization and the characterization of the electron detector response. Methods: UCN produced via the downscattering of moderated spallation neutrons in a solid deuterium crystal were polarized via transport through a 7 T polarizing magnet and a spin flipper, which permitted selection of either spin state. The UCN were then contained within a 3-m long cylindrical decay volume, situated along the central axis of a superconducting 1 T solenoidal spectrometer. With the neutron spins then oriented parallel or anti-parallel to the solenoidal field, an asymmetry in the numbers of emitted decay electrons detected in two electron detector packages located on both ends of the spectrometer permitted an extraction of A0. Results: The UCNA experiment reports a new 0.67% precision result for A0 of A0=−0.12054(44)stat(68)syst, which yields λ=gA/gV=−1.2783(22). Combination with the previous UCNA result and accounting for correlated systematic uncertainties produces A0=−0.12015(34)stat(63)syst and λ=gA/gV=−1.2772(20). Conclusions: This new result for A0 and gA/gV from the UCNA experiment has provided confirmation of the shift in values for gA/gV that has emerged in the published results from more recent experiments, which are in striking disagreement with the results from older experiments. Individual systematic corrections to the asymmetries in older experiments (published prior to 2002) were >10%, whereas those in the more recent ones (published after 2002) have been of the scale of <2%. The impact of these older results on the global average will be minimized should future measurements of A0 reach the 0.1% level of precision with central values near the most recent results