The CUORE Cryostat: A 1-Ton Scale Setup for Bolometric Detectors

The cryogenic underground observatory for rare events (CUORE) is a 1-ton scale bolometric experiment whose detector consists of an array of 988 TeO2 crystals arranged in a cylindrical compact structure of 19 towers. This will be the largest bolometric mass ever operated. The experiment will work at a temperature around or below 10 mK. CUORE cryostat consists of a cryogen-free system based on pulse tubes and a custom high power dilution refrigerator, designed to match these specifications. The cryostat has been commissioned in 2014 at the Gran Sasso National Laboratories and reached a record temperature of 6 mK on a cubic meter scale. In this paper, we present results of CUORE commissioning runs. Details on the thermal characteristics and cryogenic performances of the system will be also given.Comment: 7 pages, 2 figures, LTD16 conference proceedin

A single mutation in cyclodextrin glycosyltransferase from Paenibacillus barengoltzii changes cyclodextrin and maltooligosaccharides production

Cyclodextrin glycosyltransferases (CGTases) are bacterial enzymes that catalyze starch conversion into cyclodextrins, which have several biotechnological applications including solubilization of hydrophobic compounds, masking of unpleasant odors and flavors in pharmaceutical preparations, and removal of cholesterol from food. Additionally, CGTases produce maltooligosaccharides, which are linear molecules with potential benefits for human health. Current research efforts are concentrated in the development of engineered enzymes with improved yield and/or particular product specificity. In this work, we analyzed the role of four residues of the CGTase from Paenibacillus barengoltzii as determinants of product specificity. Single mutations were introduced in the CGTase-encoding gene to obtain mutants A137V, A144V, L280A and M329I and the activity of recombinant proteins was evaluated. The residue at position 137 proved to be relevant for CGTase activity. Molecular dynamics studies demonstrated additionally that mutation A137V produces a perturbation in the catalytic site of the CGTase, which correlates with a 10-fold reduction in its catalytic efficiency. Moreover, this mutant showed increased production of maltooligosaccharides with a high degree of polymerization, mostly maltopentaose to maltoheptaose. Our results highlight the role of residue 137 as a determinant of product specificity in this CGTase and may be applied to the rational design of saccharide-producing enzymes.Fil: Castillo, Julieta de Las Mercedes. Universidad Nacional de Luján. Departamento de Ciencias Básicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Caminata Landriel, Soledad. Universidad Nacional de Luján. Departamento de Ciencias Básicas; ArgentinaFil: Sànchez Costa, M.. Centro de Biología Molecular "Severo Ochoa"; EspañaFil: Taboga, Oscar Alberto. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Berenguer, J.. Centro de Biología Molecular "Severo Ochoa"; EspañaFil: Hidalgo, A.. Centro de Biología Molecular "Severo Ochoa"; EspañaFil: Ferrarotti, Susana Alicia. Universidad Nacional de Luján. Departamento de Ciencias Básicas; ArgentinaFil: Costa, Hernán. Universidad Nacional de Luján. Departamento de Ciencias Básicas; Argentina. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentin

R&D project for neutrinoless double beta decay in Borexino

Since the proposal of the Borexino project in the early nineties, the idea to perform a neutrinoless double beta decay experiment with 136Xe dissolved in the scintillator was considered. The beautiful results obtained by the Borexino experiment, which achieved a purity far exceeding design goals, and a new concept for dissolving large quantities of xenon in the scintillator by increasing its pressure make this possibility even more interesting for a new-generation experiment in the next decade. We present the ongoing R&D studies to look for neutrinoless double beta decay using liquid scintillators, discussing the optical properties of the Borexino scintillator when xenon is dissolved in large quantity and with high pressure

The CUORE cryostat: an infrastructure for rare event searches at millikelvin temperatures

The CUORE experiment is the world's largest bolometric experiment. The detector consists of an array of 988 TeO2 crystals, for a total mass of 742 kg. CUORE is presently taking data at the Laboratori Nazionali del Gran Sasso, Italy, searching for the neutrinoless double beta decay of 130Te. A large custom cryogen-free cryostat allows reaching and maintaining a base temperature of about 10 mK, required for the optimal operation of the detector. This apparatus has been designed in order to achieve a low noise environment, with minimal contribution to the radioactive background for the experiment. In this paper, we present an overview of the CUORE cryostat, together with a description of all its sub-systems, focusing on the solutions identified to satisfy the stringent requirements. We briefly illustrate the various phases of the cryostat commissioning and highlight the relevant steps and milestones achieved each time. Finally, we describe the successful cooldown of CUORE

Solar neutrino with Borexino: results and perspectives

Borexino is a unique detector able to perform measurement of solar neutrinos fluxes in the energy region around 1 MeV or below due to its low level of radioactive background. It was constructed at the LNGS underground laboratory with a goal of solar $^{7}$Be neutrino flux measurement with 5\% precision. The goal has been successfully achieved marking the end of the first stage of the experiment. A number of other important measurements of solar neutrino fluxes have been performed during the first stage. Recently the collaboration conducted successful liquid scintillator repurification campaign aiming to reduce main contaminants in the sub-MeV energy range. With the new levels of radiopurity Borexino can improve existing and challenge a number of new measurements including: improvement of the results on the Solar and terrestrial neutrino fluxes measurements; measurement of pp and CNO solar neutrino fluxes; search for non-standard interactions of neutrino; study of the neutrino oscillations on the short baseline with an artificial neutrino source (search for sterile neutrino) in context of SOX project.Comment: 15 pages, 4 figure

Spectroscopy of geo-neutrinos from 2056 days of Borexino data

We report an improved geo-neutrino measurement with Borexino from 2056 days of data taking. The present exposure is $(5.5\pm0.3)\times10^{31}$ proton$\times$yr. Assuming a chondritic Th/U mass ratio of 3.9, we obtain $23.7 ^{+6.5}_{-5.7} (stat) ^{+0.9}_{-0.6} (sys)$ geo-neutrino events. The null observation of geo-neutrinos with Borexino alone has a probability of $3.6 \times 10^{-9}$ (5.9$\sigma$). A geo-neutrino signal from the mantle is obtained at 98\% C.L. The radiogenic heat production for U and Th from the present best-fit result is restricted to the range 23-36 TW, taking into account the uncertainty on the distribution of heat producing elements inside the Earth.Comment: 4 pages, 4 figure

The Main Results of the Borexino Experiment

The main physical results on the registration of solar neutrinos and the search for rare processes obtained by the Borexino collaboration to date are presented.Comment: 8 pages, 8 figgures, To be published as Proceedings of the Third Annual Large Hadron Collider Physics Conference, St. Petersburg, Russia, 201

Measurement of neutrino flux from the primary proton--proton fusion process in the Sun with Borexino detector

Neutrino produced in a chain of nuclear reactions in the Sun starting from the fusion of two protons, for the first time has been detected in a real-time detector in spectrometric mode. The unique properties of the Borexino detector provided an oppurtunity to disentangle pp-neutrino spectrum from the background components. A comparison of the total neutrino flux from the Sun with Solar luminosity in photons provides a test of the stability of the Sun on the 10$^{5}$ years time scale, and sets a strong limit on the power production in the unknown energy sources in the Sun of no more than 4\% of the total energy production at 90\% C.L.Comment: 15 pages, 2 tables, 3 figure

CUORE-0 results and prospects for the CUORE experiment

With 741 kg of TeO2 crystals and an excellent energy resolution of 5 keV (0.2%) at the region of interest, the CUORE (Cryogenic Underground Observatory for Rare Events) experiment aims at searching for neutrinoless double beta decay of 130Te with unprecedented sensitivity. Expected to start data taking in 2015, CUORE is currently in an advanced construction phase at LNGS. CUORE projected neutrinoless double beta decay half-life sensitivity is 1.6E26 y at 1 sigma (9.5E25 y at the 90% confidence level), in five years of live time, corresponding to an upper limit on the effective Majorana mass in the range 40-100 meV (50-130 meV). Further background rejection with auxiliary bolometric detectors could improve CUORE sensitivity and competitiveness of bolometric detectors towards a full analysis of the inverted neutrino mass hierarchy. CUORE-0 was built to test and demonstrate the performance of the upcoming CUORE experiment. It consists of a single CUORE tower (52 TeO2 bolometers of 750 g each, arranged in a 13 floor structure) constructed strictly following CUORE recipes both for materials and assembly procedures. An experiment its own, CUORE-0 is expected to reach a sensitivity to the neutrinoless double beta decay half-life of 130Te around 3E24 y in one year of live time. We present an update of the data, corresponding to an exposure of 18.1 kg y. An analysis of the background indicates that the CUORE performance goal is satisfied while the sensitivity goal is within reach.Comment: 10 pages, 3 figures, to appear in the proceedings of NEUTRINO 2014, 26th International Conference on Neutrino Physics and Astrophysics, 2-7 June 2014, held at Boston, Massachusetts, US