G. Ventura

CUORE: a cryogenic underground observatory for rare events

CUORE is a proposed tightly packed array of 1000 TeO2 bolometers, each being a cube 5cm on a side with a mass of 760g. The array consists of 25 vertical towers, arranged in a square of 5 towers×5 towers, each containing 10 layers of four crystals. The design of the detector is optimized for ultralow-background searches: for neutrinoless double-beta decay of 130Te (33.8% abundance), cold dark matter, solar axions, and rare nuclear decays. A preliminary experiment involving 20 crystals 3×3×6cm3 of 340g has been completed, and a single CUORE tower is being constructed as a smaller-scale experiment called CUORICINO. The expected performance and sensitivity, based on Monte Carlo simulations and extrapolations of present results, are reported.

Physics potential and prospects for the CUORICINO and CUORE experiments

Abstract The Cryogenic Underground Observatory for Rare Events (CUORE) experiment projects to construct and operate an array of 1000 cryogenic thermal detectors of TeO 2 , of a mass of 760 g each, to investigate rare events physics, in particular, double beta decay and non-baryonic particle dark matter. A first step towards CUORE is CUORICINO, an array of 62 bolometers, currently being installed in the Gran Sasso Laboratory. In this paper we report the physics potential of both stages of the experiment regarding neutrinoless double beta decay of 130 Te, WIMP searches and solar axions.The CUORE experiment projects to construct and operate an array of 1000 cryogenic thermal detectors of TeO2, of a mass of 760 g each, to investigate rare events physics, in particular, double beta decay and non baryonic particle dark matter. A first step towards CUORE is CUORICINO, an array of 62 bolometers, currently being installed in the Gran Sasso Laboratory. In this paper we report the physics potential of both stages of the experiment regarding neutrinoless double beta decay of 130Te, WIMP searches and solar axions.

New limit on the neutrinoless betabeta decay of 130Te.

We report the present results of CUORICINO, a search for neutrinoless double-beta (0nu betabeta) decay of 130Te. The detector is an array of 62 TeO2 bolometers with a total active mass of 40.7 kg. The array is cooled by a dilution refrigerator shielded from environmental radioactivity and energetic neutrons, operated at approximately 8 mK in the Gran Sasso Underground Laboratory. No evidence for (0nu betabeta) decay was found and a new lower limit, T(1/2)(0nu) > or = 1.8 x 10(24) yr (90% C.L.) is set, corresponding to [m(nu)] < or = 0.2 to 1.1 eV, depending on the theoretical nuclear matrix elements used in the analysis.

Thermal expansion and thermal conductivity of Torlon at low temperatures

We measured the expansion coefficient of Torlon 4203 (polyamide-imide) as a function of temperature between 4.2 and 295 K. The thermal expansion is lower than that of most polymers. The thermal conductivity k between 0.1 and 5 K was also measured: below 1 K, a quadratic dependence on temperature of k was found, as predicted by the tunnelling model, while the behaviour shown by our data above 1 K suggests the presence of a plateau.

Results from a search for the 0 ν ββ-decay of 130 Te

A detailed description of the CUORICINO 130 Te neutrinoless double-beta (0 νββ) decay experiment is given and recent results are reported. CUORICINO is an array of 62 tellurium oxide (TeO 2 ) bolometers with an active mass of 40.7 kg. It is cooled to ∼8-10 mK by a dilution refrigerator shielded from environmental radioactivity and energetic neutrons. It is running in the Laboratori Nazionali del Gran Sasso (LNGS) in Assergi, Italy. These data represent an exposure of 11.83 kg yr or 91 mole-years of 130 Te. No evidence for 0 νββ-decay was observed and a limit of T 0ν 1/2 ( 130 Te) ≥ 3.0 x 1024 y (90% CL) is set. This corresponds to an upper limit on the effective mass, , between 0.19 and 0.68 eV when analyzed with the many published nuclear structure calculations. In the context of these nuclear models, the values fall within the range corresponding to the claim of evidence of 0 νββ-decay by H. V. Klapdor-Kleingrothaus et al. The experiment continues to acquire data.

Low temperature thermal conductivity of Kevlar

Abstract We measured the thermal conductivity of a Kevlar cord, 0.8 mm in diameter, in the 0.1–2.5 K temperature range. The data were fitted with a power-law: k=(3.9±0.2)×10 −5 T 1.17±0.04 W/cm K . Our results are in good accordance with the existing data at T>2 K .

Results from a search for the

A detailed description of the CUORICINO 130 Te neutrinoless double-beta (0 νββ) decay experiment is given and recent results are reported. CUORICINO is an array of 62 tellurium oxide (TeO 2 ) bolometers with an active mass of 40.7 kg. It is cooled to ∼8-10 mK by a dilution refrigerator shielded from environmental radioactivity and energetic neutrons. It is running in the Laboratori Nazionali del Gran Sasso (LNGS) in Assergi, Italy. These data represent an exposure of 11.83 kg yr or 91 mole-years of 130 Te. No evidence for 0 νββ-decay was observed and a limit of T 0ν 1/2 ( 130 Te) ≥ 3.0 x 1024 y (90% CL) is set. This corresponds to an upper limit on the effective mass, , between 0.19 and 0.68 eV when analyzed with the many published nuclear structure calculations. In the context of these nuclear models, the values fall within the range corresponding to the claim of evidence of 0 νββ-decay by H. V. Klapdor-Kleingrothaus et al. The experiment continues to acquire data.

0\nu\beta\beta

Abstract We measured the thermal conductivity of Kapton HN and Upilex R in the lengthwise direction of a single layer of material. The temperature range was investigated 0.1–9 K for Upilex and 0.2–5 K for Kapton. For both conductivities, we found a linear dependence on temperature that can be ascribed to the presence of crystalline units inside the solids.

-decay of

The measurement of thermal and mechanical properties of materials at cryogenic temperatures gains more and more importance in the field of the application of novel high-tech materials to aerospace industry and in developing scientific instrumentation. We present a simple and inexpensive interferometric dilatometer for the measurement of the thermal expansion of materials in the 4–300 K range. The dilatometer consists of a Michelson tilt-compensated interferometer in which the path difference is given by the variation in length of a sample enclosed in a 4 K cryostat. The compensation for misalignment permits a fast and simple operation routine that configures the instrument as a valuable tool for materials engineering.

^{130}Te

Abstract We measured the expansion coefficient of glass-fibre reinforced nylon as a function of temperature between 4.2 and 300 K. The linear thermal expansion is about half that of unfilled nylon throughout the temperatures investigated. The thermal conductivity in the 0.2–5 K temperature range is very close to that of unfilled nylon and can be represented by the fit curve k =2.42×10 −5 T 1.77 .