E. B. Norman

An active-shield method for the reduction of surface contamination in CUORE

The main goal of the CUORE experiment is to search for the neutrinoless double beta decay of 130Te. As it is a rare nuclear decay, the sensitivity of the experiment strongly depends on the background level in the transition energy region. In this paper we describe the R&D work performed to develop an active method for the reduction of radioactive background in CUORE. The idea is to reject events originated by surface contamination in large mass bolometric detectors by using bolometers sensitive to surface events. Results obtained with the first prototypes and tests made with large mass surface sensitive bolometers will be reported.

New CUORICINO results on the way to CUORE

CUORE is a 0.75 ton experiment to search for neutrinoless double beta decay of Te130 using 988 TeO2 bolometers. It aims at reaching a sensitivity on the effective neutrino mass of the order of few tens of meV. CUORICINO, a single CUORE tower running since 2003, plays an important role as a stand alone experiment and for developing the future CUORE setup. Present results already achieved and studies that are underway are here presented and discussed.

CUORE: An experiment to investigate for neutrinoless double beta decay by cooling 750 kg of TeO2 crystals at 10mK

CUORE (Cryogenic Underground Observatory for Rare Events) is an experiment proposed to infer the effective Majorana mass of the electron neutrino from measurements on neutrinoless double beta decay (0νDBD). The goal of CUORE is to achieve a background rate in the range 0.001 to 0.01 counts/keV/kg/y at the 0νDBD transition energy of 130Te (2528 keV). The proposed experiment, to be mounted in the underground Gran Sasso INFN National Laboratory, Italy, is realized by cooling about 1000 TeO2 bolometers, of 750 g each, at a temperature of 10mK. We will describe the experiment, to be cooled by an extremely powerful dilution refrigerator, operating with no liquid helium, and the main experimental features designed to assure the predicted sensitivity. We present moreover the last results of a small scale (40.7 kg) 0νDBD experiment carried on in the Gran Sasso Laboratory (CUORICINO).

Nuclear car wash status report, August 2005

A large majority of US imports arrive at seaports in maritime cargo containers. The number of containers arriving is nearly 10 million per year, each with a cargo of up to 30 tons of various materials. This provides a vulnerable entry point for the importation of a nuclear weapon or its components by a terrorist group. Passive radiation sensors are being deployed at portals to detect radioactive material and portable instruments are carried by port personnel to augment detection. Those instruments can detect the neutrons and g-rays produced by {sup 240}Pu that is normally present in weapons grade plutonium in cases where cargo overburden is not too great. However, {sup 235}U produces almost no neutron output in its normal radioactive decay and its principal {gamma}-radiation is at 186 keV and is readily attenuated by small amounts of wood or packing materials. Impurities such as {sup 232}U, often present in reactor irradiated material at the 100-200 ppt level, can provide a detectable signal through significant cargo overburden but the wide variations among samples of HEU make this an unreliable means of detecting SNM. High quality radiography may be useful in determining that the majority of containers are clearly free of SNM. However, some containers will lead to ambiguous results from radiography and passive radiation sensing. For these reasons active neutron interrogation is proposed as a means to produce fission and thus greatly amplify the radiation output of fissionable material to facilitate its reliable detection even when well shielded by large cargo overburden. Historically, the fission signature utilized as the unique identifying feature of fissionable materials is the detection of delayed neutrons. However, these neutrons have very low yield {approx} 0.017 per fission in {sup 235}U, and their low energy results in very poor penetration of hydrogenous materials such as fuels, water, wood, or agricultural products. That signature alone does not provide reliable detection in thick cargos. A new signature has been identified and has been developed within the current project for the detection of well shielded SNM. This SNM signature is based on high-energy {beta}-delayed {gamma}-radiation produced by fission products following neutron or photon induced fission. These {gamma}-rays are high enough in energy (E{sub {gamma}} > 3 MeV) to be readily distinguished from any natural background radioactivity since the latter does not extend above 2.6 MeV. Their abundance is nearly a decade greater than delayed neutrons and their short half-lives deliver nearly all of the signature radiation on time scales of one minute or less and thus facilitate rapid scanning. Finally, for this {gamma}-radiation in the 3-6 MeV range attenuation occurs only by Compton scattering and is in the range where minimum attenuation occurs in all materials. Even the thickest cargos of any material attenuate these {gamma}-rays by only a factor of 10-30X so that the signature is readily detected even with the most challenging shield materials. The goals of the current program are to detect significant quantities (much less than IAEA significant amounts) of well-shielded SNM, and to do so with detection probability P{sub d} {ge} 95% and with false alarm rates P{sub fp} {le} 0.001. It is the goal to meet these requirements in a scan that requires less than one minute to complete and does so without damage to the cargo or to people who may be hidden inside. We intend to meet these requirements even when the cargo overburden is up to {rho}L {le} 150 g/cm{sup 2} of any material ranging from fuels and agricultural products to steel and lead.

Results from cuoricino experiment and prospects for cuore

M. Pedretti, R. Ardito, C. Arnaboldi, D. R. Artusa, F. T. Avignone III, M. Balata, I. Bandac, M. Barucci, J.W. Beeman, F. Bellini, C. Brofferio, C. Bucci, S. Capelli, F. Capozzi, L. Carbone, S. Cebrian, M. Clemenza, C. Cosmelli, O. Cremonesi, R. J. Creswick, I. Dafinei, A. de Waard, M. Diemoz, M. Dolinski, H. A. Farach, F. Ferroni, E. Fiorini, C. Gargiulo, E. Guardincerri, A. Giuliani, P. Gorla, T.D. Gutierrez, E. E. Haller, I. G. Irastorza, E. Longo, G. Maier, R. Maruyama, S. Morganti, S. Nisi, C. Nones, E. B. Norman, A. Nucciotti, E. Olivieri, P. Ottonello, M. Pallavicini, V. Palmieri, M. Pavan, G. Pessina, S. Pirro, E. Previtali, B. Quiter, L. Risegari, C. Rosenfeld, S. Sangiorgio, M. Sisti, A. R. Smith, L. Torres, G. Ventura, N. Xu, and L. Zanotti

Search for beta plus/EC double beta decay of 120Te

We present a search for beta plus/EC double beta decay of 120Te performed with the CUORICINO experiment, an array of TeO2 cryogenic bolometers. After collecting 0.0573 kg y of 120Te, we see no evidence of a signal and therefore set the following limits on the half-life: T1/2 (0nu) > 1.9 10^{21} y at 90% C.L. for the 0 neutrino mode and T1/2 (2nu) > 7.6 10^{19} y at 90% C.L. for the two neutrino mode. These results improve the existing limits by almost three orders of magnitude (four in the case of 0 neutrino mode).

Passive shielding in CUORE

The nature of neutrino mass is one of the friontier problems of fundamental physics. Neutrinoless Double Beta Decay (0νDBD) is a powerful tool to investigate the mass hierarchy and possible extensions of the Standard Model. CUORE is a 1‐Ton next generation experiment, made of 1000 Te bolometers, aiming at reaching a background of 0.01 (possibly 0.001) counts keV−1kg−1y−1 and therefore a mass sensitivity of few tens of meV The background contribution due to environmental neutrons, muon‐induced neutrons in the shieldings and external gamma is discussed.

New CUORICINO results and status of CUORE

CUORICINO is an array of 62 TeO2 bolometers with a total mass of 40.7 kg (11.2 kg of 130Te), operated at about 10 mK to search for ββ(0ν) of 130Te. The detectors are organized as a 14-story tower and intended as a slightly modified version of one of the 19 towers of the CUORE project, a proposed tightly packed array of 988 TeO2 bolometers (741 kg of total mass of TeO2) for ultralow-background searches on neutrinoless double-beta decay, cold dark matter, solar axions, and rare nuclear decays. Started in April 2003 at the Laboratori Nazionali del Gran Sasso (LNGS), CUORICINO data taking was stopped in November 2003 to repair the readout wiring system of the 62 bolometers. Restarted in spring 2004, CUORICINO is presently the most sensitive running experiment on neutrinoless double-beta decay. No evidence for ββ(0ν) decay has been found so far and a new lower limit, T12/0ν ≥ 1.8 × 1024 yr (90% C.L.), is set, corresponding to 〈mν〉 ≤ 0.2–1.1 eV, depending on the theoretical nuclear matrix elements used in the analysis. Detector performance, operational procedures, and background analysis results are reviewed. The expected performance and sensitivity of CUORE is also discussed.