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This article describes the setup and performance of the near and far detectors in the Double Chooz experiment. The electron antineutrinos of the Chooz nuclear power plant were measured in two identically designed detectors with different average baselines of about 400 m and 1050 m from the two reactor cores. Over many years of data taking the neutrino signals were extracted from interactions in the detectors with the goal of measuring a fundamental parameter in the context of neutrino oscillation, the mixing angle θ 13 . The central part of the Double Chooz detectors was a main detector comprising four cylindrical volumes filled with organic liquids. From the inside towards the outside there were volumes containing gadolinium-loaded scintillator, gadolinium-free scintillator, a buffer oil and, optically separated, another liquid scintillator acting as veto system. Above this main detector an additional outer veto system using plastic scintillator strips was installed. The technologies developed in Double Chooz were inspiration for several other antineutrino detectors in the field. The detector design allowed implementation of efficient background rejection techniques including use of pulse shape information provided by the data acquisition system. The Double Chooz detectors featured remarkable stability, in particular for the detected photons, as well as high radiopurity of the detector components. [ABSTRACT FROM AUTHOR]

A θ13 oscillation analysis based on the observed antineutrino rates at the Double Chooz far and near detectors for different reactor power conditions is presented. This approach provides a so far unique simultaneous determination of θ13 and the total background rates without relying on any assumptions on the specific background contributions. The analysis comprises 865 days of data collected in both detectors with at least one reactor in operation. The oscillation results are enhanced by the use of 24.06 days (12.74 days) of reactor-off data in the far (near) detector. The analysis considers the ν ¯ e interactions up to a visible energy of 8.5 MeV, using the events at higher energies to build a cosmogenic background model considering fast-neutrons interactions and 9Li decays. The background-model-independent determination of the mixing angle yields sin2(2θ13) = 0.094 ± 0.017, being the best-fit total background rates fully consistent with the cosmogenic background model. A second oscillation analysis is also performed constraining the total background rates to the cosmogenic background estimates. While the central value is not significantly modified due to the consistency between the reactor-off data and the background estimates, the addition of the background model reduces the uncertainty on θ13 to 0.015. Along with the oscillation results, the normalization of the anti-neutrino rate is measured with a precision of 0.86%, reducing the 1.43% uncertainty associated to the expectation. [ABSTRACT FROM AUTHOR]

numerical method is proposed for determining the diffusion coefficient of a gas in a solid upon its isothermal penetration through a plane-parallel plate and accumulation in a closed receiving volume. The method is tested with the use of mathematical modeling as well as on a specific experimental material. [ABSTRACT FROM AUTHOR]

Structural changes in perovskite and perovskite-like ceramics in the course of thermal treatment were studied by emanation-thermal analysis (ETA) using synthetic calcium metatitanate and aluminotitanate with addition of neodymium and cerium simulating solidified radioactive wastes. The emanation was analyzed as influenced by mechanical (polishing of the surface with diamond paste), radiation (bombardment with helium and krypton ions to certain dozes), and chemical (leaching in aggressive solvents) treatments and by the atmosphere (air, argon, hydrogen) in which the thermal treatment was performed. The ETA curves exhibit characteristic peaks corresponding to regeneration and annealing of both natural structural defects and those appearing after the external treatment of the sample. The model of emanation from material involving structural transformations, which well agrees with experimental data, was proposed. The emanation-thermal analysis under the dynamic conditions allows study of the evolution in the development of the surface relief and solid-state processes proceeding in the fine near-surface layer of material in the course of thermal treatment. It was found that the perovskite-like ceramics, thanks to its high thermal, radiation, mechanical, and chemical stability, can be recommended for solidification and disposal of high-level radioactive wastes. [ABSTRACT FROM AUTHOR]

Emanation thermal analysis (ETA) was used for characterization of the thermal behaviour of a borosilicate glass, designed for the vitrification of hazardous waste. Changes of release rate of radon atoms from the glass sample were measured continuously during heating in an air flow from 20 to 1000°C. Annealing of surface roughness, cracks and technological defects was indicated in the temperature range of 275–400°C by a decrease of radon release rate. A decrease of viscosity of the glass sample (in the proximity of the glass transition temperature, T g) was indicated by the increase of the radon release rate starting at 430°C, whereas the decrease in the radon release rate starting, at 600°C, corresponded to the glass softening. Mathematical modelling was used for the description of the kinetics of radon release from the labelled glass sample and for the simulation of the ETA curve. Good agreement between the experimental data and the results of mathematical modelling of the ETA curve was found. [ABSTRACT FROM AUTHOR]