618 research outputs found

    Sigma web interface for reactor data applications

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    We present Sigma Web interface which provides user-friendly access for online analysis and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The interface includes advanced browsing and search capabilities, interactive plots of cross sections, angular distributions and spectra, nubars, comparisons between evaluated and experimental data, computations for cross section data sets, pre-calculated integral quantities, neutron cross section uncertainties plots and visualization of covariance matrices. Sigma is publicly available at the National Nuclear Data Center website at http://www.nndc.bnl.gov/sigma

    Nuclear matrix element for two neutrino double beta decay from 136Xe

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    The nuclear matrix element for the two neutrino double beta decay (DBD) of 136Xe was evaluated by FSQP (Fermi Surface Quasi Particle model), where experimental GT strengths measured by the charge exchange reaction and those by the beta decay rates were used. The 2 neutrino DBD matrix element is given by the sum of products of the single beta matrix elements via low-lying (Fermi Surface) quasi-particle states in the intermediate nucleus. 136Xe is the semi-magic nucleus with the closed neutron-shell, and the beta + transitions are almost blocked. Thus the 2 neutrino DBD is much suppressed. The evaluated 2 neutrino DBD matrix element is consistent with the observed value.Comment: 7 pages 6 figure

    Sustainable solutions for the construction sector: integration of secondary raw materials in the production cycle of concrete

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    The construction industry is one of the largest consumers of raw materials and energy and one of the highest contributor to green-houses gases emissions. In order to become more sustainable it needs to reduce the use of both raw materials and energy, thus lim-iting its environmental impact. Developing novel technologies to integrate secondary raw materials (i.e. lightweight recycled aggre-gates and alkali activated “cementless” binders - geopolymers) in the production cycle of concrete is an all-inclusive solution to im-prove both sustainability and cost-efficiency of construction industry. SUS-CON “SUStainable, Innovative and Energy-Efficiency CONcrete, based on the integration of all-waste materials” is an European project (duration 2012-2015), which aim was the inte-gration of secondary raw materials in the production cycle of concrete, thus resulting in innovative, sustainable and cost-effective building solutions. This paper presents the main outcomes related to the successful scaling-up of SUS-CON concrete solutions in traditional production plants. Two European industrial concrete producers have been involved, to design and produce both pre-cast components (blocks and panels) and ready-mixed concrete. Recycled polyurethane foams and mixed plastics were used as aggre-gates, PFA (Pulverized Fuel Ash, a by-product of coal fuelled power plants) and GGBS (Ground Granulated Blast furnace Slag, a by-product of iron and steel industries) as binders. Eventually, the installation of SUS-CON concrete solutions on real buildings has been demonstrated, with the construction of three mock-ups located in Europe (Spain, Turkey and Romania

    The oxygen isotopic composition of phytolith assemblages from tropical rainforest soil tops (Queensland, Australia): validation of a new paleoenvironmental tool

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    Phytoliths are micrometric particles of amorphous silica that form inside or between the cells of higher plant tissues throughout the life of a plant. With plant decay, phytoliths are either incorporated into soils or exported to sediments via regional watersheds. Phytolith morphological assemblages are increasingly used as proxy of grassland diversity and tree cover density in inter-tropical areas. Here, we investigate whether, along altitudinal gradients in northeast Queensland (Australia), changes in the δ<sup>18</sup>O signature of soil top phytolith assemblages reflect changes in mean annual temperature (MAT) and in the oxygen isotopic composition of precipitation (δ<sup>18</sup>O<sub>precipitation</sub>), as predicted by equilibrium temperature coefficients previously published for silica. Oxygen isotopic analyses were performed on 16 phytolith samples, after controlled isotopic exchange (CIE), using the IR Laser-Heating Fluorination Technique. Long-term mean annual precipitation (MAP) and MAT values at the sampled sites were calculated by the ANUCLIM software. δ<sup>18</sup>O<sub>precipitation</sub> estimates were calculated using the Bowen and Wilkinson (2002) model, slightly modified. An empirical temperature-dependant relationship was obtained: δ<sup>18</sup>O<sub>wood phytolith-precipitation</sub> (‰ vs. VSMOW) = −0.4 (±0.2) <i>t</i> (°C) + 46 (±3) (<i>R</i><sup>2</sup> = 0.4, <i>p</i> < 0.05; <i>n</i> = 12). Despite the various unknowns introduced when estimating δ<sup>18</sup>O<sub>precipitation</sub> values and the large uncertainties on δ<sup>18</sup>O<sub>wood phytolith</sub> values, the temperature coefficient (−0.4 ± 0.2‰ °C<sup>−1</sup>) is in the range of values previously obtained for natural quartz, fresh and sedimentary diatoms and harvested grass phytoliths (from −0.2 to −0.5‰ °C<sup>−1</sup>). The consistency supports the reliability of δ<sup>18</sup>O<sub>wood phytolith</sub> signatures for recording relative changes in mean annual δ<sup>18</sup>O<sub>soil water</sub> values (which are assumed to be equivalent to the weighted annual δ<sup>18</sup>O<sub> precipitation</sub> values in rainforests environments) and MAT, provided these changes were several ‰ and/or several °C in magnitude

    NNDC Data Services

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    The National Nuclear Data Center has provided remote access to some of its resources since 1986. The major databases and other resources available currently through NNDC Web site are summarized. The National Nuclear Data Center (NNDC) has provided remote access to the nuclear physics databases it maintains and to other resources since 1986. With considerable innovation access is now mostly through the Web. The NNDC Web pages have been modernized to provide a consistent state-of-the-art style. The improved database services and other resources available from the NNOC site at www.nndc.bnl.govwill be described
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