1,568 research outputs found

    Lithium Experiment on Solar Neutrinos to Weight the CNO Cycle

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    The measurement of the flux of beryllium neutrinos with the accuracy of about 10% and CNO neutrinos with the accuracy 30% will enable to find the flux of pp-neutrinos in the source with the accuracy better than 1% using the luminosity constraint. The future experiments on \nu e- scattering will enable to measure with very good accuracy the flux of beryllium and pp-neutrinos on the Earth. The ratio of the flux of pp-neutrinos on the Earth and in the source will enable to find with very good accuracy a mixing angle theta solar. Lithium detector has high sensitivity to CNO neutrinos and can find the contribution of CNO cycle to the energy generated in the Sun. This will be a stringent test of the theory of stellar evolution and combined with other experiments will provide a precise determination of the flux of pp-neutrinos in the source and a mixing angle theta solar. The work on the development of the technology of lithium experiment is now in progress.Comment: Minor corrections, one reference added, 11 pages, 2 figures, talk given at NANP 2003, Dubna, Russia, June 200

    Super-Poincare' algebras, space-times and supergravities (I)

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    A new formulation of theories of supergravity as theories satisfying a generalized Principle of General Covariance is given. It is a generalization of the superspace formulation of simple 4D-supergravity of Wess and Zumino and it is designed to obtain geometric descriptions for the supergravities that correspond to the super Poincare' algebras of Alekseevsky and Cortes' classification.Comment: 29 pages, v2: minor improvements at the end of Section 5.

    On Spacetimes with Constant Scalar Invariants

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    We study Lorentzian spacetimes for which all scalar invariants constructed from the Riemann tensor and its covariant derivatives are constant (CSICSI spacetimes). We obtain a number of general results in arbitrary dimensions. We study and construct warped product CSICSI spacetimes and higher-dimensional Kundt CSICSI spacetimes. We show how these spacetimes can be constructed from locally homogeneous spaces and VSIVSI spacetimes. The results suggest a number of conjectures. In particular, it is plausible that for CSICSI spacetimes that are not locally homogeneous the Weyl type is IIII, IIIIII, NN or OO, with any boost weight zero components being constant. We then consider the four-dimensional CSICSI spacetimes in more detail. We show that there are severe constraints on these spacetimes, and we argue that it is plausible that they are either locally homogeneous or that the spacetime necessarily belongs to the Kundt class of CSICSI spacetimes, all of which are constructed. The four-dimensional results lend support to the conjectures in higher dimensions.Comment: 25 pages, 1 figure, v2: minor changes throughou

    The Mersey Estuary : sediment geochemistry

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    This report describes a study of the geochemistry of the Mersey estuary carried out between April 2000 and December 2002. The study was the first in a new programme of surveys of the geochemistry of major British estuaries aimed at enhancing our knowledge and understanding of the distribution of contaminants in estuarine sediments. The report first summarises the physical setting, historical development, geology, hydrography and bathymetry of the Mersey estuary and its catchment. Details of the sampling and analytical programmes are then given followed by a discussion of the sedimentology and geochemistry. The chemistry of the water column and suspended particulate matter have not been studied, the chief concern being with the geochemistry of the surface and near-surface sediments of the Mersey estuary and an examination of their likely sources and present state of contamination

    Coordinated analysis of age, sex, and education effects on change in MMSE scores

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    Objectives. We describe and compare the expected performance trajectories of older adults on the Mini-Mental Status Examination (MMSE) across six independent studies from four countries in the context of a collaborative network of longitudinal studies of aging. A coordinated analysis approach is used to compare patterns of change conditional on sample composition differences related to age, sex, and education. Such coordination accelerates evaluation of particular hypotheses. In particular, we focus on the effect of educational attainment on cognitive decline.Method. Regular and Tobit mixed models were fit to MMSE scores from each study separately. The effects of age, sex, and education were examined based on more than one centering point.Results. Findings were relatively consistent across studies. On average, MMSE scores were lower for older individuals and declined over time. Education predicted MMSE score, but, with two exceptions, was not associated with decline in MMSE over time.Conclusion. A straightforward association between educational attainment and rate of cognitive decline was not supported. Thoughtful consideration is needed when synthesizing evidence across studies, as methodologies adopted and sample characteristics, such as educational attainment, invariably differ. © 2012 The Author

    Current Status of the Solar Neutrino Problem with Super-Kamiokande

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    We perform an updated model-independent analysis using the latest solar neutrino data obtained by 37^{37}Cl and 71^{71}Ga radiochemical experiments, and most notably by a large water-Cherenkov detector SuperKamiokande with their 504 days of data taking. We confirm that the astrophysical solutions to the solar neutrino problem are extremely disfavored by the data and a low-temperature modification of the standard solar model is excluded by more than 5 σ\sigma. We also propose a new way of illuminating the suppression pattern of various solar neutrino flux without invoking detailed flavor conversion mechanisms. It indicates that the strong suppression of 7^7Be neutrinos is no more true when the neutrino flavor conversion is taken into account.Comment: RevTex file, 10 pages, 7 postscript figure

    Correlations of Solar Neutrino Observables for SNO

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    Neutrino oscillation scenarios predict correlations, and zones of avoidance, among measurable quantities such as spectral energy distortions, total fluxes, time dependences, and flavor content. The comparison of observed and predicted correlations will enhance the diagnostic power of solar neutrino experiments. A general test of all presently-allowed (two neutrino) oscillation solutions is that future measurements must yield values outside the predicted zones of avoidance. To illustrate the discriminatory power of the simultaneous analysis of multiple observables, we map currently allowed regions of neutrino masses and mixing angles onto planes of quantities measurable with the Sudbury Neutrino Observatory (SNO). We calculate the correlations that are predicted by vacuum and MSW (active and sterile) neutrino oscillation solutions that are globally consistent with all available neutrino data. We derive approximate analytic expressions for the dependence of individual observables and specific correlations upon neutrino oscillations parameters. We also discuss the prospects for identifying the correct oscillation solution using multiple SNO observables.Comment: Accepted Phys Rev D. Included new figure. Related material http://www.sns.ias.edu/~jn

    How Well Do We (and Will We) Know Solar Neutrino Fluxes and Oscillation Parameters?

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    Assuming neutrino oscillations occur, the pp electron neutrino flux is uncertain by at least a factor of two, the 8B{\rm ^8B} flux by a factor of five, and the 7Be{\rm ^7Be} flux by a factor of forty-five. Calculations of the expected results of future solar neutrino experiments (SuperKamiokande, SNO, BOREXINO, ICARUS, HELLAZ, and HERON) are used to illustrate the extent to which these experiments will restrict the range of the allowed neutrino mixing parameters. We present an improved formulation of the ``luminosity constraint'' and show that at 95\% confidence limit this constraint establishes the best available limits on the rate of creation of pp neutrinos in the solar interior and provides the best upper limit to the 7Be{\rm ^7Be} neutrino flux.Comment: 37 pages, uuencoded Z-compressed postscript file (with figures); Submitted to Physical Review
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