2,517 research outputs found

    Probing the Temperature Profile of Energy Production in the Sun

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    The particle kinetic energies of pp fusion in the sun (Gamow Energy) produce small changes in the energies of pp solar neutrinos relative to those due only to exothermal energetics. Observation of this effect may be possible via the unique tools of the upcoming LENS solar neutrino detector. The temperature profile of energy production in the sun may thus be directly probed for the first time

    A New Model of Solar Neutrinos in Manifest Violation of CPT Invariance

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    The large mixing (mass)(LMA)-MSW model of solar neutrinos (nue) is now widely held to be near definitive, based on global consistency with data. No physical effect, however, compels its uniqueness. The present search for an explicitly testable competitive model was stimulated by a surprising finding--the high energy part of the standard solar model (SSM) 8B nue spectrum can be scaled very precisely to observed flux levels without measurable shape distortion via sensitive combinations of long wavelength flavor conversion in vacuum and a 8B flux f(B)<f(B:SSM).Pursuantly, a new "astroparticle" model with the relatively specific parameters deltam2 = 76-78 mueV2 (10-12 eV2); sin2 2theta = 0.59-0.55; f(B) =0.8f(B:SSM) coupled with modest changes in the SSM, offers a viable solution consistent with data. Because KamLAND has set deltam2~50x106 mueV2, sin2 2theta~1 for antineutrinos, our model manifestly violates CPT invariance. The model predicts new distortional effects in solar neutrino spectra via nu-e scattering signals in the window 3-5MeV, even though the spectrum is flat above 5 MeV. in This window that is accessible to experiment for the first time in KamLAND. New experiments are proposed to observe the more dramatic charged-current spectral effects.Comment: 25pages, 7 Fig and 4 Tables; Final JCAP Published version (text improved, reference, footnotes added

    Phenomenology of Neutrino Oscillations

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    The phenomenology of solar, atmospheric, supernova and laboratory neutrino oscillations is described. Analytical formulae for matter effects are reviewed. The results from oscillations are confronted with neutrinoless double beta decay.Comment: 11 pages, 2 figures, latex, Plenary talk given at Workshop in High Energy Particle Physics-6, Chennai, Indi

    Neutrino oscillations and uncertainty relations

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    We show that coherent flavor neutrino states are produced (and detected) due to the momentum-coordinate Heisenberg uncertainty relation. The Mandelstam-Tamm time-energy uncertainty relation requires non-stationary neutrino states for oscillations to happen and determines the time interval (propagation length) which is necessary for that. We compare different approaches to neutrino oscillations which are based on different physical assumptions but lead to the same expression for the neutrino transition probability in standard neutrino oscillation experiments. We show that a Moessbauer neutrino experiment could allow to distinguish different approaches and we present arguments in favor of the 163Ho-163Dy system for such an experiment.Comment: Some small changes in section 2, results unchanged. Added referenc

    Economic efficiency of mechanised fishing in Tamil Nadu – a case study in Chennai

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    A study was conducted to analyse the economic efficiency of mechanised fishing in Chennai in Tamil Nadu along the east coast of India. The craft and gear combinations over the years witnessed dramatic changes on account of the huge cost of fishing, duration and depth of operations and maintenance. The mechanised gillnetters showed tremendous increase among the fishing fleet in Chennai mainly due to their assured returns and consistent marketing margin. The present study specifically compares the economic efficiency of mechanised gillnet units and trawlers operating from Chennai. Average operating cost and net income per day for the multiday (MD) gillnetters were `17,757 and 6,613 whereas in the case of multiday trawlers, the operating cost and net income per day were `18,095 and `3,219, respectively. Targeted tuna fishing and better price realisation in the value chain have contributed to better performance of gillnet units. The higher fuel requirement observed for MD trawlers as compared to MD gillnetters is attributed to long distance travelling and the use of mechanical power for propulsion as well as for fishing. The study found that efficiency measures in terms of labour, capital and fuel have established the supremacy of mechanised gillnetters

    Relations between the SNO and the Super Kamiokande solar neutrino rates

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    By comparing the neutrino spectra measured by SNO and Super Kamiokande, we obtain inequalities between the ratios of observed rate to SSM rate for the two experiments. These inequalities apply to a possibly energy-dependent reduction of the SSM flux and to the case of neutrino oscillations. We use them to examine the relationship between the two experiments expected for the MSW and ``Just-So" oscillation scenarios.Comment: 8 pages + 3 figures, REVTeX, uuencoded file created on a VMS syste

    Do Solar Neutrino Experiments Imply New Physics?

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    None of the 1000 solar models in a full Monte Carlo simulation is consistent with the results of the chlorine or the Kamiokande experiments. Even if the solar models are forced artifically to have a \b8 neutrino flux in agreeement with the Kamiokande experiment, none of the fudged models agrees with the chlorine observations. The GALLEX and SAGE experiments, which currently have large statistical uncertainties, differ from the predictions of the standard solar model by 2σ2 \sigma and 3σ3 \sigma, respectively.Comment: 7 pages (figures not included), Institute for Advanced Study number AST 92/51. For a hard copy with the figures, write: [email protected]

    Gamow-Teller Strengths of the Inverse-Beta Transition 176Yb --> 176Lu for Spectroscopy of Proton-Proton and other sub-MeV Solar Neutrinos

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    Discrete Gamow-Teller (GT) transitions, 176Yb-->176Lu at low excitation energies have been measured via the (3He,t) reaction at 450 MeV and at 0 degrees. For 176Yb, two low-lying states are observed, setting low thresholds Q(neutrino)=301 and 445 keV for neutrino capture. Capture rates estimated from the measured GT strengths, the simple two-state excitation structure, and the low Q(neutrino) in Yb--Lu indicate that Yb-based neutrino-detectors are well suited for a direct measurement of the complete sub-MeV solar electron-neutrino spectrum (including pp neutrinos) where definitive effects of flavor conversion are expected

    The Central Temperature of the Sun can be Measured via the 7^7Be Solar Neutrino Line

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    A precise test of the theory of stellar evolution can be performed by measuring the difference in average energy between the neutrino line produced by 7Be{\rm ^7Be} electron capture in the solar interior and the corresponding neutrino line produced in a terrestrial laboratory. The high temperatures in the center of the sun broaden the line asymmetrically, FWHM = 1.6~keV, and cause an average energy shift of 1.3~keV. The width of the 7^7Be neutrino line should be taken into account in calculations of vacuum neutrino oscillations.Comment: RevTeX file, 9 pages. For hardcopy with figure, send to [email protected]. Institute for Advanced Study number AST 93/4

    Developing resources to facilitate culturally-sensitive service planning and delivery – doing research inclusively with people with learning disabilities

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    Background Black, Asian and minority ethnic people with learning disabilities face inequities in health and social care provision. Lower levels of service uptake and satisfaction with services have been reported, however, this is largely based on the views of carers. The ‘Access to Social Care: Learning Disabilities (ASC-LD)’ study sought to explore the views and experiences of social support services among adults with learning disabilities from Black, Asian and minority ethnic communities. Interviews with 32 Black, Asian and minority ethnic adults with learning disabilities were conducted to explore participants’ cultural identities, their understanding and experience of ‘support’. The views and experiences expressed in the ASC-LD study were used in the ‘Tools for Talking project’ to develop a suite of resources designed to facilitate culturally-sensitive communication and information-sharing, service planning and delivery through improved mutual understanding between providers and users of services. This paper describes the Tools for Talking project which sought to co-develop the resources through a partnership event. Methods An inclusive approach was adopted to address issues that are important to people with learning disabilities, to represent their views and experiences, and to involve Black, Asian and minority ethnic people with learning disabilities in the research process. Partnerships were developed with provider organisations and service users who were invited to a ‘Partnership Event’. Collaborators at the partnership event were asked to comment on and evaluate draft resources which included a series of videos and activities to explore topics that emerged as important in the ASC-LD study. Their comments were collated and the tools developed as they suggested. Results Using the results from the ASC-LD study helped to ensure that the draft resources were relevant to service users, addressing topics that were important to them. The partnership event was an effective method to collaborate with a relatively large number of stakeholders. However, the event was resource intensive and required substantial planning to ensure active and meaningful participation. Considerations, such as inviting stakeholders, developing the programme and selecting a venue are discussed. Conclusions The partnership approach has led to the development of a set of five illustrative videos and accompanying activities that address issues that emerged from the collaborative process including: culture, activities, support from staff, important people, choices and independence. These resources are freely available at: www.Toolsfortalking.co.uk. They are designed to be used by users and providers of services, but may also be useful in other settings
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