1,869 research outputs found

    Components of Antineutrino Emission in Nuclear Reactor

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    New νˉe,e{\bar{\nu}_e},e scattering experiments aimed for sensitive searches of the νe{\nu}_e magnetic moment and projects to explore small mixing angle oscillations at reactors call for a better understanding of the reactor antineutrino spectrum. Here we consider six components, which contribute to the total νˉe{\bar{\nu}_e} spectrum generated in nuclear reactor. They are: beta decay of the fission fragments of 235^{235}U, 239^{239}Pu, 238^{238}U and 241^{241}Pu, decay of beta-emitters produced as a result of neutron capture in 238^{238}U and also due to neutron capture in accumulated fission fragments which perturbs the spectrum. For antineutrino energies less than 3.5 MeV we tabulate evolution of νˉe{\bar{\nu}_e} spectra corresponding to each of the four fissile isotopes vs fuel irradiation time and their decay after the irradiation is stopped and also estimate relevant uncertainties. Small corrections to the ILL spectra are considered.Comment: LaTex 8 pages, 2 ps figure

    Neutrino magnetic moments and low-energy solar neutrino-electron scattering experiments

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    The scattering of solar neutrinos on electrons is sensitive to the neutrino magnetic moments through an interference of electromagnetic and weak amplitudes in the cross section. We show that future low-energy solar neutrino experiments with good angular resolution can be sensitive to the resulting azimuthal asymmetries in event number and should provide useful information on non-standard neutrino properties such as magnetic moments. We compare asymmetries expected at HELLAZ (mainly pp neutrinos) with those at the Kamiokande and Super-Kamiokande experiments (Boron neutrinos), both for the case of Dirac and Majorana neutrinos and discuss the advantages of low energies. Potentially interesting information on the solar magnetic fields may be accessible.Comment: 21 pages, latex, 5 PS figures, uses revtex, text improved, to be published in Phys. Rev.

    Solar neutrinos: global analysis with day and night spectra from SNO

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    We perform global analysis of the solar neutrino data including the day and night spectra of events at SNO. In the context of two active neutrino mixing, the best fit of the data is provided by the LMA MSW solution with Delta m^2 = 6.15 10^{-5} eV^2, tan^2\theta = 0.41, f_B = 1.05, where f_B is the boron neutrino flux in units of the corresponding flux in the Standard Solar Model (SSM). At 3 sigma level we find the following upper bounds: tan^2\theta < 0.84 and Delta m^2 < 3.6 10^{-4} eV^2. From 1 sigma-interval we expect the day-night asymmetries of the charged current and electron scattering events to be: A_{DN}^{CC} = 3.9 +3.6-2.9 and A_{DN}^{ES} = 2.1 +2.1-1.4. The only other solution which appears at 3 sigma-level is the VAC solution with Delta m^2 = 4.5 10^{-10} eV^2, tan^2\theta = 2.1 and f_B=0.75. The best fit point in the LOW region, with Delta m^2 = 0.93 10^{-7} eV^2 and tan^2\theta = 0.64, is accepted at 99.95% (3.5 sigma) C.L. . The least chi^2 point from the SMA solution region, with Delta m^2 = 4.6 10^{-6} eV^2 and tan^2\theta = 5 10^{-4}, could be accepted at 5.5 sigma-level only. In the three neutrino context the influence of theta_{13} is studied. We find that with increase of theta_{13} the LMA best fit point shifts to larger Delta m^2, mixing angle is practically unchanged, and the quality of the fit becomes worse. The fits of LOW and SMA slightly improve. Predictions for KamLAND experiment (total rates, spectrum distortion) have been calculated.Comment: Typos corrected, reference adde

    Neutrino spin-flips in curved space-time

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    The general relativistic effects on spin-flavor oscillations above the core of type II supernovae are investigated. The evolution equation is derived and the relative magnitudes of the terms in the Hamiltonian, which arise from the weak, electromagnetic and gravitational interaction, are compared. The effects on the resonance position and the adiabaticity are studied. Explicit calculations are presented for non-rotating and slowly rotating stars.Comment: 16 pages, 1 figure, accepted by Phys. Rev.

    Spin-Flavour Oscillations and Neutrinos from SN1987A

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    The neutrino signal from SN1987A is analysed with respect to spin-flavour oscillations between electron antineutrinos, νˉe\bar{\nu}_{e}, and muon neutrinos, νμ\nu_{\mu}, by means of a maximum likelihood analysis. Following Jegerlehner et al. best fit values for the total energy released in neutrinos, EtE_t, and the temperature of the electron antineutrino, TνˉeT_{\bar{\nu}_{e}}, for a range of mixing parameters and progenitor models are calculated. In particular the dependence of the inferred quantities on the metallicity of the supernova is investigated and the uncertainties involved in using the neutrino signal to determine the neutrino magnetic moment are pointed out.Comment: 14 pages, RevTeX, 4 figures, to appear in Physical Review

    Do national resources have to be centrally managed? Vested interests and institutional reform in Norwegian fisheries governance

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    Corporatism -with its privileged access, restricted participation and centralized structures - has a long history in Norwegian fisheries governance. Co-management – understood as a decentralized, bottom-up and more inclusive form of fisheries governance - has not been considered a relevant alternative.. Why does corporatism still prevail in a context where stakeholder status in fisheries governance globally – both in principle and practice - has been awarded environmental organizations, municipal authorities and even consumer advocacy groups? Why then have alternatives to the corporatist system of centralized consultation and state governance never been seriously considered in Norway, in spite of the growing emphasis on fish as a public resource and fisheries management as human intervention in geographically confined and complex ecosystems? We suggest that thismay have to do with the fundamental assumptions behind Norwegian fisheries governance that since fish is a national resource, it must be centrally managed. We argue that this is an assumption that may be contested

    Complete chloroplast genome sequence of Holoparasite Cistanche Deserticola (Orobanchaceae) reveals gene loss and horizontal gene transfer from Its host Haloxylon Ammodendron (Chenopodiaceae)

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    The central function of chloroplasts is to carry out photosynthesis, and its gene content and structure are highly conserved across land plants. Parasitic plants, which have reduced photosynthetic ability, suffer gene losses from the chloroplast (cp) genome accompanied by the relaxation of selective constraints. Compared with the rapid rise in the number of cp genome sequences of photosynthetic organisms, there are limited data sets from parasitic plants. The authors report the complete sequence of the cp genome of Cistanche deserticola, a holoparasitic desert species belonging to the family Orobanchaceae

    Investigate a Gas Well Performance Using Nodal Analysis

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    Gas condensate well has unique reservoir characteristics and ups and downs in well behaviour affect the production rate significantly. A proper optimization can reduce the operating cost, maximize the hydrocarbon recovery and increase the net present value. Well level optimization can be achieved through optimizing well parameters, such as wellhead, tubing size, and skin factor. All of these factors have been investigated using a real field of Thrace Basin and PROSPER simulation program. The history matching data are validated to identify the future performance prediction for the same reservoir deliverability following the period changes. Therefore, predicted results are compared and validated with measured field data to provide the best production practices. Moreover, the results show that the skin factor has a large influence on the production rate by 45% reduction. The reduction in the reservoir pressure declines the production rate dramatically resulted in 70% decline. While manipulating the wellhead pressure shows minor decline compare to tubing size that does not show any significant change to production rate

    Supernova prompt neutronization neutrinos and neutrino magnetic moments

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    It is shown that the combined action of spin-flavor conversions of supernova neutrinos due to the interactions of their Majorana-type transition magnetic moments with the supernova magnetic fields and flavor conversions due to the mass mixing can lead to the transformation of \nu_e born in the neutronization process into their antiparticles \bar{\nu}_e. Such an effect would have a clear experimental signature and its observation would be a smoking gun evidence for the neutrino transition magnetic moments. It would also signify the leptonic mixing parameter |U_{e3}| in excess of 10^{-2}.Comment: LaTex, 25 pages, 3 figures. v4: Discussion section expanded, references added. Matches the published versio
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