Grand solar minima and maxima deduced from 10Be and 14C: magnetic dynamo configuration and polarity reversal

International audienceAims. This study aims to improve our understanding of the occurrence and origin of grand solar maxima and minima.Methods. We first investigate the statistics of peaks and dips simultaneously occurring in the solar modulation potentials reconstructed using the Greenland Ice Core Project (GRIP) 10Be and IntCal13 14C records for the overlapping time period spanning between ~1650 AD to 6600 BC. Based on the distribution of these events, we propose a method to identify grand minima and maxima periods. By using waiting time distribution analysis, we investigate the nature of grand minima and maxima periods identified based on the criteria as well as the variance and significance of the Hale cycle during these kinds of events throughout the Holocene epoch.Results. Analysis of grand minima and maxima events occurring simultaneously in the solar modulation potentials, reconstructed based on the 14C and the 10Be records, shows that the majority of events characterized by periods of moderate activity levels tend to last less than 50 years: grand maxima periods do not last longer than 100 years, while grand minima can persist slightly longer. The power and the variance of the 22-year Hale cycle increases during grand maxima and decreases during grand minima, compared to periods characterized by moderate activity levels.Conclusions. We present the first reconstruction of the occurrence of grand solar maxima and minima during the Holocene based on simultaneous changes in records of past solar variability derived from tree-ring 14C and ice-core 10Be, respectively. This robust determination of the occurrence of grand solar minima and maxima periods will enable systematic investigations of the influence of grand solar minima and maxima episodes on Earth’s climate

Semi-Empirical Bound on the Chlorinr-37 Solar Neutrino Experiment

The Kamiokande measurement of energetic Boron-8 neutrinos from the sun is used to set a lower bound on the contribution of the same neutrinos to the signal in the \Chlorine\ experiment. Implications for Beryllium-7 neutrinos are discussed.Comment: Latex, 6 pages + 1 postscript figure (included). UTAPHY-HEP-

New Results on Standard Solar Models

We describe the current status of solar modelling and focus on the problems originated with the introduction of solar abundance determinations with low CNO abundance values. We use models computed with solar abundance compilations obtained during the last decade, including the newest published abundances by Asplund and collaborators. Results presented here make focus both on helioseismic properties and the models as well as in the neutrino fluxes predictions. We also discuss changes in radiative opacities to restore agreement between helioseismology, solar models, and solar abundances and show the effect of such modifications on solar neutrino fluxes.Comment: 9 pages. Review talk presented at "Synergies between solar and stellar modelling", Rome, June 2009. To be published by Astrophysics and Space Scienc

A study of the solar neutrino survival probability

We present a study of recent solar neutrino data using a Bayesian method. Assuming that only $\nu_e$ are observed in the Super-Kamiokande experiment our results show a marked supression of the survival probability at about 1 MeV, in good agreement with $\chi ^2$-based analyses. When the detection of $\nu_{\mu}$ by Super-Kamiokande is taken into account, assuming $\nu_e$ to $\nu_{\mu}$ oscillations, we find the largest suppression in survival probability at about 8.5 MeV.Comment: 4 pages, 4 figures, To be published in Physical Review Letter

Accelerator, reactor, solar and atmospheric neutrino oscillation: beyond three generations

We perform a phenomenological analysis of neutrino oscillation in a four generation framework introducing an additional sterile neutrino. In such a scenario, more than one pattern is possible that can accommodate three hieararchically different mass squared differences as required by the present experiments. We considered two different spectrums. Choosing the ${\Delta{m}}^2$s in the ranges suitable for the LSND, atmospheric and solar neutrino oscillation, limits on the mixing angles are derived, consistent with the most restrictive accelerator and reactor data as well as the atmospheric and solar neutrino results. The allowed mixing angles are found to be constrained very severely in both cases. For one mass pattern in the combined allowed zone the atmospheric anomaly can be explained by $\nu_e - \nu_{\mu}$ oscillation whereas for the other the $\nu_{\mu} - \nu_{\tau}$ channel is preferred. The accelerator experiments CHORUS and NOMAD have different sensitivities in these regions and they can distinguish between the two choices.Comment: Latex, 26 pages, 6 figures, 1 included in the Latex File, remaining 5 available on reques