Measurement of the Solar Neutrino Capture Rate by the Russian-American Gallium Solar Neutrino Experiment During One Half of the 22-Year Cycle of Solar Activity

We present the results of measurements of the solar neutrino capture rate in gallium metal by the Russian-American Gallium Experiment SAGE during slightly more than half of a 22-year cycle of solar activity. Combined analysis of the data of 92 runs during the 12-year period January 1990 through December 2001 gives a capture rate of solar neutrinos with energy more than 233 keV of 70.8 +5.3/-5.2 (stat.) +3.7/-3.2 (syst.) SNU. This represents only slightly more than half of the predicted standard solar model rate of 128 SNU. We give the results of new runs beginning in April 1998 and the results of combined analysis of all runs since 1990 during yearly, monthly, and bimonthly periods. Using a simple analysis of the SAGE results combined with those from all other solar neutrino experiments, we estimate the electron neutrino pp flux that reaches the Earth to be (4.6 +/- 1.1) E10/(cm^2-s). Assuming that neutrinos oscillate to active flavors the pp neutrino flux emitted in the solar fusion reaction is approximately (7.7 +/- 1.8) E10/(cm^2-s), in agreement with the standard solar model calculation of (5.95 +/- 0.06) E10/(cm^2-s).Comment: English translation of article submitted to Russian journal Zh. Eksp. Teor. Fiz. (JETP); 12 pages, 5 figures. V2: Added winter-summer difference and 2 reference

Observables sensitive to absolute neutrino masses: A reappraisal after WMAP-3y and first MINOS results

In the light of recent neutrino oscillation and non-oscillation data, we revisit the phenomenological constraints applicable to three observables sensitive to absolute neutrino masses: The effective neutrino mass in single beta decay (m_beta); the effective Majorana neutrino mass in neutrinoless double beta decay (m_2beta); and the sum of neutrino masses in cosmology (Sigma). In particular, we include the constraints coming from the first Main Injector Neutrino Oscillation Search (MINOS) data and from the Wilkinson Microwave Anisotropy Probe (WMAP) three-year (3y) data, as well as other relevant cosmological data and priors. We find that the largest neutrino squared mass difference is determined with a 15% accuracy (at 2-sigma) after adding MINOS to world data. We also find upper bounds on the sum of neutrino masses Sigma ranging from ~2 eV (WMAP-3y data only) to ~0.2 eV (all cosmological data) at 2-sigma, in agreement with previous studies. In addition, we discuss the connection of such bounds with those placed on the matter power spectrum normalization parameter sigma_8. We show how the partial degeneracy between Sigma and sigma_8 in WMAP-3y data is broken by adding further cosmological data, and how the overall preference of such data for relatively high values of sigma_8 pushes the upper bound of Sigma in the sub-eV range. Finally, for various combination of data sets, we revisit the (in)compatibility between current Sigma and m_2beta constraints (and claims), and derive quantitative predictions for future single and double beta decay experiments.Comment: 18 pages, including 7 figure

Enhancing Collaborative Learning Through Pedagogical Alignment

his paper presents a study conducted on a mathematics’ course unit where the learner-centred approach was implemented. The study follows a quantitative approach based on surveys, complemented by typical actions of qualitative approach. The pedagogical structure developed is based on the constructive alignment between the objectives, the learning activities and the assessment. A pedagogical strategy with emphasis on the application of the collaborative working group and a comparative study of the outcomes achieved over the academic years of 2017–18 and 2018–19, pointing out some relevant aspects experienced by students, are presented.info:eu-repo/semantics/publishedVersio

Do Solar Neutrino Experiments Imply New Physics?

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 $2 \sigma$ and $3 \sigma$, 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]

Neutrino Lasing in the Sun

Applying the phenomenon of neutrino lasing in the solar interior, we show how the rate for the generic neutrino decay process `\nu -> fermion + boson', can in principal be enhanced by many orders of magnitude over its normal decay rate. Such a large enhancement could be of import to neutrino-decay models invoked in response to the apparent deficit of electron neutrinos observed from the sun. The significance of this result to such models depends on the specific form of the neutrino decay, and the particle model within which it is embedded.Comment: 12 pages, using ordinary TeX. No figure

Our Sun. IV. The Standard Model and Helioseismology: Consequences of Uncertainties in Input Physics and in Observed Solar Parameters

Helioseismology provides a powerful tool to explore the deep interior of the Sun: for example, the adiabatic sound speed can be inferred with an accuracy of a few parts in 10,000. This has become a serious challenge to theoretical models of the Sun. Therefore, we have undertaken a self-consistent, systematic study of sources of uncertainties in the standard solar model, which must be understood before the helioseismic observations can be used as constraints on theory. We find that the largest uncertainty in the sound speed in the solar interior, namely, 3 parts in 1000, arises from uncertainties in the observed photospheric abundances of the elements; uncertainties of 1 part in 1000 arise from (1) the 4% uncertainty in the OPAL opacities, (2) the 5% uncertainty in the basic pp nuclear reaction rate, (3) the 15% uncertainty in the diffusion constants for the gravitational settling of helium, and (4) the 50% uncertainties in diffusion constants for the heavier elements. (Other investigators have shown that similar uncertainties arise from uncertainties in the interior equation of state and in rotation-induced turbulent mixing.) The predicted pre-main-sequence solar lithium depletion is a factor of order 20 (an order of magnitude larger than that predicted by earlier models that neglected gravitational settling and used older opacities), and is uncertain by a factor of 2. The predicted neutrino capture rate is uncertain by 30% for the Cl-37 experiment and by 3% for the Ga-71 experiments (not including uncertainties in the capture cross sections), while the B-8 neutrino flux is uncertain by 30%.Comment: LaTeX, 38 pages (including 8 figures); ApJ, in press. Added figures/color figurea available at http://www.cita.utoronto.ca/~boothroy/sun4.htm

A Natural Framework for Solar and 17 keV Neutrinos

Motivated by recent experimental claims for the existence of a 17 keV neutrino and by the solar neutrino problem, we construct a class of models which contain in their low-energy spectrum a single light sterile neutrino and one or more Nambu-Goldstone bosons. In these models the required pattern of breaking of lepton-number symmetry takes place near the electroweak scale and all mass heirarchies are technically natural. The models are compatible with all cosmological and astrophysical constraints, and can solve the solar neutrino problem via either the MSW effect or vacuum oscillations. The deficit in atmospheric muon neutrinos seen in the Kamiokande and IMB detectors can also be explained in these models.Comment: 23 page