991 research outputs found
Solar neutrinos: the SNO salt phase results and physics of conversion
We have performed analysis of the solar neutrino data including results from
the SNO salt phase as well as the combined analysis of the solar and the
KamLAND results. The best fit values of neutrino parameters are Delta m^2 =
7.1e-5 eV^2, tan^2\theta = 0.40 with the boron flux f_B = 1.04. New SNO results
strongly disfavor maximal mixing and the h-LMA region (Delta m^2 > 1e-4 eV^2)
which is accepted now at the 3-sigma level. We find the 3-sigma upper bounds:
Delta m^2 < 1.7e-4$ eV^2 and tan^2\theta < 0.64, and the lower bound Delta m^2
> 4.8e-5 eV^2. Non-zero 13-mixing does not change these results significantly.
The present data determine quantitatively the physical picture of the solar
neutrino conversion. At high energies relevant for SNO and Super-Kamiokande the
deviation of the effective survival probability from the non-oscillatory value
is about 10 - 14%. The oscillation effect contribution to this difference about
10% and the Earth regeneration is about 3 - 4%. At low energies (E < 1 MeV) the
matter corrections to vacuum oscillation effect are below 5%. The predictions
for the forthcoming measurements are given which include the spectral
distortion and CC/NC ratio at SNO, the Day-Night asymmetry, the KamLAND
spectrum and rate.Comment: figures and some numbers corrected, discussion of coherence loss
added, number of pages slightly change
Solar neutrino spectrum, sterile neutrinos and additional radiation in the Universe
Recent results from the SNO, Super-Kamiokande and Borexino experiments do not
show the expected upturn of the energy spectrum of events (the ratio ) at low energies. At the same time, cosmological observations
testify for possible existence of additional relativistic degrees of freedom in
the early Universe: . These facts strengthen the case
of very light sterile neutrino, , with eV, which mixes weakly with the active neutrinos. The
mixing in the mass eigenstate characterized by can explain an absence of the upturn. The mixing of in
the eigenstate with leads to production of
via oscillations in the Universe and to additional contribution before the big bang nucleosynthesis and later. Such a
mixing can be tested in forthcoming experiments with the atmospheric neutrinos
as well as in future accelerator long baseline experiments. It has substantial
impact on conversion of the supernova neutrinos.Comment: 27 pages, LaTeX, 14 eps figures, 3 figures and additional
considerations adde
Probing New Limits for the Violation of the Equivalence Principle in the solar-reactor neutrino sector as a next to leading order effect
New limits for the Violation of Equivalence Principle (VEP) are obtained
considering the mass-flavor mixing hypothesis. This analysis includes
observations of solar and reactor neutrinos and has obtained a limit for the
VEP parameter contributing to the and
disappearance channels of the order , when it is
assumed that neutrinos are mainly affected by the gravitational potential
due to the Great Attractor.Comment: 9 pages, 14 figure
Eu2+ spin dynamics in the filled skutterudites EuM4Sb12 (M = Fe, Ru, Os)
We report evidence for a close relation between the thermal activation of the
rattling motion of the filler guest atoms, and inhomogeneous spin dynamics of
the Eu2+ spins. The spin dynamics is probed directly by means of Eu2+ electron
spin resonance (ESR), performed in both X-band (9.4 GHz) and Q-band (34 GHz)
frequencies in the temperature interval 4.2 < T < 300 K. A comparative study
with ESR measurements on the Beta-Eu8Ga16Ge30 clathrate compound is presented.
Our results point to a correlation between the rattling motion and the spin
dynamics which may be relevant for the general understanding of the dynamics of
cage systems.Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev.
Agroecologia e sistemas de produção orgânica para pequenos ruminantes.
Marco referencial em Agroecologia (Embrapa, 2006); Agroecologia para quem?; Como fazer Agroecologia; Pecuária orgânica no Brasil e no mundo; Normas para a produção orgânica; Tabela 1 - Procedimentos técnicos para produção animal em agricultura orgânica; Sistemas silvipastoris para pecuária orgânica; Cuidados sanitários em sistemas orgânicos de produção; Projeto em Rede de produção Orgânica e o Projeto Componente Pecuária; Figura 1. Centros de pesquisa da Embrapa, parceiros no projeto em rede de Agricultura orgânica; Manipulação da caatinga para fins pastoris; Tabela 2 - Efeito da manipulação da caatinga sobre a capacidade de suporte e o desempenho de caprinos e ovinos; Sistemas agrossilvipastoril para a região da caatinga; Figura 4. Fluxo do componente animal no sistema agrossilvipastoril; Tabela 3. Disponibilidade de pasto e composição química do pasto e dos suplementos utilizados; Tabela 4.Consumo de suplemento e desempenho de cordeiros na fase de terminação em sistema orgânico de produção; O Projeto "Cabrito Ecológico da Caatinga";Descrição do modelo experimental; Tabela 5 - Desempenho Zootécnico do Sistema de Produção Orgânica de Caprino de Corte na Estação Experimental da Caatinga, Petrolina, Pernambuco. Em 2003 e 2004; Tabela 6 - Médias do peso vivo aos 103 dias (PV103), 158 dias (PV158) e 249 dias (PV252) para machos e fêmeas nos dois anos de avaliação no Modelo Experimental e do Sistema de Produção de um produtor do sertão de Pernambuco no ano de 2004; De unidades de validação a espaços de desenvolvimento participativo de tecnologias; Inclusão do componente animal em sistemas orgânicos de produção vegetal; Tabela 7. Médias do peso vivo, ganho médio diário (GMD) e produçãoo em kg de cordeiros/ha de ovinos SRD terminados em área de coqueiral, em sistema orgânico de produção; Manejo agroecológico de pastagens cultivadas
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