4,792 research outputs found
The Neutrino mass matrix after Kamland and SNO salt enhanced results
An updated analysis of all available neutrino oscillation evidence in Solar
experiments including the latest SNO ES,CC and NC data (254d live time, NaCL
enhanced efficiency) is presented. We obtain, for the fraction of active
oscillating neutrinos:
sin^2alpha=(\Phi_{NC}-\Phi_{CC})/(\Phi_{SSM}-\Phi_{CC})=0.94^{+0.0.065}_{-0.060}
nearly 20\sigma from the pure sterile oscillation case. The fraction of
oscillating sterile neutrinos cos^2\alpha \lsim 0.12 (1 sigma CL). At face
value, these results might slightly favour the existence of a small sterile
oscillating sector. In the framework of two active neutrino oscillations we
determine individual neutrino mixing parameters and their errors we obtain
Delta m^2= 7.01\pm 0.08 \times 10^{-5} eV^2, tan^2 theta=0.42^{+0.12}_{-0.07}.
The main difference with previous analysis is a better resolution in parameter
space. In particular the secondary region at larger mass differences (LMAII) is
now excluded at 95% CL. The combined analysis of solar and Kamland data
concludes that maximal mixing is not favoured at 4-5 sigma. This is not
supported by the antineutrino reactor results alone. We estimate the individual
elements of the two neutrino mass matrix, writing M^2=m^2 I+M_0^2, we obtain (1
sigma errors):
M_0^2=10^{-5} eV^2\pmatrix{
2.06^{+0.29}_{-0.31} & 3.15^{+0.29}_{-0.35} \cr
3.15^{+0.29}_{-0.35} & 4.60^{+0.56}_{-0.44} }
Solar neutrino experiments and Borexino perspectives
We present an updated analysis of all the data available about solar
neutrinos, including the charged current SNO results. The best fit of the data
is obtained in the Large Mixing Angle region, but different solutions are still
possible. We also study the perspectives of Borexino and conclude that this
experiment, with a parallel analysis of total rate and day-night asymmmetry,
should be able to discriminate between the different possible solutions.Comment: 3 pages, Latex, talk given by V. Antonelli at TAUP 2001 Conferenc
KamLAND Bounds on Solar Antineutrinos and neutrino transition magnetic moments
We investigate the possibility of detecting solar electron antineutrinos with
the KamLAND experiment. These electron antineutrinos are predicted by
spin-flavor oscillations at a significant rate even if this mechanism is not
the leading solution to the SNP. KamLAND is sensitive to antineutrinos
originated from solar B neutrinos. From KamLAND negative results after
145 days of data taking, we obtain model independent limits on the total flux
of solar electron antineutrinos $\Phi({}^8 B)< 1.1-3.5\times 10^4 cm^{-2}\
s^{-1}P<0.15%\mu B< 2.3\times 10^{-21}(\Delta m^2, \tan^2\theta)\mu\lsim 3.9\times 10^{-12} \mu_BB= 50\mu\lsim 9.0\times 10^{-13} \mu_BB= 200\mu\lsim 2.0\times 10^{-13} \mu_BB= 1000$ kG at the same
statistical significance.Comment: 13 pages, 2 figure
Solving the solar neutrino problem with kamLAND and BOREXINO
We analyze the expected signals of two future neutrino experiments, kamLAND
and BOREXINO. We show that with just these experiments, we will hopefully be
able to determine which of the existing solutions to the solar neutrino problem
is the real solution. We also analyze existing solar neutrino data and
determine the best-fit points in the oscillation-parameter space finding that
with the inclusion of SNO-charged current, the global-rates analysis gives a
favored LMA solution with a goodness of fit (g.o.f) of just 32.63%, whereas the
g.o.f of the SMA solution is 9.83%. Nonetheless, maximal and quasi-maximal
mixing is not favored. If we include the Superkamiokande spectrum in our \chi^2
analysis, we obtain a LMA solution with a g.o.f. of 84.38%.Comment: 4 pages, 5 figures, Talk given at 37th Rencontres de Moriond on
Electroweak Interactions and Unified Theories, Les Arcs, France, 9-16 Mar
200
The solar neutrino puzzle: present situation and future scenarios
We present a short review of the existing evidence in favor of neutrino mass
and neutrino oscillations which come from different kinds of experiments. We
focus our attention in particular on solar neutrinos, presenting a global
updated phenomenological analysis of all the available data and we comment on
different possible future scenarios.Comment: 22 pp. Expanded version of the contribution to appear in the
Proceedings of ``Les Rencontres de Physique de la Vallee d'Aoste'', February
200
After Sno and Before Kamland: Present and Future of Solar and Reactor Neutrino Physics
We present a short review of the existing evidence in favor of neutrino mass
and neutrino oscillations which come from different kinds of experiments. We
focus our attention in particular on solar neutrinos, presenting a review of
some recent analysis of all available neutrino oscillation evidence in Solar
experiments including the recent and data. We present in detail
the power of the reactor experiment KamLAND for discriminating existing
solutions to the SNP and giving accurate information on neutrino masses and
mixing angles.Comment: Expanded version of the contribution to appear in the Proceedings of
''Third Tropical Workshop on Particle Physics and Cosmology: Neutrinos,
Branes and Cosmology (Puerto Rico, August 2002)'
KamLAND, solar antineutrinos and the solar magnetic field
In this work the possibility of detecting solar electron antineutrinos
produced by a solar core magnetic field from the KamLAND recent observations is
investigated. We find a scaling of the antineutrino probability with respect to
the magnetic field profile in the sense that the same probability function can
be reproduced by any profile with a suitable peak field value. In this way the
solar electron antineutrino spectrum can be unambiguosly predicted. We use this
scaling and the negative results indicated by the KamLAND experiment to obtain
upper bounds on the solar electron antineutrino flux. We get
at 95% CL. For 90% CL this becomes
, an improvement by a factor of 3-5
with respect to existing bounds. These limits are independent of the detailed
structure of the magnetic field in the solar interior. We also derive upper
bounds on the peak field value which are uniquely determined for a fixed solar
field profile. In the most efficient antineutrino producing case, we get (95%
CL) an upper limit on the product of the neutrino magnetic moment by the solar
field MeV or for
.Comment: 15 pages. References corrected. Minor changes in the tex
Usos potenciales de la madera de roble europeo y fresno americano cultivados en la provincia de Buenos Aires, Argentina
- Spavento, E. Ing. Forestal, Docente-Investigadora, XilotecnologÃa y Profesional Independiente. Facultad de Ciencias Agrarias y Forestales, UNLP. [email protected]
- Keil, G. Ing. Forestal M. Sc., Docente-Investigador, XilotecnologÃa e Industrias de Transformación Mecánica. Facultad de Ciencias Agrarias y Forestales, UNLP. [email protected]
- Murace, M. Licenciada en BiologÃa, Docente-Investigadora, Protección Forestal. Facultad de Ciencias Agrarias y Forestales, UNLP. [email protected]
- Luján M . Doctora en Ciencias Naturales, Docente-Investigadora, Facultad de Ciencias Naturales y Museo, UNLP. CIC, PBA.
- Bertoli, B Ingeniero Forestal, Profesional Independiente.Los usos de una madera están estrechamente relacionados a sus caracterÃsticas tecnológicas. Para utilizar con fiabilidad la madera de roble europeo (Quercus robur L.) y fresno americano (Fraxinus pennsylvanica Marsh.) cultivada en la provincia de Buenos Aires (Argentina) es necesario conocer sus propiedades fÃsicomecánicas y su durabilidad. El objetivo de este trabajo fue determinar, mediante ensayos estandarizados, las caracterÃsticas tecnológicas de la madera de roble y fresno, implantados en la provincia de Buenos Aires, con el propósito de definir sus usos. Las propiedades fÃsicas determinadas fueron: contenido de humedad (IRAM 9532), densidades aparentes (IRAM 9544), cambios dimensionales (IRAM 9543). Las propiedades mecánicas determinadas fueron: dureza Janka (IRAM 9570), flexión estática (IRAM 9542), corte paralelo a las fibras (IRAM 9596), compresión perpendicular y paralela a las fibras (IRAM 9547 y 9541 respectivamente). La durabilidad natural se estimó aplicando la norma IRAM 9518. Se estudió además la estructura del leño de ambas especies, a nivel macro y microscópico, con el fin de relacionar estas caracterÃsticas con las propiedades tecnológicas. Para ello se cuantificaron los siguientes caracteres: longitud, espesor de pared y diámetro del lumen de fibras y diámetro de vasos mayores. Ambas maderas resultaron medianamente estables, de densidad media alta y durables. De acuerdo con esto las maderas de roble europeo y fresno americano cultivadas en Argentina son aptas para una amplia gama de usos: elementos deportivos, mangos de herramientas, muebles, escaleras, molduras, puertas, solados interiores y exteriores y elementos estructurales como vigas y columnas, entre otros
- …