44 research outputs found
The Friedel-Crafts Reaction with Furans
2-Furoic acid, aluminum chloride and substituted benzenes give 6-substituted-l-naphthoic acids. For example, with chlorobenzene the product is 6-chloro-1-naphthoic acid; with anisole, 6-methoxy-1-naphthoic acid; with toluene, 6-methyl-1-naphthoic acid
Screening of Nuclear Reactions in the Sun and Solar Neutrinos
We quantitatively determine the effect and the uncertainty on solar neutrino
production arising from the screening process. We present predictions for the
solar neutrino fluxes and signals obtained with different screening models
available in the literature and by using our stellar evolution code. We explain
these numerical results in terms of simple laws relating the screening factors
with the neutrino fluxes. Futhermore we explore a wider range of models for
screening, obtained from the Mitler model by introducing and varying two
phenomenological parameters, taking into account effects not included in the
Mitler prescription. Screening implies, with respect to a no-screening case, a
central temperat reduction of 0.5%, a 2% (8%) increase of Beryllium
(Boron)-neutrino flux and a 2% (12%) increase of the Gallium (Chlorine) signal.
We also find that uncertainties due to the screening effect ar at the level of
1% for the predicted Beryllium-neutrino flux and Gallium signal, not exceeding
3% for the Boron-neutrino flux and the Chlorine signal.Comment: postscript file 11 pages + 4 figures compressed and uuencoded we have
replaced the previous paper with a uuencoded file (the text is the same) for
any problem please write to [email protected]
The relativistic impulse approximation for the exclusive electrodisintegration of the deuteron
The electrodisintegration of the deuteron in the frame of the Bethe-Salpeter
approach with a separable kernel of the nucleon-nucleon interaction is
considered. This conception keeps the covariance of a description of the
process. A comparison of relativistic and nonrelativistic calculations is
presented. The factorization of the cross section of the reaction in the
impulse approximation is obtained by analytical calculations. It is shown that
the photon-neutron interaction plays an important role.Comment: 31 pages, 14 figures, 1 tabl
Neutrinos from the Sun: experimental results confronted with solar models
For standard neutrinos, recent solar neutrino results together with the
assumption of a nuclearly powered Sun imply severe constraints on the
individual components of the total neutrino flux: \Phi_{Be}<0.7*10^9cm^-2 s^-1,
\Phi_{CNO}< 0.6*10^9 cm^-2 s^-1, and $64*10^9 cm^-2 s^-1< \Phi_{pp+pep} <
65*10^9 cm^-2 s^-1 (at 1 \sigma level). The bound on \Phi_{Be} is in strong
disagreement with the standard solar model prediction \Phi_{Be}^{SSM}\approx
5*10^9 cm^-2 s^-1. We study a large variety of non-standard solar models with
low inner temperature, finding that the temperature profiles T(m) follow the
homology relationship: T(m)=kT^{SSM}(m), so that they are specified just by the
central temperature T_c. There is no value of T_c which can account for all the
available experimental results. Even if we only consider the Gallium and
Kamiokande results, they remain incompatible. Lowering the cross section p+Be7
\to \gamma+B8 is not a remedy. The shift of the nuclear fusion chain towards
the pp-I termination could be induced by a hypothetical low energy resonance in
the He3+He3 reaction. This mechanism gives a somehow better, but still bad fit
to the combined experimental data. We also discuss what can be learnt from new
generation experiments about the properties of neutrinos and of the Sun.Comment: 20 pages in RevTeX 3.0 plus 14 figures in uuencoded postscript file
Covariant description of inelastic electron--deuteron scattering:predictions of the relativistic impulse approximation
Using the covariant spectator theory and the transversity formalism, the
unpolarized, coincidence cross section for deuteron electrodisintegration,
, is studied. The relativistic kinematics are reviewed, and simple
theoretical formulae for the relativistic impulse approximation (RIA) are
derived and discussed. Numerical predictions for the scattering in the high
region obtained from the RIA and five other approximations are presented
and compared. We conclude that measurements of the unpolarized coincidence
cross section and the asymmetry , to an accuracy that will distinguish
between different theoretical models, is feasible over most of the wide
kinematic range accessible at Jefferson Lab.Comment: 54 pages and 24 figure
The Russian-American gallium experiment (SAGE) Cr neutrino source measurement
No description supplie
The quest for the solar g modes
Solar gravity modes (or g modes) -- oscillations of the solar interior for
which buoyancy acts as the restoring force -- have the potential to provide
unprecedented inference on the structure and dynamics of the solar core,
inference that is not possible with the well observed acoustic modes (or p
modes). The high amplitude of the g-mode eigenfunctions in the core and the
evanesence of the modes in the convection zone make the modes particularly
sensitive to the physical and dynamical conditions in the core. Owing to the
existence of the convection zone, the g modes have very low amplitudes at
photospheric levels, which makes the modes extremely hard to detect. In this
paper, we review the current state of play regarding attempts to detect g
modes. We review the theory of g modes, including theoretical estimation of the
g-mode frequencies, amplitudes and damping rates. Then we go on to discuss the
techniques that have been used to try to detect g modes. We review results in
the literature, and finish by looking to the future, and the potential advances
that can be made -- from both data and data-analysis perspectives -- to give
unambiguous detections of individual g modes. The review ends by concluding
that, at the time of writing, there is indeed a consensus amongst the authors
that there is currently no undisputed detection of solar g modes.Comment: 71 pages, 18 figures, accepted by Astronomy and Astrophysics Revie
Neutrino Masses and Mixing: Evidence and Implications
Measurements of various features of the fluxes of atmospheric and solar
neutrinos have provided evidence for neutrino oscillations and therefore for
neutrino masses and mixing. We review the phenomenology of neutrino
oscillations in vacuum and in matter. We present the existing evidence from
solar and atmospheric neutrinos as well as the results from laboratory
searches, including the final status of the LSND experiment. We describe the
theoretical inputs that are used to interpret the experimental results in terms
of neutrino oscillations. We derive the allowed ranges for the mass and mixing
parameters in three frameworks: First, each set of observations is analyzed
separately in a two-neutrino framework; Second, the data from solar and
atmospheric neutrinos are analyzed in a three active neutrino framework; Third,
the LSND results are added, and the status of accommodating all three signals
in the framework of three active and one sterile light neutrinos is presented.
We review the theoretical implications of these results: the existence of new
physics, the estimate of the scale of this new physics and the lessons for
grand unified theories, for supersymmetric models with R-parity violation, for
models of extra dimensions and singlet fermions in the bulk, and for flavor
models.Comment: Added note on the effects of KamLAND results. Two new figure
Where do we stand with solar neutrino oscillations?
We determine the neutrino parameters for MSW and vacuum oscillations (active
and sterile neutrinos) that are allowed by the separate, and collective,
imposition of the constraints from total event rates in the chlorine, GALLEX,
SAGE, and SuperKamiokande experiments (504 days), the SuperKamiokande electron
energy spectrum, and the SuperKamiokande zenith-angle dependence. The small
mixing angle MSW solution is acceptable at the 7% C.L. (8% for sterile nu's)
and the vacuum solution is acceptable at the 6% C.L. . The best-fit global MSW
solution for active neutrinos is: Delta m^2 = 5 x 10^-6 eV^2, sin^2 (2 theta) =
5.5 x 10^{-3} (and for sterile neutrinos: Delta m^2 = 4 x 10^-6 eV^2, sin^2 (2
theta) = 7 x 10^-3). For vacuum oscillations, the best-fit solution is: Delta
m^2 = 6.5 x 10^-11 eV^2, sin^2 (2 theta) = 0.75 . An arbitrary combination of
undistorted (no oscillations) pp, 7Be, 8B, and CNO neutrino fluxes is
inconsistent with the combined data sets at the 3.5 sigma C.L., independent of
astrophysical considerations. We use improved calculations of solar model
fluxes, neutrino absorption cross sections and energy spectra, and a detailed
evaluation of regeneration effects.Comment: LaTeX file. Added Figure comparing with SuperK spectrum. Predictions
for LENS experiment. Viewgraphs and related information at
http://www.sns.ias.edu/~jn
The deuteron: structure and form factors
A brief review of the history of the discovery of the deuteron in provided.
The current status of both experiment and theory for the elastic electron
scattering is then presented.Comment: 80 pages, 33 figures, submited to Advances in Nuclear Physic