434 research outputs found
Thermo-refractive noise in gravitational wave antennae
Thermodynamical fluctuations of temperature in mirrors of gravitational wave
antennae may be transformed into additional noise not only through thermal
expansion coefficient but also through temperature dependence of refraction
index. The intensity of this noise is comparable with other known noises and
must be taken into account in future steps of the antennas.Comment: 11 pages, 1 figure, the paper is revised as compared to one accepted
in Phys.Letts.A (new numerical estimates
Thermodynamical fluctuations and photo-thermal shot noise in gravitational wave antennae
Thermodynamical fluctuations of temperature in mirrors of gravitational wave
antennae are transformed through thermal expansion coefficient into additional
noise. This source of noise, which may also be interpreted as fluctuations due
to thermoelastic damping, may not be neglected and leads to the necessity to
reexamine the choice of materials for the mirrors. Additional source of noise
are fluctuations of the mirrors' surfaces caused by optical power absorbed in
dielectrical reflective layers.Comment: 20 pages, 2 figure
Thermodynamical fluctuations in optical mirror coatings
Thermodynamical fluctuations of temperature in mirrors may produce surface
fluctuations not only through thermal expansion in mirror body but also through
thermal expansion in mirror coating. We analyze the last "surface" effect which
can be larger than the first "volume" one due to larger thermal expansion
coefficient of coating material and smaller effective volume. In particular,
these fluctuations may be important in laser interferometric gravitational
antennae.Comment: 12 pages, LaTex, 3 figure
The Simplest Resonant Spin--Flavour Solution to the Solar Neutrino Problem
We re-analyse the resonant spin-flavour (RSF) solutions to the solar neutrino
problem in the framework of analytic solutions to the solar
magneto-hydrodynamics (MHD) equations. By substantially eliminating the
arbitrariness associated to the magnetic field profile due to both mathematical
consistency and physical requirements we propose the simplest scheme (MHD-RSF,
for short) for solar neutrino conversion using realistic static MHD solutions.
Using such effective two-parameter scheme we perform the first global fit of
the recent solar neutrino data, including event rates as well as zenith angle
distributions and recoil electron spectra induced by solar neutrino
interactions in Superkamiokande. We compare quantitatively our simplest MHD-RSF
fit with vacuum oscillation (VAC) and MSW-type (SMA, LMA and LOW) solutions to
the solar neutrino problem using a common well-calibrated theoretical
calculation and fit procedure. We find our MHD-RSF fit to be somewhat better
than those obtained for the favored neutrino oscillation solutions, though not
in a statistically significant way. We briefly discuss the prospects to
disentangle our MHD-RSF scenario at future solar neutrino experiments, giving
some predictions for the SNO experiment.Comment: 26 pages with 6 postscript figures included. Improved presentation
and misprints corrected. Final version to appear in Nucl. Phys.
Optomechanical characterization of acoustic modes in a mirror
We present an experimental study of the internal mechanical vibration modes
of a mirror. We determine the frequency repartition of acoustic resonances via
a spectral analysis of the Brownian motion of the mirror, and the spatial
profile of the acoustic modes by monitoring their mechanical response to a
resonant radiation pressure force swept across the mirror surface. We have
applied this technique to mirrors with cylindrical and plano-convex geometries,
and compared the experimental results to theoretical predictions. We have in
particular observed the gaussian modes predicted for plano-convex mirrors.Comment: 8 pages, 8 figures, RevTe
Solar neutrino problem accounting for self-consistent magnetohydrodynamics solution for solar magnetic fields
The analysis of the resonant spin-flavour (RSF) solutions to the solar neutrino problem in the framework of simplest analytic solutions to the solar magneto-hydrodynamics (MHD) equations is presented. We performed the global fit of the recent solar neutrino data, including event rates as well as day and night recoil electron spectra induced by solar neutrino interactions in SuperKamiokande. We compare quantitatively our simplest MHD-RSF fit with vacuum oscillation (VAC) and MSW--type (SMA, LMA and LOW) solutions to the solar neutrino problem using a common well-calibrated theoretical calculation and fit procedure and find MHD-RSF fit to be somewhat better than those obtained for the favored neutrino oscillation solutions. We made the predictions for future experiments to disentangle the MHD-RSF scenario from other scenarios
Stability analysis of agegraphic dark energy in Brans-Dicke cosmology
Stability analysis of agegraphic dark energy in Brans-Dicke theory is
presented in this paper. We constrain the model parameters with the
observational data and thus the results become broadly consistent with those
expected from experiment. Stability analysis of the model without best fitting
shows that universe may begin from an unstable state passing a saddle point and
finally become stable in future. However, with the best fitted model, There is
no saddle intermediate state. The agegraphic dark energy in the model by itself
exhibits a phantom behavior. However, contribution of cold dark matter on the
effective energy density modifies the state of teh universe from phantom phase
to quintessence one. The statefinder diagnosis also indicates that the universe
leaves an unstable state in the past, passes the LCDM state and finally
approaches the sable state in future.Comment: 15 pages, 12 figure
Azimuthal anisotropy and correlations in p+p, d+Au and Au+Au collisions at 200 GeV
We present the first measurement of directed flow () at RHIC. is
found to be consistent with zero at pseudorapidities from -1.2 to 1.2,
then rises to the level of a couple of percent over the range . The latter observation is similar to data from NA49 if the SPS rapidities
are shifted by the difference in beam rapidity between RHIC and SPS.
Back-to-back jets emitted out-of-plane are found to be suppressed more if
compared to those emitted in-plane, which is consistent with {\it jet
quenching}. Using the scalar product method, we systematically compared
azimuthal correlations from p+p, d+Au and Au+Au collisions. Flow and non-flow
from these three different collision systems are discussed.Comment: Quark Matter 2004 proceeding, 4 pages, 3 figure
Azimuthal anisotropy: the higher harmonics
We report the first observations of the fourth harmonic (v_4) in the
azimuthal distribution of particles at RHIC. The measurement was done taking
advantage of the large elliptic flow generated at RHIC. The integrated v_4 is
about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8)
harmonics upper limits on the magnitudes are reported.Comment: 4 pages, 6 figures, contribution to the Quark Matter 2004 proceeding
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