2,559 research outputs found
Nonlinear dynamics of an optomechanical system with a coherent mechanical pump: second-order sideband generation
Second-order sideband generation in a coherent-mechanical pumped optomechanical system is discussed, and the features of the coherent mechanical pump induced enhancement of second-order sideband generation are identified. We show that the coherent mechanical pump induced enhancement of second-order sideband generation exhibits an essential difference between the case of a weak control field and a strong control field. In the weak control field case, the efficiency of second-order sideband generation increases as the amplitude of the mechanical pump increases. In the strong control field case, the effect of optomechanically induced transparency occurs and increasing the amplitude of the mechanical pump does not always bring an enhancement of second-order sideband generation. The phase-dependent effect of the second-order sideband generation with a coherent mechanical pump is also discussed, and it is shown that the phase difference ϕ plays an important role in the process of second-order sideband generation
Characterizing dynamical transitions in bistable system using non-equilibrium measurement of work
We show how Jarzynski relation can be exploited to analyze the nature of
order-disorder and a bifurcation type dynamical transition in terms of a
response function derived on the basis of work distribution over
non-equilibrium paths between two thermalized states. The validity of the
response function extends over linear as well as nonlinear regime and far from
equilibrium situations
Semi-Empirical Bound on the Chlorinr-37 Solar Neutrino Experiment
The Kamiokande measurement of energetic Boron-8 neutrinos from the sun is
used to set a lower bound on the contribution of the same neutrinos to the
signal in the \Chlorine\ experiment. Implications for Beryllium-7 neutrinos are
discussed.Comment: Latex, 6 pages + 1 postscript figure (included). UTAPHY-HEP-
The relativistic continuum Hartree-Bogoliubov description of charge-changing cross section for C,N,O and F isotopes
The ground state properties including radii, density distribution and one
neutron separation energy for C, N, O and F isotopes up to the neutron drip
line are systematically studied by the fully self-consistent microscopic
Relativistic Continuum Hartree-Bogoliubov (RCHB) theory. With the proton
density distribution thus obtained, the charge-changing cross sections for C,
N, O and F isotopes are calculated using the Glauber model. Good agreement with
the data has been achieved. The charge changing cross sections change only
slightly with the neutron number except for proton-rich nuclei. Similar trends
of variations of proton radii and of charge changing cross sections for each
isotope chain is observed which implies that the proton density plays important
role in determining the charge-changing cross sections.Comment: 10 pages, 4 figure
Neutron/proton ratio of nucleon emissions as a probe of neutron skin
The dependence between neutron-to-proton yield ratio () and neutron
skin thickness () in neutron-rich projectile induced reactions is
investigated within the framework of the Isospin-Dependent Quantum Molecular
Dynamics (IQMD) model. The density distribution of the Droplet model is
embedded in the initialization of the neutron and proton densities in the
present IQMD model. By adjusting the diffuseness parameter of neutron density
in the Droplet model for the projectile, the relationship between the neutron
skin thickness and the corresponding in the collisions is obtained.
The results show strong linear correlation between and
for neutron-rich Ca and Ni isotopes. It is suggested that may be used
as an experimental observable to extract for neutron-rich nuclei,
which is very significant to the study of the nuclear structure of exotic
nuclei and the equation of state (EOS) of asymmetric nuclear matter.Comment: 7 pages, 5 figures; accepted by Phys. Lett.
Formation of Episodic Magnetically Driven Radiatively Cooled Plasma Jets in the Laboratory
We report on experiments in which magnetically driven radiatively cooled
plasma jets were produced by a 1 MA, 250 ns current pulse on the MAGPIE pulsed
power facility. The jets were driven by the pressure of a toroidal magnetic
field in a ''magnetic tower'' jet configuration. This scenario is characterized
by the formation of a magnetically collimated plasma jet on the axis of a
magnetic ''bubble'', confined by the ambient medium. The use of a radial
metallic foil instead of the radial wire arrays employed in our previous work
allows for the generation of episodic magnetic tower outflows which emerge
periodically on timescales of ~30 ns. The subsequent magnetic bubbles propagate
with velocities reaching ~300 km/s and interact with previous eruptions leading
to the formation of shocks.Comment: 6 pages, 5 figures. Accepted for publication in Astrophysics & Space
Scienc
Multi-boson effects in Bose-Einstein interferometry and the multiplicity distribution
Multi-boson symmetrization effects on two-particle Bose-Einstein
interferometry are studied for ensembles with arbitrary multiplicity
distributions. This generalizes the previously studied case of a Poissonian
input multiplicity distribution. In the general case we find interesting
residual correlations which require a modified framework for extracting
information on the source geometry from two-particle correlation measurements.
In sources with high phase-space densities, multi-boson effects modify the
Hanbury Brown-Twiss (HBT) radius parameters and simultaneously generate strong
residual correlations. We clarify their effect on the correlation strength
(intercept parameter) and thus explain a variety of previously reported
puzzling multi-boson symmetrization phenomena. Using a class of analytically
solvable Gaussian source models, with and without space-momentum correlations,
we present a comprehensive overview of multi-boson symmetrization effects on
particle interferometry. For event ensembles of (approximately) fixed
multiplicity, the residual correlations lead to a minimum in the correlation
function at non-zero relative momentum, which can be practically exploited to
search, in a model-independent way, for multi-boson symmetrization effects in
high-energy heavy-ion experiments.Comment: 22 pages ReVTex, including 8 postscript figures. Submitted to Annals
of Physics (N.Y.
Gamow-Teller strength distributions for nuclei in pre-supernova stellar cores
Electron-capture and -decay of nuclei in the core of massive stars
play an important role in the stages leading to a type II supernova explosion.
Nuclei in the f-p shell are particularly important for these reactions in the
post Silicon-burning stage of a presupernova star. In this paper, we
characterise the energy distribution of the Gamow-Teller Giant Resonance (GTGR)
for mid-fp-shell nuclei in terms of a few shape parameters, using data obtained
from high energy, forward scattering (p,n) and (n,p) reactions. The energy of
the GTGR centroid is further generalised as function of nuclear
properties like mass number, isospin and other shell model properties of the
nucleus. Since a large fraction of the GT strength lies in the GTGR region, and
the GTGR is accessible for weak transitions taking place at energies relevant
to the cores of presupernova and collapsing stars, our results are relevant to
the study of important -capture and -decay rates of arbitrary,
neutron-rich, f-p shell nuclei in stellar cores. Using the observed GTGR and
Isobaric Analog States (IAS) energy systematics we compare the coupling
coefficients in the Bohr-Mottelson two particle interaction Hamiltonian for
different regions of the Isotope Table.Comment: Revtex, 28 pages +7 figures (PostScript Figures, uuencoded, filename:
Sutfigs.uu). If you have difficulty printing the figures, please contact
[email protected]. Accepted for publication in Phys. Rev. C, Nov 01,
199
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