2,879 research outputs found
Bulk Viscosity of Magnetized Neutron Star Matter
We study the effect of magnetic field on the bulk viscosity of nuclear matter
in neutron stars. We employ the framework of relativistic mean field theory to
observe the dense nuclear matter in neutron stars. The effects are first
studied for the case when the magnetic field does not exceed the critical value
to confine the electrons to the lowest Landau levels. We then consider the case
of intense magnetic field to evaluate viscosity for the URCA processes and show
that the inequality is no longer required to
be satisfied for the URCA processes to proceed.Comment: Latex 2e file with four postscripts figure
A stable Algebraic Spin Liquid in a Hubbard model
We show the existence of a stable Algebraic Spin Liquid (ASL) phase in a
Hubbard model defined on a honeycomb lattice with spin-dependent hopping that
breaks time-reversal symmetry. The effective spin model is the Kitaev model for
large on-site repulsion. The gaplessness of the emergent Majorana fermions is
protected by the time reversal (TR) invariance of this model. We prove that the
effective spin model is TR invariant in the entire Mott phase thus ensuring the
stability of the ASL. The model can be physically realized in cold atom systems
and we propose experimental signals of the ASL.Comment: Published in PR
Electrooptical Evaluation Techniques of Image Intensifier 'Ibbes - Part I
Passive night vision devices are used for viewing the military targets at low light levels of illuminations during night. In these passive night vision devices, image intensifier tubes areused to amplify scene imagery. The performance of these tubes depends upon electrooptical parameters. The techniques of evaluating these parameters, eg, luminous gain, automatic rightness control and maximum screen luminance, photocathode sensitivity, radiant gain, equivalent background illumination, magnification and distortion, signal-to-noise ratio, veilingglare, screen brightness variation, etc. have been described
Electrooptical Evaluation Techniques of Image Intensifier Tubes-Part I1
In this paper, electrooptical evaluation techniques of image intensifier tubes for some of the important parameters like resolving power, absolute spectral responses of photocathode, spectral response of phosphor screen, modulation transfer function, recovery time, gas grade, and fixed-pattern noise have been described
Nuclear Matter in Intense Magnetic Field and Weak Processes
We study the effect of magnetic field on the dominant neutrino emission
processes in neutron stars.The processes are first calculated for the case when
the magnetic field does not exceed the critical value to confine electrons to
the lowest Landau state.We then consider the more important case of intense
magnetic field to evaluate the direct URCA and the neutronisation processes. In
order to estimate the effect we derive the composition of cold nuclear matter
at high densities and in beta equilibrium, a situation appropriate for neutron
stars. The hadronic interactions are incorporated through the exchange of
scalar and vector mesons in the frame work of relativistic mean field theory.
In addition the effects of anomalous magnetic moments of nucleons are also
considered.Comment: 29 pages (LaTeX) including 7 figure
Small-angle neutron scattering studies on water soluble complexes of poly(ethylene glycol)-based cationic random copolymer and SDS
The interaction of cationic random copolymers of methoxy poly(ethylene glycol) monomethacrylate and (3-(methacryloylamino)propyl) trimethylammonium chloride with oppositely charged surfactant, sodium dodecyl sulphate, and the influence of surfactant association on the polymer conformation have been investigated by small-angle neutron scattering. SANS data showed a positive indication of the formation of RCPSDS complexes. Even though the complete structure of the polyion complexes could not be ascertained, the results obtained give us the information on the local structure in these polymer-surfactant systems. The data were analysed using the log-normal distribution of the polydispersed spherical aggregate model for the local structure in these complexes. For all the systems the median radius and the polydispersity were found to be in the range of 20 ± 2 Šand 0.6 ± 0.05, respectively
Search for TeV -rays from H1426+428 during 2004-07 with the TACTIC telescope
The BL Lac object H1426+428 () is an established source of TeV
-rays and detections of these photons from this object also have
important implications for estimating the Extragalactic Background Light (EBL)
in addition to the understanding of the particle acceleration and -ray
production mechanisms in the AGN jets. We have observed this source for about
244h in 2004, 2006 and 2007 with the TACTIC -ray telescope located at
Mt. Abu, India. Detailed analysis of these data do not indicate the presence of
any statistically significant TeV -ray signal from the source
direction. Accordingly, we have placed an upper limit of
on the integrated
-ray flux at 3 significance level.Comment: 11 pages, 5 figures accepted for publication in Journal of Physics G:
Nuclear and Particle Physic
Superconductivity at 5.5 K in Nb2PdSe5 compound
We report superconductivity in as synthesized Nb2PdSe5, which is similar to
recently discovered Nb2PdS5 compound having very high upper critical field,
clearly above the Pauli paramagnetic limit [Sci. Rep. 3, 1446 (2013)]. A bulk
polycrystalline Nb2PdSe5 sample is synthesized by solid state reaction route in
phase pure structure. The structural characterization has been done by X ray
diffraction, followed by Rietveld refinements, which revealed that Nb2PdSe5
sample is crystallized in monoclinic structure with in space group C2/m.
Structural analysis revealed the formation of sharing of one dimensional PdSe2
chains. Electrical and magnetic measurements confirmed superconductivity in
Nb2PdSe5 compound at 5.5K. Detailed magneto-resistance results, exhibited the
value of upper critical field to be around 8.2Tesla. The estimated Hc2(0) is
within Pauli Paramagnetic limit, which is unlike the Nb2PdS5.Comment: 13 pages text + Fig
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