2,015 research outputs found
In medium effects on the meson
The temperature dependence of the meson mass and its decay width
()have been studied from an effective non-linear
chiral Lagrangian in . Effective mass has been obtained from the pole
position of the full propagator. The width has also been calculated. It has
been found that the mass decreases with temperature very slowly whereas the
decay width increases quite sharply. Possible consequence on the QGP signals is
discussed.Comment: 8 pages + 2 figures (Latex file
The Chandrasekhar limit for quark stars
The Chandrasekhar limit for quark stars is evaluated from simple energy balance relations, as proposed by Landau for white dwarfs or neutron stars. It has been found that the limit for quark stars depends on, in addition to the fundamental constants, the Bag constant
Study of uniformity of characteristics over the surface for triple GEM detector
Study of the uniformity of gain, energy resolution and count rate over active
area of a triple GEM detector has been performed using a strong Fe55 X-ray
source with premixed gas of Argon and CO2 in 70/30 ratio and conventional NIM
electronics. The detail method of measurement and experimental results are
presented in this article.Comment: 5 pages, 3 figure
A new type of RPC with very low resistive material
There are several working groups that are currently working on high rate
RPC's using different materials such as Si-based Ceramics, Low-resistive Glass,
low-resistive bakelite etc. A new type of single gap RPC has been fabricated
using very low-resistive carbon-loaded PTFE material to compete with all these
other groups and materials. In terms of bulk resistivity, this material is the
lowest and should in principle be able to work at the highest rates, provided
the material can withstand working bias and radiation. The efficiency and noise
rate of the RPC are measured with cosmic rays. The detail method of fabrication
and first experimental results are presented.Comment: 6 pages, 4 figure
Multifragmentation model for the production of astrophysical strangelets
Determination of baryon number (or mass) distribution of the strangelets,
that may fragment out of the warm and excited strange quark matter ejected in
the merger of strange stars in compact binary stellar systems in the Galaxy, is
attempted here by using a statistical disassembly model. Finite mass of strange
quarks is taken into account in the analysis. Resulting charges of the
strangelets and the corresponding Coulomb corrections are included to get a
plausible size distribution of those strangelets as they are produced in binary
stellar mergers thus getting injected in the Galaxy. From this mass
distribution of strangelets at their source, an approximate order of magnitude
estimate for their possible flux in solar neighborhood is attempted by using a
simple diffusion model for their propagation in the Galaxy. Such theoretical
estimate is important in view of the ongoing efforts to detect galactic
strangelets by recent satellite-borne experiments.Comment: 17 pages, 6 figure
Study of low energy hadronic interaction models based on BESS observed cosmic ray proton and antiproton spectra at medium high altitude
We study low energy hadronic interaction models based on BESS observed cosmic
ray proton and antiproton spectra at medium high altitude. Among the three
popular low energy interaction models, we find that FLUKA reproduces results of
BESS observations on secondary proton spectrum reasonably well over the whole
observed energy range, the model UrQMD works well at relatively higher energies
whereas spectrum obtained with GHEISHA differs significantly from the measured
spectrum. Simulated antiproton spectrum with FLUKA, however, exhibits
significant deviations from the BESS observation wheras UrQMD and GHEISHA
reproduce the BESS observations within the experimental error.Comment: 7 pages, 7 figure
Disassembly model for the production of astrophysical strangelets
Determination of the baryon number (or mass) distribution of the strangelets,
that may fragment out of the warm and excited strange quark matter (SQM)
ejected in the merger of strange stars (SSs) in compact binary stellar systems
of the Galaxy, is attempted by using a statistical disassembly model (SMM).
Finite mass of strange quarks is taken into account in the analysis. Strangelet
charge and the resulting Coulomb correction are included to get a plausible
mass distribution of galactic strangelets at their source.Comment: 10 pages, 2 figure
Studies of the effect of rate on gain for straw tube detector
Basic R & D have been carried out with one small straw tube detector
prototype with premixed gas of Ar+CO2 in 70:30 and 90:10 ratio. The gain and
the energy resolution are measured with Fe55 X-ray source. Effect of
temperature and pressure on these parameters are measured. The variation of
gain and energy resolution with rate per unit length are also measured. The
details of the test set-up, the method of measurement and the test results are
presented in this paper.Comment: 11 pages, 11 figure
Multi-pronged events from Coulomb fission of nuclei at very low energies
Multi-pronged tracks have been recorded in the polyethylene terephthalate
(CHO) solid state nuclear track detector by exposure to a
Cf fission source. After chemical etching, two-prong to six-pronged
tracks along with single tracks have been observed under the optical
microscope. We carried out a systematic study to understand the origin of the
prongs. The track detectors were coated with metals (Cu, Ag and Pb) and were
exposed to Cf source. After chemical etching two-prong to four pronged
tracks were observed in each plate. We believe that at this very low energy of
the order of 1 MeV/A, Coulomb fission is the only plausible explanation for the
origin of such multi-pronged tracks.Comment: 4 pages, 1 figur
Achieving Efficient Realization of Kalman Filter on CGRA through Algorithm-Architecture Co-design
In this paper, we present efficient realization of Kalman Filter (KF) that
can achieve up to 65% of the theoretical peak performance of underlying
architecture platform. KF is realized using Modified Faddeeva Algorithm (MFA)
as a basic building block due to its versatility and REDEFINE Coarse Grained
Reconfigurable Architecture (CGRA) is used as a platform for experiments since
REDEFINE is capable of supporting realization of a set algorithmic compute
structures at run-time on a Reconfigurable Data-path (RDP). We perform several
hardware and software based optimizations in the realization of KF to achieve
116% improvement in terms of Gflops over the first realization of KF. Overall,
with the presented approach for KF, 4-105x performance improvement in terms of
Gflops/watt over several academically and commercially available realizations
of KF is attained. In REDEFINE, we show that our implementation is scalable and
the performance attained is commensurate with the underlying hardware resourcesComment: Accepted in ARC 201
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