122637587
Bianchi type III and Kantowski-Sachs cosmological models in Lyra geometry
The cosmological models for Bianchi type III and Kantowski-Sachs space-time within the framework of Lyra geometry are obtained. The physical behaviour of the models have also been discussed.
120875055
Charged fluid distribution in higher dimensional spheroidal space-time
A general solution of Einstein field equations corresponding to a charged fluid distribution on the background of higher dimensional spheroidal space-time is obtained. The solution generates several known solutions for superdense star having spheroidal space-time geometry.
116888804
Bianchi type V and VI0 cosmological models in Lyra geometry
The Bianchi type V and VI0 models have been investigated in Lyra geometry in both the cases with the gauge function β is a time dependent and β=constant. The physical behaviour of these models has been discussed.
121973847
Liouville space-time in general projective relativity
Vacuum field equations of general projective relativity have been solved for Liouville space-time. Finally harmonic coordinate condition and singular behaviour of Kretschmann scalar for the solution is discussed.
121611284
Some cosmological models with constant deceleration parameter
SummaryBerman (1983) presented a law of variation of Hubble’s parameter that yields constant deceleration parameter models of the Universe. In this paper, Robertson-Walker models have been studied in Einstein’s theory with cosmological term and in cosmological theory based on Lyra’s geometry. Some simple models have been obtained. The necessary relations in each model have been derived, considering a perfect fluid.
119358995
A unified approach to charged-fluid distributions in general relativity
SummaryThe exact solutions for a charged perfect fluid are derived. The general analytical solution obtained depends on an arbitrary function of one of the space coordinates. As an illustration of the proposed method, the solution for a charged infinite plane has been obtained.
1536642
Montage: a grid portal and software toolkit for science-grade astronomical image mosaicking
Montage is a portable software toolkit to construct custom, science-grade mosaics that preserve the astrometry and photometry of astronomical sources. The user specifies the dataset, wavelength, sky location, mosaic size, coordinate system, projection, and spatial sampling. Montage supports massive astronomical datasets that may be stored in distributed archives. Montage can be run on both single- and multi-processor computers, including clusters and grids. Standard grid tools are used to access remote data or run Montage on remote computers. This paper describes the architecture, algorithms, performance, and usage of Montage as both a software toolkit and a grid portal.
120176685
Intermittency and multiplicity moments of charged particles produced in 32S–Ag/Br interaction at 200 A GeV/c
The nature of nonstatistical fluctuations in the density distribution of singly charged particles produced in 32S–Ag/Br interactions at an incident momentum of 200 A GeV/c has been investigated. With the help of the nuclear photographic emulsion technique, the data were collected, and using different statistical methods of multiplicity moments these data have been analysed in terms of intermittency and fractal properties of one- and two-dimensional phase space distributions. Wherever possible, experimental results have been compared with the results obtained in other similar heavy-ion-induced experiments, as well as with those obtained from simulated events of the Lund Monte Carlo code FRITIOF. In some cases events simulated by generating (pseudo)random numbers have also been used for the purpose of comparison. The investigation shows the presence of weak intermittency in one dimension (1D) that is consistent with self-similarity in the density distribution. In two dimensions (2D), anisotropy in the distributions along longitudinal and transverse phase space variables indicates that self-affinity, rather than self-similarity in the distributions, is responsible for the observed behaviour. From the analysis of factorial correlators and oscillatory multiplicity moments, the presence of a few-particle short-range correlation has also been established. In almost all cases, the simulated interactions fail to replicate the experimental results.
122026076
Role of nuclear dissipation and entrance channel mass asymmetry in pre-scission neutron multiplicity enhancement in fusion-fission reactions
Pre-scission neutron multiplicities are measured for ${}^{12}\mathrm{C} + {}^{204}\mathrm{Pb}$ and ${}^{19}\mathrm{F} + {}^{197}\mathrm{Au}$ reactions at laboratory energies of 75\char21{}95 MeV for the $^{12}\mathrm{C}$ beam and 98\char21{}118 MeV for the $^{19}\mathrm{F}$ beam. The chosen projectile-target combinations in the present study lie on either side of the Businaro-Gallone mass asymmetry (${\ensuremath{\alpha}}_{\mathrm{BG}}$) and populate the $^{216}\mathrm{Ra}$ compound nucleus. The dissipation strength is deduced after comparing the experimentally measured neutron yield with the statistical model predictions which contains the nuclear viscosity as a free parameter. Present results demonstrate the combined effects of entrance channel mass asymmetry and the dissipative property of nuclear matter on the pre-scission neutron multiplicity in fusion-fission reactions.
120377524
Measurement of neutron multiplicity from fission of {sup 228}U and nuclear dissipation
Pre- and post-scission neutron multiplicities are measured at different excitation energies of the compound nucleus {sup 228}U populated using the {sup 19}F+{sup 209}Bi reaction. The measured yield of pre-scission and total neutrons are compared with the statistical model calculation for the decay of a compound nucleus. The statistical model calculations are performed using the Bohr-Wheeler transition state fission width as well as the dissipative dynamical fission width due to Kramers. Comparison between the measured and the calculated values shows that, while the Bohr-Wheeler fission width grossly underestimates the pre-scission neutron yield, a large amount of dissipation is required in the Kramers width to fit the experimental pre-scission multiplicities. Various factors contributing to the large excitation energy dependence of the fitted values of the dissipation coefficient are discussed.
54082430
Ring and jet-like structures and two-dimensional intermittency in nucleus–nucleus collisions at 200AGeV/c
Abstract We have investigated the presence of ring and/or jet-like structures in the angular emission of secondary charged mesons (shower tracks) coming out of 16O–Ag/Br and 32S–Ag/Br interactions, each at an incident momentum of 200 A GeV / c . Nuclear photographic emulsion technique has been used to collect the experimental data. The experimental results have been compared with the results simulated by Monte Carlo method. The analysis indicates presence of ring and jet-like structures in the experimental data beyond statistical noise. This kind of jet structure is expected to give rise to a strong two-dimensional ( 2 d ) intermittency. The self-affine behaviour of 2d scaled factorial moments (SFM) has therefore been investigated and the strength of 2d intermittency has been determined. For each set of data the 2d results have been compared with the respective one-dimensional ( 1 d ) intermittency results.