120155820
HIGHER DIMENSIONAL COSMOLOGICAL MODEL IN LYRA GEOMETRY: REVISITED
In this paper we have revisited the research work of Rahman and Bera22 on Kaluza–Klein cosmological model within the framework of Lyra Geometry. It has been shown that the empty universe model yields a power law relation without any assumption. The role of bulk viscosity on five-dimensional cosmological model is discussed. The physical behaviour of the models is examined in all cases.
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.
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.
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.
119805930
String cosmology with electromagnetic fields in Bianchi-type-II, -VIII and -IX space-time
SummaryA new class of physically relevant exact cosmological solutions for massive strings in the presence of electromagnetic fields has been obtained in Bianchi-type-II, -VIII and -IX space-time. The physical and the kinematical behaviour of these models have 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.
123842721
Multifractal study of singly charged particles produced in S-32 induced Ag/Br interactions at CERN
In this contribution, we describe an investigation of the fractal nature of non-statistical fluctuations in the density distribution of singly charged secondary particles produced in 32S-Ag/Br interactions in emulsion target at incident energy of 200A GeV. The experimental results have been compared with those obtained from an event sample simulated by the Lund Monte Carlo code FRITIOF. Besides obtaining the fractal dimensions and a smooth multifractal spectrum, show that the results can be used to determine universal parameters such as the Levy index, and the multifractal specific heat.
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.
120167461
Anomalous behavior of the level density parameter in neutron and charged particle evaporation
The compound nucleus $^{76}\mathrm{Kr}*$ was populated at the excitation energy of $75\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ and angular momentum of $39\ensuremath{\hbar}$ in fusion reactions with two complementary, mass-symmetric $(^{31}\mathrm{P}+^{45}\mathrm{Sc})$ and mass-asymmetric $(^{12}\mathrm{C}+^{64}\mathrm{Zn})$ entrance channels. The neutron evaporation spectra were measured and compared with the predictions of statistical model calculations using the transmission coefficients for the spherical nuclei in the inverse absorption channel, the rotating liquid drop model moment of inertia, and the normal systematic value of $A∕8$ for the level density parameter $a$. The results for the mass-asymmetric reaction are found to be consistent with the predictions of the statistical model calculations. However, for the mass-symmetric reaction $(^{31}\mathrm{P}+^{45}\mathrm{Sc})$, the experimental spectra are found to be harder than the theoretical neutron spectra and the statistical model calculations require a lower value of $A∕10$ for the parameter $a$ to reproduce the shape of the experimental spectra, indicating the neutron to be evaporated at higher temperature for the same excitation energy and angular momentum in symmetric system. According to the dynamical model, the formation time $(37\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}22}\phantom{\rule{0.3em}{0ex}}\mathrm{sec})$ of the compound nucleus for the symmetric $^{31}\mathrm{P}+^{45}\mathrm{Sc}$ system is significantly higher than that $(29\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}22}\phantom{\rule{0.3em}{0ex}}\mathrm{sec})$ for the asymmetric $^{12}\mathrm{C}+^{64}\mathrm{Zn}$ system. This may probably lead to the formation of a temperature-equilibrated dinuclear complex that may be responsible for neutron emission at higher temperature in the case of the symmetric system.
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.