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Tapan Mukhopadhyay

Publications and source records attributed to Tapan Mukhopadhyay.

10 recordsLinked to original sources
arXiv2011

Theoretical estimates of cross sections for neutron-nucleus collisions

We construct an analytical model derived from nuclear reaction theory and having a simple functional form to demonstrate the quantitative agreement with the measured cross sections for neutron induced reactions. The neutron-nucleus total, reaction and scattering cross sections, for energies ranging from 5 to 700 MeV and for several nuclei spanning a wide mass range are estimated. Systematics of neutron scattering cross sections on various materials for neutron energies upto several hundred MeV are important for ADSS applications. The reaction cross sections of neutrons are useful for determining the neutron induced fission yields in actinides and pre-actinides. The present model based on nuclear reaction theory provides good estimates of the total cross section for neutron induced reaction.

nucl-th↗
arXiv2010

Photonuclear reactions of actinides in the giant dipole resonance region

Photonuclear reactions at energies covering the giant dipole resonance (GDR) region are analyzed with an approach based on nuclear photoabsorption followed by the process of competition between light particle evaporation and fission for the excited nucleus. The photoabsorption cross section at energies covering the GDR region is contributed by both the Lorentz type GDR cross section and the quasideuteron cross section. The evaporation-fission process of the compound nucleus is simulated in a Monte-Carlo framework. Photofission reaction cross sections are analyzed in a systematic manner in the energy range of $\sim$ 10-20 MeV for the actinides $^{232}$Th, $^{238}$U and $^{237}$Np. Photonuclear cross sections for the medium-mass nuclei $^{63}$Cu and $^{64}$Zn, for which there are no fission events, are also presented. The study reproduces satisfactorily the available experimental data of photofission cross sections at GDR energy region and the increasing trend of nuclear fissility with the fissility parameter $Z^2/A$ for the actinides.

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arXiv2009

{\Large $γ$} induced multiparticle emissions of medium mass nuclei at intermediate energies

A comprehensive analysis of multiparticle emissions following photon induced reactions at intermediate energies is provided. Photon induced reaction is described in the energy range of $\sim 30-140$ MeV with an approach based on the quasideuteron nuclear photoabsorption model followed by the process of competition between light particle evaporation and fission for the excited nucleus. The evaporation-fission process of the compound nucleus is simulated in a Monte-Carlo framework. The study shows almost no fission events for the medium mass nuclei and reproduces satisfactorily well the available experimental data of photonuclear reaction cross sections at energies $\sim 30-140$ MeV.

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arXiv2007

Relativistic kinematics for reactions involving massless particles

Some useful kinematical relations for the absorption of a photon by a nucleus and its recoil are derived for the relativistic incident energies. These expressions provided for the relativistic kinematics of photoabsorption reactions, though simple, will be immensely useful for experimentalists as well as theoreticians.

nucl-th↗
arXiv2007

Photonuclear reactions of actinide and pre-actinide nuclei at intermediate energies

Photonuclear reaction is described with an approach based on the quasideuteron nuclear photoabsorption model followed by the process of competition between light particle evaporation and fission for the excited nucleus. Thus fission process is considered as a decay mode. The evaporation-fission process of the compound nucleus is simulated in a Monte-Carlo framework. Photofission reaction cross sections are analysed in a systematic manner in the energy range $\sim$~50-70 MeV for the actinides $^{232}$Th, $^{233}$U, $^{235}$U, $^{238}$U and $^{237}$Np and the pre-actinide nuclei $^{208}$Pb and $^{209}$Bi. The study reproduces satisfactorily well the available experimental data of photofission cross sections at energies $\sim$~50-70 MeV and the increasing trend of nuclear fissility with the fissility parameter $Z^2/A$ for the actinides and pre-actinides at intermediate energies [$\sim$~20-140 MeV].

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arXiv2007

Isospin asymmetry in nuclei and nuclear symmetry energy

The volume and surface symmetry parts of the nuclear symmetry energy and other coefficients of the liquid droplet model are determined from the measured atomic masses by the maximum likelihood estimator. The volume symmetry energy coefficient extracted from finite nuclei provides a constraint on the nuclear symmetry energy. This approach also yields the neutron skin of a finite nucleus through its relationship with the volume and surface symmetry terms and the Coulomb energy coefficient. The description of nuclear matter from the isoscalar and isovector components of the density dependent M3Y effective interaction provide a value of the symmetry energy that is consistent with the empirical value of the symmetry energy extracted from measured atomic masses and with other modern theoretical descriptions of nuclear matter.

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arXiv2006

High density behaviour of nuclear symmetry energy

Role of the isospin asymmetry in nuclei and neutron stars, with an emphasis on the density dependence of the nuclear symmetry energy, is discussed. The symmetry energy is obtained using the isoscalar as well as isovector components of the density dependent M3Y effective interaction. The constants of density dependence of the effective interaction are obtained by reproducing the saturation energy per nucleon and the saturation density of spin and isospin symmetric cold infinite nuclear matter. Implications for the density dependence of the symmetry energy in case of a neutron star are discussed, and also possible constraints on the density dependence obtained from finite nuclei are compared.

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arXiv1999

Coherent stochastic resonance in the case of two absorbing boundaries

The coherent stochastic resonance is observed and studied with multi-step periodic signal in continuous medium having two absorbing boundaries. The general features of this process are exihibited. The universal features at the resonance point are demonstrated. The kinetic behaviors around the resonance point are also presented.

cond-mat↗
arXiv1997

Chaos modified wall formula damping of the surface motion of a cavity undergoing fissionlike shape evolutions

The chaos weighted wall formula developed earlier for systems with partially chaotic single particle motion is applied to large amplitude collective motions similar to those in nuclear fission. Considering an ideal gas in a cavity undergoing fission-like shape evolutions, the irreversible energy transfer to the gas is dynamically calculated and compared with the prediction of the chaos weighted wall formula. We conclude that the chaos weighted wall formula provides a fairly accurate description of one body dissipation in dynamical systems similar to fissioning nuclei. We also find a qualitative similarity between the phenomenological friction in nuclear fission and the chaos weighted wall formula. This provides further evidence for one body nature of the dissipative force acting in a fissioning nucleus.

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