A5047739319- Nuclear physics research studies
- Nuclear reactor physics and engineering
- Astronomical and nuclear sciences
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Quantum chaos and dynamical systems
- Quantum, superfluid, helium dynamics
- stochastic dynamics and bifurcation
- Neutrino Physics Research
- Advanced Chemical Physics Studies
- Cold Fusion and Nuclear Reactions
- Atomic and Subatomic Physics Research
- Nuclear Materials and Properties
- High-pressure geophysics and materials
- Advanced NMR Techniques and Applications
- Nuclear Issues and Defense
- X-ray Spectroscopy and Fluorescence Analysis
- Diffusion and Search Dynamics
- Spectroscopy and Quantum Chemical Studies
- Optical measurement and interference techniques
- Molecular Spectroscopy and Structure
- Crystallography and Radiation Phenomena
- Isotope Analysis in Ecology
Variable Energy Cyclotron Centre
2015-2024
Homi Bhabha National Institute
2017-2024
Michigan State University
2016-2019
Banaras Hindu University
2019
Panjab University
2013-2015
Oak Ridge National Laboratory
2013-2015
University of Tennessee at Knoxville
2013-2015
Joint Institute for Computational Sciences
2013
Superheavy atoms and their nuclei are at the forefront of experimental theoretical nuclear atomic physics, chemistry. Because large numbers, traditional concepts have to be revised in superheavy systems. In this Colloquium latest developments field described route for future scientific explorations area research is indicated.
There has been much recent interest in nuclear fission, due part to a new appreciation of its relevance astrophysics, stability superheavy elements, and fundamental theory neutrino interactions. At the same time, there have important developments on conceptual computational level for theory. The promising theoretical avenues were subject workshop held at University York October 2019; this report summarises findings recommendations.
Collective inertia is strongly influenced at the level crossing which quantum system changes diabatically its microscopic configuration. Pairing correlations tend to make large-amplitude nuclear collective motion more adiabatic by reducing effect of those configuration changes. Competition between pairing and thus expected have a profound impact on spontaneous fission lifetimes. To elucidate role nucleonic fission, we study dynamic trajectories $^{264}$Fm $^{240}$Pu using state-of-the-art...
In this letter, we outline a methodology to calculate microscopically mass and charge distributions of spontaneous fission yields. We combine the multi-dimensional minimization collective action for with stochastic Langevin dynamics track relevant paths from ground-state configuration up scission. The nuclear potential energy inertia governing tunneling motion are obtained density functional theory in space shape deformations pairing. obtain quantitative agreement experimental data find that...
The spontaneous fission lifetime of 264Fm has been studied within nuclear density functional theory by minimizing the collective action integral for in a two-dimensional quadrupole space representing elongation and triaxiality. potential inertia tensor are obtained self-consistently using Skyrme energy density-dependent pairing interaction. resulting lifetimes compared with static result minimum-energy pathway. We show that pathways strongly depend on assumptions underlying inertia. With...
According to theory, cluster radioactivity becomes an important decay mode in superheavy nuclei. In this work, we predict that the strongly-asymmetric fission, or emission, is fact dominant fission channel for $^{294}_{118}$Og$_{176}$, which currently heaviest synthetic isotope known. Our theoretical approach incorporates features of dynamics, including quantum tunneling and stochastic dynamics up scission. We show that, despite appreciable differences static properties such as barriers...
Fragment mass distributions from fission of the excited compound nucleus 178Pt have been deduced measured fragment velocities. The was created at JAEA tandem facility in a complete fusion reaction 36Ar + 142Nd, beam energies 155, 170 and 180 MeV. data are indicative mixture mass-asymmetric mass-symmetric modes associated with higher lower total kinetic fragments, respectively. yields dominated by asymmetric splits, symmetric mode contributing level ≈1/3. This constitutes first observation...
The goal of this paper is to better understand the structure fission fragment distributions by investigating competition between static collective manifold and stochastic dynamics. In particular, we study characteristics tails yield distributions, which correspond very asymmetric fission. We use Langevin framework simulate nuclear evolution after system tunnels through multi-dimensional potential barrier. For a representative sample different initial configurations along outer turning-point...
We systematically analyse the nuclear moments of inertia determined within Skyrme and Gogny density-functional theories. The time-odd mean fields generated by collective rotation are self-consistently an exact iterative solution adiabatic time-dependent Hartree-Fock-Bogoliubov (ATDHFB) equations. Although details results depend on functional used, calculated in good overall agreement with experimental data, no adjustable parameters. To show essential importance fields, ATDHFB compared those...
An iterative adiabatic time-dependent Hartree–Fock–Bogoliubov (ATDHFB) method is developed within the framework of Skyrme density functional theory. The ATDHFB equation solved iteratively to avoid explicitly calculating stability matrix. contribution time-odd mean fields ATDHF(B) moment inertia incorporated self-consistently, and results are verified by comparing them with dynamical cranking predictions. mass tensor calculated density-derivative term evaluated numerical differentiation....
Pre-scission neutron multiplicities from fission of the compound nuclei ${}^{210,212,214,216}$Rn have been measured in order to investigate $N/Z$ dependence hindrance. The Rn isotopes are populated through fusion ${}^{16,18}$O $+$ ${}^{194,198}$Pt systems and formed at four excitation energies range 50--79 MeV. experimental pre-scission yield is compared with predictions statistical model nuclear decay containing strength dissipation as a free parameter. obtained present analysis does not...
Pre- and post-scission neutron multiplicities are measured for the three isotopes of Fr (${}^{217}$Fr, ${}^{215}$Fr, ${}^{213}$Fr) in excitation energy range 48--91.8 MeV. Out these isotopes, ${}^{213}$Fr has shell closure (${N}_{C}=126$) while other two non-closed-shell nuclei. Statistical model calculations using Kramers' fission width performed to investigate effects on dissipation strength which fit experimental data. It is observed that correction binding energies evaporated particles...
Background: A quantitative microscopic understanding of the fission-fragment yield distributions represents a major challenge for nuclear theory as it involves intricate competition between large-amplitude collective motion and single-particle nucleonic motion. Purpose: recently proposed approach to global modeling fission fragment is extended account odd-even staggering in charge yields neutron evaporation. Method: Fission trajectories are obtained within density functional framework,...
A statistical model calculation for the decay of a compound nucleus is presented where nuclear spin dependence Kramers modified fission width included. Specifically, dependences frequencies harmonic oscillator potentials osculating rotating liquid-drop potential at equilibrium and saddle regions are considered. Results $^{16}\mathrm{O}+^{208}\mathrm{Pb}$ system show that energy dissipation strength extracted from fitting experimental data substantially reduced when properly taken into account.
Evaporation residue cross sections for the reaction ${}^{16}\text{O}+{}^{194}\text{Pt}$ were measured at beam energies in range 75.4--103.1 MeV using gas-filled separator Hybrid Recoil Mass Analyzer Inter University Accelerator Centre, New Delhi. The transmission efficiency of was obtained calibration system ${}^{16}\text{O}+{}^{184}\text{W}$ and a Monte Carlo simulation code. Measured evaporation fitted with statistical model calculations Kramers' formula. present measurement provides...
Experimental measurements of evaporation residue (ER) cross sections for the $^{19}F$ + $^{194,196,198}\mathrm{Pt}$ reactions forming $^{213,215,217}\mathrm{Fr}$ compound nuclei are reported. The measured at beam energies in range 101--137.3 MeV. survival probability $^{213}\mathrm{Fr}$ nucleus with neutron number $N=126$ is found to be lower than probabilities $^{215}\mathrm{Fr}$ and $^{217}\mathrm{Fr}$ numbers $N=128$ 130 respectively. Statistical model analysis ER show that an excitation...
Evaporation residue cross sections for $^{19}\mathrm{F}+^{184}\mathrm{W}$ have been measured at beam energies in the range of 90--130 MeV using Heavy Ion Reaction Analyzer Inter University Accelerator Centre. A new approach, based on Monte Carlo calculations, has adopted estimating evaporation (ER) transmission efficiency. The challenges detection ERs caused by presence isomeric states with longer half-lives thoroughly discussed. Measured fitted statistical model calculations treating...
We examine the validity of extending Kramers' expression for fission width to systems with shape-dependent dissipations. For a system dissipation, obtained presaddle dissipation strength is found be different from stationary corresponding Langevin equations. It demonstrated that probability hot compound nucleus undergoing depends on both and postsaddle dynamics collective nuclear motion. The predictions prescission neutron multiplicity evaporation residue cross section statistical model...
The fragment mass distribution from fission of hot nuclei is studied in the framework two-dimensional Langevin equations. asymmetry coordinate obtained dynamical calculation both at saddle and scission regions order to investigate role saddle-to-scission dynamics distribution. Statistical model predictions distributions are also compared with results. Results for a number covering broad range distances presented.
The prescission neutron multiplicity excitation function is measured for the first time three isotopes across a major closed shell in order to investigate effects on fission hindrance. Three of Fr (${}^{213,215,217}$Fr) are populated by fusion ${}^{19}\mathrm{F}{+}^{194,196,198}$Pt energy range 46.6--91.8 MeV. While ${}^{213}$Fr has closure at $N=126$, ${}^{215}$Fr and ${}^{217}$Fr away from shell. It found statistical model analysis experimental data that strengths nuclear dissipation...
Background: More than half of all the elements heavier iron are made by rapid neutron capture process (or $r$ process). For very-neutron-rich astrophysical conditions, such at those found in tidal ejecta stars, nuclear fission determines $r$-process endpoint, and fission-fragment yields shape final abundances $110\ensuremath{\le}A\ensuremath{\le}170$ nuclei. The knowledge hundreds nuclei inhabiting regions landscape is thus crucial for modeling heavy-element nucleosynthesis.Purpose: In this...
Background: Synthesis of a doubly magic spherical nucleus beyond ${}_{82}^{208}$Pb${}_{126}$ is key question in contemporary nuclear physics. Such nuclei can exist solely because shell stabilization. As the formation cross section super heavy elements prohibitively low, attempts have been made to understand stabilizing effects closed proton ($Z$) and neutron ($N$) shells vicinity ${}_{82}^{208}$Pb${}_{126}$.Purpose: The present work elucidate effect closure, general, same $Z=82$,...
Mass distribution of fission fragments and neutron multiplicity in the ${}^{16}\text{O}+{}^{238}$U reaction were measured at near- below-barrier energies. A sudden change fragment mass width, observed present measurement, confirmed transition to quasifission energies; same was indicated earlier from study angular anisotropy. However, measurement prescission as well evaporation residue yield did not indicate any significant departure respective statistical model predictions throughout energy...
The phenomenon of collective enhancement in nuclear level density and its fadeout has been probed using neutron evaporation study two strongly deformed (173Lu, 185Re), one spherical (201Tl) compound nuclei over the excitation energy (E⁎) range ∼22–56 MeV. Clear signature was observed for first time both residues 172Lu 184Re at an ∼14–21 Calculations based on finite temperature functional theory, as well macroscopic–microscopic shape transition model, have established a close correlation...