Transport properties of isospin asymmetric nuclear matter using the time-dependent Hartree-Fock method

Abstract

Background: The study of deep-inelastic reactions of nuclei provide a vehicle to investigate nuclear transport phenomena for a full range of equilibration dynamics. These inquires provide us the ingredients to model such phenomena and help answer important questions about the nuclear Equation of State (EOS) and its evolution as a function of neutron-to-proton (N/Z) ratio.Purpose: The motivation is to examine the real-time dynamics of nuclear transport phenomena and its dependence on (N/Z) asymmetry from a microscopic point of view to avoid any pre-conceived assumptions about the involved processes.Method: Time-dependent Hartree-Fock (TDHF) method in full 3D is employed to calculate deep-inelastic reactions of 78 Kr+ 208 Pb and 92 Kr+ 208 Pb systems at 8.5 MeV/A. The impact parameter and energy-loss dependence of relevant observables are calculated. In addition, density constrained TDHF method is used to compute excitation energies of the primary fragments. The statistical deexcitation code GEMINI is utilized to examine the final reaction products.Results: The kinetic energy loss and sticking times as a function of impact parameter are calculated. Final properties of the fragments (charge, mass, scattering angle, kinetic energy) are computed. Their evolution as a function of energy loss is studied and various intra-relations are investigated. The fragment excitation energy sharing is computed. Conclusions:We find a smooth dependence of the energy loss, E loss , on the impact parameter for both systems. On the other hand the transfer properties for low E loss values are very different for the two systems but become similar in the higher E loss regime. The mean life time of the charge equilibration process, obtained from the final (N − Z)/A value of the fragments, is shown to be ∼ 0.5 zs. This value is slightly larger (but of the same order) than the value obtained from reactions at Fermi energies.

Dynamic description of ternary and quaternary splits of heavy nuclear systems in the deep-inelastic regime

“…We take the intervals b = [5,6] and b = [9, 10] fm as representative for 'semi-central' and 'semi-peripheral' collisions, respectively. Similarly to the simulation strategy used in Ref.…”

“…The three upper rows of Fig. 5 select three representative events illustrating the most probable outcome for the interval b = [5,6] fm. Independently of the number of fragments in the exit channel, these configurations tend to drive matter sideward, so that a disk forms along the reaction plane and, eventually, matter distributes around a hollow, while two denser bulges develop around the PLF and TLF positions.…”

Quasifission Dynamics in Microscopic Theories

“…Recently, time-dependent Hartree-Fock (TDHF) theory have proven to be an excellent tool for studying QF dynamics, and in particular mass-angle distributions and final fragment total kinetic energies (TKE) [48,31,37,49,32,50,51,52,34,53,45,54,55,56]. While the fragments produced in TDHF studies are the excited primary fragments [57] a number of extensions based on the use of Langevin dynamics have been successfully applied to de-excite these fragments [55,58,59,56,60] Theoretical studies of quasifission dynamics have taught us that dynamics themselves may be dominated by shell effects [61,47]. Despite the apparent strong differences between fission and quasifission, it is interesting to note that similar shell effects are found in both mechanisms [54].…”

Exploring Zeptosecond Quantum Equilibration Dynamics: From Deep-Inelastic to Fusion-Fission Outcomes in Ni58+Ni60Williams1, Sekizawa2, Hinde3 et al. 2018Phys. Rev. Lett.Self Cite455550View full textAdd to dashboardCite

“…Through the manipulation of collision entrance channel parameters (projectile-target combinations and energies), a range of factors with the potential to affect energy dissipation can be explored. Typical timescales for energy dissipation in such systems could in principle vary from isospin and mass equilibration times on the order of 0.3-0.5 zs [14,15] and ∼5 zs [16,17], respectively.In nuclear reactions, the observation of the total kinetic energy of the reaction products (TKE) offers a direct measure of energy dissipation. The observation of the masses of reaction products via direct or indirect methods offers a measure of system equilibration in a key degree of freedom, and can be used to explore fluctuations in reaction product masses as a function of TKE.…”

“…Through the manipulation of collision entrance channel parameters (projectile-target combinations and energies), a range of factors with the potential to affect energy dissipation can be explored. Typical timescales for energy dissipation in such systems could in principle vary from isospin and mass equilibration times on the order of 0.3-0.5 zs [14,15] and ∼5 zs [16,17], respectively.…”