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Quasifission is the primary reaction mechanism that limits the formation of superheavy nuclei and consequently an important ingredient for choosing the best target-projectile combinations for the heavy element searches. Quasifission is…

Nuclear Theory · Physics 2015-11-13 A. S. Umar , V. E. Oberacker , C. Simenel

The momentum transfer between the normal components to an index direction in the collision of an atom with a periodic surface is investigated. For fast atoms with grazing angle of incidence there is an interval of azimuthal angles around…

Quantum Physics · Physics 2009-05-05 Antonia Ruiz , Jose P. Palao , Eric J. Heller

The origin of the asymmetry in the fragment mass distribution of low-energy nuclear fission is considered from the semiclassical point of view. Using the semiclassical periodic-orbit theory, one can define and quantify the shell effect…

Nuclear Theory · Physics 2020-01-06 K. Arita , T. Ichikawa , K. Matsuyanagi

Nuclear fission presents a unique example of quantum entanglement in strongly interacting many-body systems. A heavy nucleus can split into hundreds of combinations of two complementary fragments in the fission process. The entanglement of…

Nuclear Theory · Physics 2024-08-15 Yu Qiang , Junchen Pei , Kyle Godbey

Nucleon exchange mechanism is investigated in the central collisions of ${}^{40}$Ca + ${}^{238}$U and ${}^{48}$Ca + ${}^{238}$U systems near the quasi-fission regime in the framework of the Stochastic Mean-Field (SMF) approach. Sufficiently…

Nuclear Theory · Physics 2016-01-12 S. Ayik , B. Yilmaz , O. Yilmaz

For light and medium mass systems the capture cross-section may be considered to be the same as that for complete fusion, whereas for heavy systems leading to superheavy formations the evaporation residue cross-section is dramatically…

Nuclear Theory · Physics 2016-05-12 A. S. Umar , V. E. Oberacker , C. Simenel

In the search for superheavy elements quasifission reactions represent one of the reaction pathways that curtail the formation of an evaporation residue. In addition to its importance in these searches quasifission is also an interesting…

Nuclear Theory · Physics 2020-03-23 K. Godbey , A. S. Umar

In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. This…

Nuclear Theory · Physics 2015-06-04 Y. Aritomo , K. Hagino , K. Nishio , S. Chiba

Background: Fission modes in superheavy nuclei are expected to be impacted by quantum shell effects. Similar shell effects may be present in quasifission reactions, acting to hinder the mass equilibration process in heavy-ion collisions.…

Nuclear Theory · Physics 2023-06-07 Patrick McGlynn , Cedric Simenel

The anisotropy in the angular distribution of the fusion-fission and quasifission fragments for the $^{16}$O+$^{238}$U, $^{19}$F+$^{208}$Pb and $^{32}$S+$^{208}$Pb reactions is studied by analyzing the angular momentum distributions of the…

A theory of the competition between fusion and quasi-fission in a heavy fusing system is proposed, which is based on a master equation and the two-center shell model. Fusion and quasi-fission arise from a diffusion process in an ensemble of…

Nuclear Theory · Physics 2007-05-23 Alexis Diaz-Torres

The microscopic framework of time-dependent covariant density functional theory is applied to a systematic study of ternary quasifission in collisions of pairs of $^{238}$U nuclei. It is shown that the inclusion of octupole degree of…

Nuclear Theory · Physics 2024-02-23 D. D. Zhang , B. Li , D. Vretenar , T. Nikšić , Z. X. Ren , P. W. Zhao , J. Meng

Coulomb fission mechanism may take place if the maximum Coulomb-excitation energy transfer in a reaction exceeds the fission barrier of either the projectile or target. This condition is satisfied by all the reactions used for the earlier…

To disentangle the role of shell effects and dynamics, fission fragment mass distributions of $^{191}$Au, a nucleus in the newly identified island of mass asymmetric fission in the sub-lead region, have been measured down to excitation…

Fission of atomic nuclei often produces mass asymmetric fragments. However, the origin of this asymmetry was believed to be different in actinides and in the sub-lead region [A. Andreyev {\it et al.}, Phys. Rev. Lett. {\bf 105}, 252502…

Nuclear Theory · Physics 2019-11-06 Guillaume Scamps , Cédric Simenel

Fission fragment mass distribution has been measured from the decay of $^{246}$Bk nucleus populating via two entrance channels with slight difference in mass asymmetries but belonging on either side of the Businaro Gallone mass asymmetry…

Background: Synthesis of superheavy elements (SHE) with fusion-evaporation reactions is strongly hindered by the quasifission (QF) mechanism which prevents the formation of an equilibrated compound nucleus and which depends on the structure…

Nuclear Theory · Physics 2016-06-03 A. S. Umar , V. E. Oberacker , C. Simenel

Some nearly-symmetric fusion reactions are systematically investigated with the improved quantum molecular dynamics (ImQMD) model. By introducing two-body inelastic scattering in the Fermi constraint procedure, the stability of an…

Nuclear Theory · Physics 2015-11-05 Ning Wang , Kai Zhao , Zhuxia Li

Multinucleon transfer (MNT) reactions offer a promising pathway to synthesize neutron-rich heavy nuclei, but the mechanism of inverse quasifission, as a key reaction channel of MNT, still remains not well understood. We employ…

Nuclear Theory · Physics 2026-03-13 Zhenji Wu , Xiang-Xiang Sun , Lu Guo

Quantum shell effects stabilising fission fragments with various shapes have been invoked as a factor determining the distribution of nucleons between the fragments at scission. Shell effects also induce asymmetric shapes in the nucleus on…

Nuclear Theory · Physics 2023-04-13 Rémi Bernard , Cédric Simenel , Guillaume Blanchon