Systematic evidence for quasifission in Be9−, C12−, and O16 -induced reactions forming No258,260

2020

Zeptosecond contact times for element Z=120 synthesis

2020

The synthesis of new superheavy elements beyond oganesson (Z=118) requires fusion reactions with projectile nuclei with proton numbers larger than that of $^{48}$Ca (Z=20), which has been successfully employed for the synthesis of elements with Z=112-118. In such reactions, fusion is drastically hindered by fast non-equilibrated dynamical processes. Attempts to produce nuclei with Z=120 using the $^{64}$Ni+$^{238}$U, $^{58}$Fe+$^{244}$Pu, $^{54}$Cr+$^{248}$Cm, and $^{50}$Ti+$^{249}$Cf reactions have been made, which all result in larger Coulomb forces than for $^{48}$Ca-induced reactions, but no discovery has been confirmed to date. In this work, mass and angle distributions of fission frag…

Nuclear structure dependence of fusion hindrance in heavy element synthesis

2018

The production of the heaviest elements in fusion-evaporation reactions is substantially limited by very low cross sections, as fusion cross sections (including fusion-fission) are greatly reduced by the competing quasifission mechanism. Using the Australian National University Heavy Ion Accelerator Facility and CUBE detector array, fission fragments from the $^{48}\mathrm{Ti}+^{204,208}\mathrm{Pb}$ and $^{50}\mathrm{Ti}+^{206,208}\mathrm{Pb}$ reactions have been measured, with the aim to investigate how the competition between quasifission and fusion-fission evolves with small changes in entrance-channel properties associated mainly with the nuclear structure. Analysis of mass-distribution…

Mechanisms Suppressing Superheavy Element Yields in Cold Fusion Reactions.

2019

Superheavy elements are formed in fusion reactions which are hindered by fast nonequilibrium processes. To quantify these, mass-angle distributions and cross sections have been measured, at beam energies from below-barrier to 25% above, for the reactions of $^{48}\mathrm{Ca}$, $^{50}\mathrm{Ti}$, and $^{54}\mathrm{Cr}$ with $^{208}\mathrm{Pb}$. Moving from $^{48}\mathrm{Ca}$ to $^{54}\mathrm{Cr}$ leads to a drastic fall in the symmetric fission yield, which is reflected in the measured mass-angle distribution by the presence of competing fast nonequilibrium deep inelastic and quasifission processes. These are responsible for reduction of the compound nucleus formation probablity ${P}_{CN}$ …

Sensitive search for near-symmetric and super-asymmetric fusion-fission of the superheavy element Flerovium (Z=114)

2021

Physics letters / B 820, 136601 (2021). doi:10.1016/j.physletb.2021.136601