Fusion-fission and quasifission of superheavy systems withZ=110–116formed inCa48-induced reactions

Abstract

Background:In heavy-ion-induced reactions the mechanism leading to the formation of the compound nucleus and the role of quasifission is still not clear. Purpose: Investigation of the quasifission process of superheavy composite systems with Z = 110-116 and comparison with properties of fusion-fission and quasifission of lighter composite systems. Method: Mass and energy distributions of fissionlike fragments formed in the reactions 48 Ca + 232 Th, 238 U, 244 Pu, and 248 Cm at energies near the Coulomb barrier have been measured using the double-arm time-of-flight spectrometer CORSET at the U-400 cyclotron of the FLNR JINR. Results: The most probable fragment masses as well as total kinetic energies and their dispersions in dependence on the interaction energies and ion-target combinations have been studied for asymmetric and symmetric fragments formed in the reactions. The capture cross sections were obtained for the reactions 48 Ca + 244 Pu and 248 Cm. The lower limits for fission barriers of 283−286 Cn, 289−292 Fl, and 293−296 Lv compound nuclei were estimated. Conclusions: Analysis of the properties of symmetric fragments has shown that a significant part of these fragments may be attributed to fusion-fission process for the reactions 48 Ca+ 238 U, 244 Pu, and 248 Cm.

Investigation of fusion probabilities in the reactions with Cr52,54, Ni64 , and Novikov1, Козулин2, Knyazheva3 et al. 2020Phys. Rev. CSelf Cite27110View full textAdd to dashboardCite

“…The mass-energy distributions for the reactions with 52,54 Cr are similar to those of the reactions of 48 Ca with actinide target nuclei [16]. The pronounced asymmetric QF component with heavy fragments in the vicinity of the double magic lead is clearly observed.…”

“…The evaluation of the CN fission contribution to all fissionlike fragments based on the analysis of the TKE distribution of symmetric fragments formed in heavy-ion-induced reactions was applied in Refs. [14][15][16][17][18]. This approach allows the experimental estimation of the upper limit of the fusion probability P CN .…”

Cluster radioactivity in superheavy nuclei

“…The same mechanism invoked here for spontaneous fission applies also to fusion-fission and quasifission observed in this region of SH nuclei [39][40][41][42][43]. In all the reactions the possible fragment mass asymmetry is forced by the shell structure of 208 Pb.…”

Colloquium : Superheavy elements: Oganesson and beyond

“…An interesting, albeit yet experimentally unexplored, decay mode of superheavy nuclei is cluster radioactivity. This phenomenon, first observed in 1984 (Rose and Jones, 1984) as the emission of 14 C from 223 Ra, has since been confirmed in a number of heavy nuclei with Z > 86, which decay by emitting light clusters between 14 C and 34 Si, as well as in superheavy nuclei with Z ≤ 116 (Itkis et al, 2015;Kozulin et al, 2014). For superheavy nuclei with Z ≥ 118, cluster radioactivity is expected to become competitive with alpha decay and spontaneous fission (Poenaru and Gherghescu, 2018;Poenaru et al, 2011Poenaru et al, , 2012Poenaru et al, , 2013Poenaru et al, , 2015Santhosh and Nithya, 2018a;Zhang and Wang, 2018).…”