Deformed shell effects in 48Ca + 249Bk quasifission fragments

Background: Quasifission is the main reaction channel hindering the formation of superheavy nuclei (SHN). Its understanding will help to optimize entrance channels for SHN studies. Quasifission also provides a probe to understand the influence of shell effects in the formation of the fragments. Purpose: Investigate the role of shell effects in quasifission and their interplay with the orientation of the deformed target in the entrance channel. Methods: Ca-48 + Bk-2(49) collisions are studied with the time-dependent Hartree-Fock approach for a range of angular momenta and orientations. Results: Unlike similar reactions with a U-238 target, no significant shell effects which could be attributed to the Pb-208 doubly magic nucleus are found. However, the octupole deformed shell gap at N = 56 seems to strongly influence quasifission in the most-central collisions. Conclusions: Shell effects similar to those observed in fission affect the formation of quasifission fragments. Mass-angle correlations could be used to experimentally isolate the fragments influenced by N = 56 octupole shell gaps.