  Quantum shell effects drive many aspects of many-body quantal systems and
their interactions. Among these are the quasifission reactions that impede the
formation of a compound nucleus in superheavy element (SHE) searches. Fragment
production in quasifission is influenced by shell effects as a nontrivial
manifestation of microscopic dynamics hindering the full equilibration of the
composite system to form the compound nucleus. In this Letter, we use the
microscopic time-dependent Hartree-Fock (TDHF) theory to study 48Ca+249Bk
collisions to investigate the influence of the tensor component of the
effective nucleon-nucleon interaction. The results show that the inclusion of
the tensor force causes the spherical shell effect to become more prominent,
particularly for the neutron number yield whose peak is exactly at magic number
N = 126. This suggests that the tensor force plays a compelling role in the
evolution of dynamical shell effects in nuclear reactions, influencing the
competition between spherical and deformed shell gaps.
