R. du Rietz

Influence of entrance-channel magicity and isospin on quasi-fission

The role of spherical quantum shells in the competition between fusion and quasi-fission is studied for reactions forming heavy elements. Measurements of fission fragment mass distributions for different reactions leading to similar compound nuclei have been made near the fusion barrier. In general, more quasi-fission is observed for reactions with non-magic nuclei. However, the

Effects of Nuclear Structure on Quasi-fission

^{40}

Construction and performance of the PHENIX pad chambers

Ca+

Dynamics and Time-scales in Breakup and Fusion

^{208}

Effects of Nuclear Structure in Heavy Element Formation Dynamics

Pb reaction is an exception, showing strong evidence for quasi-fission, though both nuclei are doubly magic. Time-dependent Hartree-Fock calculations predict fast equilibration of

Investigating quasi-fission dynamics through mass-angle distributions

N/Z

Comprehensive {gamma}-ray spectroscopy of rotational bands in the N=Z+1 nucleus {sup 61}Zn

in the two fragments early in the collision. This transfer of nucleons breaks the shell effect, causing this reaction to behave more like a non-magic one in the competition between fusion and quasi-fission. Future measurements of fission in reactions with exotic beams should be able to test this idea with larger

Characterization of superdeformed bands in {sup 62}Zn

N/Z

Fission and quasi-fission: insights into heavy element formation reactions

asymmetries.

Two Distinct Quasifission Modes in the {sup 32}S+{sup 232}Th Reaction

The quasi-fission mechanism hinders fusion of heavy systems because of a mass flow between the reactants, leading to a re-separation of more symmetric fragments in the exit channel. A good understanding of the competition between fusion and quasi-fission mechanisms is expected to be of great help to optimize the formation and study of heavy and superheavy nuclei. Quantum microscopic models, such as the time-dependent Hartree-Fock approach, allow for a treatment of all degrees of freedom associated to the dynamics of each nucleon. This provides a description of the complex reaction mechanisms, such as quasi-fission, with no parameter adjusted on reaction mechanisms. In particular, the role of the deformation and orientation of a heavy target, as well as the entrance channel magicity and isospin are investigated with theoretical and experimental approaches.