Speaker
Prof.
Norbert Pietralla
(IKP, Technische Universität Darmstadt)
Description
Considerable efforts are currently being made to improve our understanding of
the structural evolution of heavy nuclei, in particular, those with neutron
excess. This evolution as a function of nucleon number is dictated by the
dynamics of the valence shell. Since quantitative theoretical predictions from
first principles are not yet possible, experimental constraints and input on key
quantities, such as the proton-neutron quadrupole-quadrupole interaction, are
highly desirable. The proton-neutron interaction in the nuclear valence shell
dominates the formation of collective structures at low excitation energy, e.g.,
nuclear quadrupole deformation. The properties of proton-neutron non-
symmetric excitation modes of the valence shell, so-called mixed-symmetry
states (MSSs), are particularly sensitive to certain parts of the effective valence-
shell interaction. MSSs of stable nuclei have, therefore, been studied for over
20 years with electron-, photon-, and neutron-scattering reactions. We have
recently demonstrated [1,2] a technique for investigating MSSs based in
Coulomb excitation reactions in inverse kinematics, a method applicable to
neutron-rich radioactive ion beams. MSSs in vibrational nuclei such as 96Ru and
138Ce near N=50 and 82 neutron shell closures have been studied with this
method. We will give an overview over these results and we will address the
potential research on MSSs with modern RIBs.
[1] N. Pietralla et al., Phys. Rev. C 64, 031301(R) (2001).
[2] G. Rainovski et al., Phys. Rev. Lett. 96, 122501 (2006).
Primary author
Prof.
Norbert Pietralla
(IKP, Technische Universität Darmstadt)
