Köln 2004 – wissenschaftliches Programm

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PV: Plenarvorträge

PV XX

PV XX: Plenarvortrag

Donnerstag, 11. März 2004, 11:30–12:00, P

Symmetry as a guiding principle in studying nuclear structure — •Nadya Smirnova — Department of Subatomic and Radiation Physics, University of Ghent, Ghent, Belgium

Symmetry and dynamical symmetry concepts play a fundamental role in quantum mechanics. In particular, they can greatly simplify the formulation and solution of the quantum many-body problems. We introduce the notations of dynamical symmetry and its breaking, and demonstrate how group-theoretical techniques can be used in providing analytically energy spectra and matrix elements of other physical operators on the example of the well-known symmetry versions of the nuclear shell model. Next, we consider the algebraic collective model of nuclear structure, describing the low-energy nuclear excitations in terms of interacting protonand neutron bosons. The model has been very successful in the description of experimental data and the prediction of new low-lying collective modes in nuclei, among which is the well-known scissors mode. As a recently developed extension, we discuss the proton-neutron version of the model, which incorporates quadrupole and octupole degrees of freedom. The application has been carried out to the describe the low-energy quadrupole-octupole colletivity in medium-mass near-spherical nuclei, including isovector excitations in the valence shell, multiphonon structures, and enhanced E1-transitions, which are intensively investigated in electron, photon and proton scattering experiments.