Tübingen 2003 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 40: Theorie VI
HK 40.10: Vortrag
Donnerstag, 20. März 2003, 15:45–16:00, D
QRPA multi-phonon description of low energy dipole excitations in neutron rich nuclei — •N. Tsoneva1,2, H. Lenske1, and Ch. Stoyanov2 — 1Institut für Theoretische Physik, Universität Giessen — 2Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgarien
The properties of the low lying 1− pygmy resonance
excitations in neutron rich exotic nuclei are studied by HFB and
QRPA theory. Our special emphasis is to investigate the dependence
of the fragmentation pattern of the dipole strength function on
the neutron excess. As a general result, found e.g. in the tin
isotopes, an interesting correlation of the pygmy resonance
strength and the size of the neutron skin is obtained. Our calculations
confirm previous experimental findings that the lowest 1− strength
includes strong quadrupole-octupole two-phonon components.
Dipole and other multipole strength distributions are discussed for the
Sn and Ni isotopic chains, including exploratory investigations for the
experimentally unknown regions. Of particular interest is the
influence of the GDR on the B(E1;0+ → 11−) and
B(E1;31− → 21+) transition probabilities. The use
of HFB mean-field potentials and s.p. energies is found to
provide a reliable extrapolation into the region far off
stability.
Supported in part by DFG grant Le439/5 and
European Graduate School Giessen-Copenhagen.