Nuclear levels in 228Th populated in the decay of 228Pa (II)
T. Weber1 - J. de Boer2 - K. Freitag1 - J. Gröger1 - C. Günther1 - P. Herzog1 - V.G. Soloviev3 - A.V. Sushkov3 - N.Yu. Shirikova3
1 Institut für Strahlen- und Kernphysik, Universität Bonn, Nussallee 14-16,
D-53115 Bonn, Germany
2 Sektion Physik, Universität München, Am Coulombwall 1, D-85748 Garching, Germany
3 Bogolubov Laboratory of Theoretical Physics, Joint Institute of Nuclear Research, 141980
Dubna, Russia
Received: 30 March 1998 Communicated by D. Schwalm
Abstract
The electron-capture decay of 228Pa to levels in 228Th was studied
using mass-separated sources and a -ray detection system consisting of
five Compton-suppressed Ge detectors. A total of 87 levels were observed up to
an excitation energy of 2 MeV which are connected by approximately 500
-ray transitions. The complete
octupole quadruplet, three excited
bands and two
bands were identified below 1.4 MeV. The observed level structure is compared
to calculations within the quasiparticle-phonon nuclear model. The
surprisingly good agreement indicates that 228Th has less transitional
character than hitherto assumed.
PACS
23.20.-g Electromagnetic transitions -
21.60.Jz Hartree-Fock and random-physe approximations -
27.90.+b
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