München 2019 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 50: Structure and Dynamics of Nuclei X
HK 50.3: Vortrag
Donnerstag, 21. März 2019, 14:45–15:00, HS 16
Magnetic dipole moment predictions for 229Th — •Adriana Pálffy1 and Nikolay Minkov1,2 — 1Max-Planck-Institut für Kernphysik, Heidelberg, Germany — 2Institute of Nuclear Research and Nuclear Energy, Sofia, Bulgaria
The 229Th actinide isotope has a I=3/2 isomeric state lying only 7.8 eV above the ground state. This extremely small energy renders for the first time a nuclear transition accessible to vacuum ultraviolet lasers. Novel applications such as a nuclear frequency standard with unprecedented accuracy based on this transition are anticipated.
A recent laser spectroscopy experiment [1] has determined for the first time the magnetic dipole moment of the isomeric state. The measured value differs by a factor of approx. 5 from previous nuclear theory predictions based on the Nilsson model, raising questions about our understanding of the underlying nuclear structure. Here, we present a new theoretical prediction based on a nuclear model with coupled collective quadrupole-octupole and single-particle motions. Our calculations yield an isomer magnetic dipole moment of µ IS= −0.35µN in surprisingly good agreement with the experimentally determined value of −0.37(6)µN, while overestimating the ground state dipole moment by a factor 1.4 [2]. The model provides further information on the states’ parity mixing, the role and strength of the Coriolis mixing and the most probable value of the gyromagnetic ratio gR and its consequences for the transition probability B(M1).
[1] J. Thielking et al., Nature (London)
556, 321 (2018).
[2] N. Minkov and A. Pálffy, arXiv:1812.03921 [nucl-th] (2018).