Bochum 2018 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 25: Structure and Dynamics of Nuclei V
HK 25.3: Vortrag
Dienstag, 27. Februar 2018, 17:15–17:30, HZO 80
Reduced transition probabilities for the gamma decay of the 7.8 eV isomer in 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 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.
In this work we predict the reduced magnetic dipole and electric quadrupole transition probabilities for the radiative decay of the 229Th 7.8 eV isomer to the ground state within a detailed nuclear-structure model approach. We show that the presence and decay of this isomer can only be accounted for by the Coriolis mixing emerging from a remarkably fine interplay between the coherent quadrupole-octupole motion of the nuclear core and the single-nucleon motion within a reflection-asymmetric deformed potential [1]. The predicted magnetic dipole transition probability which determines the radiative lifetime of the isomer is considerably smaller than presently estimated. The so-far disregarded electric quadrupole component may have non-negligible contributions to the internal conversion channel. These findings support new directions in the experimental search of the 229Th transition frequency for the development of a future nuclear frequency standard.
[1] N. Minkov and A. Pálffy, Phys. Rev. Lett. 118, 212501 (2017).