Excitation and Probing of the 229Th Nuclear Isomer at Storage RingsONLINE ONLY

229Th with a low-lying nuclear isomeric state at about 8eV is an essential candidate for building a nuclear clock and testing fundamental physics. However, the isomeric-state energy has not been determined with a high precision, and laser excitation of the isomeric state has not been realized yet. In this talk, we will explore laser excitation of relativistic 229Th ions in storage rings, taking advantage of the tunability of both the laser-beam and ion-bunch parameters [1,2]. Importantly, the expected mixing of nuclear states in highly charged 229Th ions (see, for instance, Ref.[3]) is exploited. In the direct resonant excitation scenario, the significantly reduced isomeric-state lifetime in H- or Li-like 229Th ions would correspond to much higher excitation rates compared to bare thorium nuclei [4]. Furthermore, the mixing opens electric dipole transitions that change both the electronic and nuclear states. This would allow for efficient nuclear isomer excitation via an electronic excited state in Li-like 229Th ions. We will also talk about schemes for probing the isomeric state, using either nuclear or electronic transitions, which can help determine the isomeric-state energy with a significantly higher precision compared to the current value.

[1] D. Budker, J. C. Berengut, V. V. Flambaum, M. Gorchtein, J. Jin, F. Karbstein, M. W. Krasny, Y. A. Litvinov, A. Pálffy, V. Pascalutsa, A. Petrenko, A. Surzhykov, P. G. Thirolf, M. Vanderhaeghen, H. A. Weidenmüller, and V. Zelevinsky, Annalen der Physik, 2100284 (2022)
[2] J. Jin, H. Bekker, T. Kirschbaum, Y. A. Litvinov, A. Pálffy, J. Sommerfeldt, A. Surzhykov, P. G. Thirolf, and D. Budker (arXiv:2208.05042)
[3] V. M. Shabaev, D. A. Glazov, A. M. Ryzhkov, C. Brandau, G. Plunien , W. Quint, A. M. Volchkova, and D. V. Zinenko, Phys. Rev. Lett. 128, 043001 (2022)
[4] C. Brandau, Towards Storage Ring Studies of Highly Charged 229Th (AP-Seminare, https://indico.gsi.de/event/11567/) (2020)