Speaker
Description
To better understand key nuclear properties, tremendous effort has been put into various theoretical models (eg. [1,2]), capable of reproducing experimental data with increasing accuracy. Benchmarking these models requires precise measurements of key nuclear observables, among which electromagnetic moments and charge radii play complementary roles. Laser Spectroscopy (LS) techniques allow one to measure all these quantities within a single experiment in an efficient and precise manner [3].
As an alternative to the well-established in-source and collinear LS methods, an offline beamline has been commissioned at KU Leuven to develop new spectroscopic methods to be implemented on trapped ions at Radioactive Ion Beam (RIB) facilities [4], complementing a pre-existing high-precision trap optimized for stable isotopes. This will substantially increase the laser-ion interaction time from a few microseconds to multiple seconds, ultimately limited only by the half-life of the radioactive ions. Via the excitation of weak transitions, such as radiofrequency transitions within a hyperfine manifold [5], electromagnetic moments beyond the electric quadrupole moment, like the magnetic octupole one, can be obtained. Therefore, another nuclear observable will be added as a benchmark for nuclear theory and provide information on the proton distribution inside the nucleus.
This contribution will give an overview of the project and present the latest results from our linear Paul trap, which includes the deceleration, trapping and laser cooling of Sr+ ions from 10 keV beam energy to below 10 mK temperature and the formation of Coulomb crystals. As an initial spectroscopic benchmark, the dipole-forbidden S1/2 → D5/2 transition was driven to quantify broadening mechanisms. Finally, the status of the ongoing installation of this setup at the IGISOL RIB facility [6] will be presented. The latter will enable both in-trap LS measurement of radioactive species and the preparation of ultra-cold ion bunches for Penning trap mass measurements [7].
References:
1. A. Ekstrom et al., Frontiers in Physics 11, 29094 (2023)
2. D. Bonatsos et al., Atoms 11(9), 117 (2023)
3. X. F. Yang et al., Progress in Particle and Nuclear Physics 129, 104005 (2023)
4. P. Imgram et al., Review of Scientific Instruments 96, 093302 (2025)
5. X. F. Yang et al., PRA 90, 052516 (2014)
6. I.D. Moore et al., Nuclear Instruments and Methods in Physics Research Section B 317, 208-213 (2013)
7. S. Sels et al., Physical Review Research 4, 033229 (2022)
| Academic level | PhD student |
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