Speaker
Description
Actinide isotopes have been enjoying a renewed interest over the past few years due to evidence for rich nuclear structure evolution, in particular in the neutron-deficient region, where theoretical models predict the most pronounced reflection-asymmetric shapes, see e.g., [1]. In addition, the actinides host some unique cases in which state-of-the-art atomic and nuclear theoretical models are challenged in their predictive capabilities. This is the case for the two well-known low-energy isomers in $^{229}$Th and $^{235}$U.
Within the LISA~(Laser Ionization and Spectroscopy of Actinides) framework, a research program aimed towards the study of the nuclear structure of light actinide elements has been implemented at the IGISOL facility [2], University of Jyväskylä. The research focuses on the development of a range of production methods and the use of complementary spectroscopic techniques, including high-resolution laser spectroscopy, mass spectrometry, and $\alpha$/$\gamma$/$e^{-}$-decay spectroscopy. The former provides access to information such as the evolution of mean-square charge radii through the measurement of isotopic shifts in atomic transitions, in addition to nuclear electric quadrupole and magnetic dipole moments obtained via the atomic hyperfine structure [3]. Decay spectroscopy studies, on the other hand, provide a window to the measurement of decay modes and energies (Q values), branching ratio, half-lives, excited states, spins and parities and so forth, basic information that is often lacking in the region of interest.
This contribution will present an overview of the experimental effort at the IGISOL facility, reporting on the development towards high-resolution laser spectroscopy of the low-energy $^{235m}$U isomer, with a particular focus on the isomeric beam production [4]. In addition, the production and study of neutron-deficient actinide isotopes through the use of proton-induced fusion-evaporation reactions will be discussed. As a showcase, the result of a recent experiment using the new VADER spectroscopy station [5], dedicated to the study of decay properties in the region of interest, will be presented.
[1] Cao, Y. et al. "Landscape of pear-shaped even-even nuclei." Physical Review C 102.2 (2020): 024311.
[2] Moore, I. D. et al. "The IGISOL technique—three decades of developments." Three decades of research using IGISOL technique at the University of Jyväskylä: A Portrait of the Ion Guide Isotope Separator On-Line Facility in Jyväskylä (2014): 15-60.
[3] Campbell, P. et al. "Laser spectroscopy for nuclear structure physics." Progress in Particle and Nuclear Physics 86 (2016): 127-180.
[4] Reed, L. E. et al, contribution to the LISA Conference.
[5] Raggio, A. et al. "VADER: A novel decay station for actinide spectroscopy" Submitted to Nuclear Inst. and Methods in Physics Research, B (2023)
| Field | Exploring the limits of nuclear existence |
|---|---|
| Call for support | No |
