The production and first observation of ion beams of Ac, Np, and Pu at ISOLDE were significant milestones of LISA. Ac was successfully extracted as molecular fluoride ion beam (AcF⁺), enabling their first study through laser spectroscopy. Upgrades at ISOLDE's Offline 2 mass separator allowed detailed studies of molecular formation. Additionally, molecular actinide ion beams like AcF⁺ and AcFF⁺ were produced, broadening the scope of experimental studies on actinides and their applications in nuclear research and medicine.
High-resolution in-source laser spectroscopy using PI-LIST at ISOLDE enabled precise hyperfine structure analysis of Ac isotopes, advancing nuclear structure research. This method expanded the possibilities for studying rare isotopes and was complemented by its application to lanthanides. The technique set the stage for ongoing experimental campaigns and further exploration of actinides.
At GANIL, through strong collaboration with facilities like KUL, in-gas-jet laser spectroscopy was optimized, achieving high resolution for actinide research. Offline commissioning of the S3-LEB setup included developing high-performance Ti:Sapphire lasers with resolutions below 300 MHz, optimizing ion beam transmission to 80%. Breakthroughs in gas jet design enabled high-resolution studies at GSI, culminating in a 5-fold resolution improvement for No-isotopes. These efforts validated setups for future heavy element research.
Laser technology innovations, such as intra-cavity frequency tripling in Ti:Sapphire lasers and the development of the HighPower C-WAVE OPO, significantly improved laser spectroscopy capabilities. Collaborative campaigns using the C-WAVE system at the university of Mainz, measured elements like Np and Fm, achieving unprecedented precision in spectral measurements. These advancements facilitated research on nuclear properties and isotope production.
Efficient ionization schemes for 10 of the 15 actinide elements were developed, aiding ultra-trace analysis of radiotoxic isotopes and supporting theoretical models of complex atomic systems. Collaboration between theory and experiment improved understanding of hyperfine fields and level structures. Despite challenges, studies on actinide anions and negative ion spectroscopy remain a priority for future research.
The production and use of 225Ac for TAT expanded, with a second supply-line established at CERN MEDICIS. This development supported PRISMAP projects and identified inconsistencies in nuclear data, prompting a new experimental campaign at the ISOLDE Decay Station, with measurements foreseen in 2024.
LISA techniques extended beyond actinides to elements like Sr and Cs, aiding the analysis of nuclear fuel particulates and incidents like Chernobyl. These investigations provided insights into reactor behavior and radioactive releases, contributing to nuclear safety and environmental understanding.
WP5 of LISA focused on refining techniques for atomic spectroscopy and production of heavy actinide samples. Key achievements included molecular plating of 239Pu recoil sources, hyperfine parameter measurements for 235U, and advancements in gas jet systems for spectroscopy at facilities like GANIL and GSI.
Efforts to study lawrencium (Z=103) using the RADRIS method made significant progress, improving ion transport and detection efficiency. Although no resonances have been observed, larger search regions were excluded. The improved RADRIS technique allowed access to previously unreachable Fm isotopes, with findings published in Nature in 2024.
