The LISA Final conference is a gathering of the LISA MSCA innovative training network and beyond, started in 2019.
The LISA (Laser Ionization and Spectroscopy of Actinides) consortium has been training a new generation of experts in different fields of radioactive ion beam research and applications, with the underlying goal of improving our knowledge of the elements known as the actinides using laser spectroscopy techniques.
As the LISA project comes to an end, this conference will be the opportunity to showcase the work of the 15 early stage researchers (ESR) recruited.
Invited speakers from a variety of topics will also broaden the horizon:
A graduation ceremony will be held at the end of the Conference for the ESRs and Affiliates who would have obtained their PhD.
This conference will also be dedicated to Bruce Marsh, an accomplished & internationally known researchers among his peers, who acted as LISA Network Coordinator after initiating and brining together the network.
New Abstract deadline: Sunday 16 June
Registration Deadline: Sunday 7 July
Atomic and molecular actinide ion beams have been produced at the CERN-ISOLDE facility using the Isotope Separation On-Line (ISOL) technique. The ion beam composition was studied using: the ISOLTRAP Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF MS) for identification by ToF mass measurements, online γ-ray spectroscopy at the ISOLDE tape station, and off-line decay spectroscopy of ion-implanted samples.
This contribution presents offline commissioning experiments and results of the Super Separator Spectrometer-Low Energy Branch (S
-LEB) setup. S
-LEB is a low-energy radioactive ion beam facility, which will be employed for the study of exotic nuclei, under commissioning as a part of the GANIL-SPIRAL2 facility. For the offline commissioning of the S
-LEB set-up with laser ionization and spectroscopy, a gas cell based technique called in-gas jet laser spectroscopy was implemented which aims to provide the optimum resolution. Technical development including implementation of a narrowband continuous wave Ti: sapphire laser acting as a seed laser for in-gas-jet laser spectroscopy was implemented as a part of this work. The first laser spectroscopy results with the coupling of a buffer gas cell to the system is reported. For the commissioning tests, a tantalum filament was installed in the gas cell for the production of stable isotopes of Er,
Er being one of the online experiments foreseen. Characterization of the Er ions in the gas cell and jet has been performed to obtain the minimum possible spectral resolution and maximum ionization efficiency.
As humans, we are a mélange of diverse chemical elements: a fragile composition of oxygen, carbon, hydrogen, nitrogen, calcium, and others that hang in an improbable but finely tuned balance. Once this balance is disturbed, either due to a deficiency or excess of certain elements, it can lead to pathologies that have been linked to a variety of severe diseases such as cancer, Alzheimer’s Disease, or Parkinson’s Disease.
What if we could use our growing knowledge of different chemical elements, and the technologies applied in nuclear physics, to better understand how our bodies function, and why we get sick? How could we apply that knowledge to solve problems in our bodies?
Join me for my talk to learn about TRIUMF’s role in producing, studying, and applying isotopes of various chemical elements to understand the exact role of different metal ions in health and in disease. Delve into the little-known medical applications of nuclear physics techniques, such as beta-radiation detected nuclear magnetic resonance, and discover how an interdisciplinary approach can help us trace the origins of different diseases, as well as a synergistic endeavour to design and develop more efficient (radio)pharmaceuticals.
Studies of the atomic spectrum through resonant laser excitation provide access to the nuclear structures. Precise measurements of the interactions of the nuclear ground state with the electronic shell permit the extraction of nuclear properties which are closely related to the nucleus’ configuration and shape [1]. With atomic transitions of the valence electrons in the range of a few eV, these are accessible with lasers. However, this method is limited by the low production yields of the isotope of interest, a scarce knowledge on the atomic structure [2], and the capacity to produce the relevant wavelength.
For high-resolution laser spectroscopy, the optical linewidth must be low enough to resolve the atomic lines up to the hyperfine structure (HFS) but should not be much narrower than the resolution-limiting effect of the specific experimental setup to maximize the efficiency [3]. Depending on the spectroscopy technique in use, resonance peak linewidths can be as low as 40-70 MHz [4], sufficient to resolve the HFS in most elements. At the cost of rather challenging experimental setups, pulsed laser light with an optical linewidth of less than 50 MHz has been reported [5] by the amplification of a cw-dye laser in a pulsed dye amplifier (PDA), and of 20 MHz [6] by injection-locking a titanium:sapphire (Ti:Sa) with a narrow-linewidth cw-Ti:Sa. On the other hand, an optical parametric oscillator (OPO) seeded PDA system has demonstrated [7] comparable performance in the range near 330 nm with an optical linewidth in the order of 100 MHz, which will be presented in this work.
As more exotic nuclides are accessible, new laser techniques are needed to produce adequate wavelengths in notoriously challenging ranges, whilst maintaining power stability and optical narrow-band operation [8, 9, 10]. For instance with the off-line high-resolution spectroscopy studies on Fm-255, presented in this work, and performed at Mainz University, using the Perpendicularly Illuminated Laser Ion Source and Trap (PI-LIST) together with a diode pumped cw-Ti:sa injection-locked pulsed Ti:sa laser system. However, only two excitation schemes were available to reach due to the lack of a suitable narrow-band laser in the wavelength of interest outside of the cw-Ti:sa seed range. In this context, we propose in this work an all-solid-state system based on an OPO seeded optical parametric amplifier (OPA) to generate narrow-band, high-energy pulses for high-resolution laser ionization spectroscopy, in the range of 1000 nm to 1530 nm to be subsequently frequency doubled or tripled, in order to obtain the desired experimental wavelength.
Laser ionization and spectroscopy of actinides are among the primary research activities of the LARISSA group at Mainz University. Numerous isotopes have been investigated using resonant ionization mass spectrometry.
The research carried out at the RISIKO mass separator of Mainz University using the PI-LIST and the newly developed FI-LIST laser ion sources will be presented. The former allows for the measurement of hyperfine structures, while the latter enables the study of the ionization potential of elements exhibiting complex spectra. The results of the studies on neptunium, obtained using both sources, will be showcased during the presentation.
The project of Early Stage Researcher 6 (ESR06), originally set to measure the electron affinity of an actinide, had to be adapted due to unforeseen circumstances. During their secondment with the CRIS experiment at ISOLDE-CERN, 238U− was successfully produced via two consecutive electron capture reactions. These results led to the theoretical work of the ESR, where they computed electron capture cross-sections for bare ion collisions with hydrogen using the Crank-Nicolson
method. Having proven the method agrees with experiments and other theoretical models, they now plan on calculating actinide collisions. In Gothenburg, a high-precision method for measuring electron affinity values, applied to cesium and rubidium, showed applicability for francium and actinides. Stockholm studies using the DESIREE cryogenic storage ring demonstrated the manipulation of bound anionic states with lasers, also promising for actinide research. Overall, although photodetachment studies were delayed, the groundwork laid seems encouraging future work on actinide anions.
The study of the actinides represents a frontier in contemporary nuclear and atomic physics research. Lawrencium (Lr), with an atomic number of 103, is the heaviest and final actinide in the periodic table, positioned just before the super-heavy elements. Despite its significance, experimental data for lawrencium remain scarce. Precise and accurate theoretical calculations are essential for determining its energy levels.
Calculations were initially performed on lutetium (Lu), the lighter homologue of lawrencium, for which experimental data are available. This step is crucial to validate the predictive accuracy of our computational models for calculating the energy spectrum and transition properties of lawrencium.
The energy spectra of Lawrencium and Lutetium are investigated using the multiconfigurational Dirac-Hartree-Fock (MCDHF) method. Results of both the neutral atoms are presented and compared to previous calculations and experiment where available.
In this presentation, we report large-scale precision calculations of the energy structure of neutral lawrencium. Our results provide significantly more precise values than previous MCHF calculations for the energy levels of the levels and their corresponding transition rates.
Evidence of rich nuclear structure evolution has sparked renewed interest in the actinide region, prompting many research programs to study this area of the nuclide chart. Theoretical models predict the emergence of pronounced reflection-asymmetric shapes in the neutron-deficient isotopes of light actinide elements [1]. In addition, unique cases of interest are present such as the two well-known low energy isomers in
Th [2] and
U [3], the former proposed as a candidate for an optical based nuclear clock [4].
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 [5], University of Jyväskylä Accelerator laboratory JYFL-ACCLAB. The research focuses on two objectives, the former connected to the production and study of neutron deficient actinides employing proton-induced fusion-evaporation reactions and decay spectroscopy techniques, the latter to the development of an isomeric beam of
U and its measurement via collinear laser spectroscopy.
Laser spectroscopic techniques act as a bridge between nuclear and atomic physics, providing access to information including the evolution of mean-square charge radii through the measurement of isotopic shifts in atomic transitions, in addition to nuclear magnetic dipole and electric quadrupole moments via the measurement of hyperfine structure [6]. Decay spectroscopy studies, on the other hand, provide a window to the measurement of decay modes of nuclei, as well as energies (Q-values), branching ratios, half-lives, excited states, spins and parities and so forth, basic nuclear structure information that is surprisingly lacking in the region of interest.
This contribution will present an overview of the experimental effort at the IGISOL facility, reporting on the results achieved during the LISA project, in addition to the outlook of the project and future developments to extend our knowledge in the actinide landscape.
Experimental studies tailored to unveil fundamental properties of the heaviest actinide elements have recently gained increasing interest and yet the available information remains sparse [1]. Nuclides in this region of the nuclear chart are stabilized by shell effects that retard spontaneous fission and they feature properties distinctly different from those of lighter nuclei. In addition, the atomic structure of these heavy elements features an enhanced impact of relativistic effects affecting their chemical properties compared to the lighter homologes [2]. However, predictions of such atomic and nuclear properties by state-of-the-art theoretical models are challenging and experimental studies are hampered by production capabilities and short half-lives of these nuclides.
Laser spectroscopy has proven itself to be a powerful tool to investigate such characteristics of exotic nuclei widely spread over the nuclear chart [2,3]. Ground-state properties such as the nuclear mean-square charge radius, the nuclear spin and moments, can be extracted by probing known transitions between atomic energy levels. In this context, the development of the RADRIS method, and the first experimental identification of atomic states in nobelium (Z=102), constitute a gateway to laser [4].
Methodological advancements towards new production schemes and an increased sensitivity of the method recently allowed for first on-line laser spectroscopy investigations of fermium (Fm, Z = 100) isotopes. By combining on-line and off-line laser spectroscopy techniques and various production methods, isotope shifts in an atomic transition were determined for eight isotopes ranging from the accelerator-produced 245Fm to the reactor-bred 257Fm. The investigated chain spanning over both sides of the weak deformed shell gap at N = 152 [5] allowed probing its imprint on changes in the mean-square charge radius [6]. The increased sensitivity of this setup additionally yields a decisive benefit for the search of atomic levels in the heaviest actinide element, lawrencium (Z=103) [7], with a tenfold lower production rate as in the nobelium isotone.
New experimental results and methodological advances achieved within the LISA framework will be discussed in view of further perspectives for laser spectroscopy of the heaviest elements. The presented experimental observations give insight into the nuclear structure of the heavy actinides supporting new developments in theoretical models which will eventually improve their predictive power in a key region.
[1] O. Smits et al., Nat Rev Phys 6, 86-98 (2024).
[2] M. Block et al., Prog Part Nucl Phys 116, 103834 (2021).
[3] X. Yang et al., Prog Part Nucl Phys 104005 (2023).
[4] M. Laatiaoui et al., Nature 538, 495–498 (2016).
[5] L. Buskirk et al., Phys Rev C 109, 044311 (2024).
[6] J. Warbinek et al., submitted (2024).
[7] J. Warbinek et al., Atoms 10, 41 (2022).
A ‘hot particle’ is a microscopic fragment deriving from nuclear material. They have been observed in the environment as a result of nuclear accidents such as in Chornobyl and Fukushima, and continue to be a source of contamination. The history of a hot particle is contained in its isotopic composition, characteristic of its origin and interaction with the environment.
Resonant ionization mass spectrometry (RIMS) is a versatile technique that relies on the universality of atomic structure to selectively analyse isotope ratios in a target element. This work demonstrates advances in the SIRIUS RIMS instrument at Leibniz University Hannover for multi-element ultra-trace analysis in nuclear forensics and radioecology.
interactive exhibitions not a guided tour but guides available onsite for questions.