Laser Resonance Chromatography at S3: a Method for Superheavy Element Spectroscopy

by Tudor Stefan (1^st year PhD student)

Atomic spectra serve as unique fingerprints for the elements and provide the most precise means to study their electronic structure, as well as reveal properties of atomic nuclei through hyperfine spectroscopy. Spectroscopic characterization has been advancing towards ever heavier atomic species, with superheavy elements (SHE) being of particular interest due to their role in understanding nuclear stability at the top of the nuclear chart. Currently, spectroscopic characterization has reached as far as nobelium (Z = 102), which has been studied via resonance ionization spectroscopy [1, 2]. The spectra of heavier elements have remained elusive, primarily due to the short half-lives of the radionuclides combined with low production rates in nuclear fusion-evaporation reactions, requiring faster measurements and higher experimental sensitivities.

A potential solution to overcome these obstacles is the newly conceived technique of laser resonance chromatography (LRC) [3], which combines laser probing with ion mobility spectrometry. The change in an ion’s drift time towards a particle detector for different electronic states can reveal the resonant laser excitation from the ground to an excited state. This method circumvents the need for resonance ionization and fluorescencedetection, allowing for a fast and sensitive study of elements such as lawrencium (Z=103), as well as some SHEs of extremely reduced production rates.

In this seminar I will present the LRC technique, focusing on the development of its alpha-decay detection system. In particular, I will discuss the SIMION simulation efforts dedicated to the design of the steering and detection section of the LRC experiment, as well as present the experimental design to be implemented at the S3 installation of GANIL/SPIRAL2 for the spectroscopic characterization of neutron-deficient actinium (Z = 89) and lawrencium (Z = 103) isotopes.

References:
[1] M. Laatiaoui et al., Nature 538 (2016) 495.
[2] J. Lantis et al., Phys. Rev. Res. 6 (2024) 023318
[3] M. Laatiaoui et al., PRL 125 (2020) 023002.