Speaker
Description
The SPIRAL2 facility is a new research infrastructure in GANIL powered by its superconducting linear accelerator of light and heavy ions which is currently in operation. The Super Separator Spectrometer (S$^3$) is one of the research facilities aimed at producing exotic nuclei by fusion-evaporation reactions with the accelerated heavy-ion beams, enabling their separation from the primary beam and their delivery to a focal-plane experimental installation [1]. The S$^3$Low Energy Branch (S$^3$-LEB) is the first focal-plane experiment which will use beams from S$^3$, wto stop the fusion-evaporation products in a gas-filled catcher and study their nuclear properties at very low energy.
The key feature of the S$^3$-LEB experiment is the implementation of the in-gas laser ionization and spectroscopy (IGLIS) technique [2], which means that the radioactive nuclei entering the gas catcher from S$^3$ will be neutralized, extracted to a vacuum chamber by a supersonic gas jet, to be then selectively re-ionized in the jet by wavelength-tunable lasers. The photo-ions will be delivered to a series of setups which will either determine their mass, measure their decay radiation, or perform ion counting. The latter mode can be combined with scans of the wavelength of one of the lasers acting in the jet to perform very sensitive measurements of laser spectroscopy. Together, all the techniques available at S$^3$-LEB will allow determining a wide range of low-energy nuclear properties, including the binding energies, mean-square charge radii and static electromagnetic moments, as well as half-lives and decay schemes.
The S$^3$-LEB setup has been commissioned off line with stable isotopes [3, 4] and is now installed at the focal plane of S$^3$, in preparation for on-line commissioning. This contribution will present the fundamentals of the IGLIS technique and its implementation at S$^3$-LEB, as well as results of laser spectroscopy and mass spectrometry from the off-line commissioning of the setup. Ongoing developments and perspectives for experiments with radioactive ion beams will also be discussed.
[1] F. Déchery et al., Nucl. Instrum. Meth. B 376, 125-130 (2016)
[2] R. Ferrer et al., Nat. Comm. 8, 14520 (2017)
[3] J. Romans, et al., Nucl. Instrum. Meth. B 536, 72 (2023)
[4] A. Ajayakumar, et al., NIM B 539, 102 (2023)
