Title: Collinear Laser Spectroscopy of $^{21–24}$Na isotopes at the RAON CLaSsy Beamline
Speaker: Junho Won (CENS, Institute for Basic Science, Korea) on behalf of the CLaSsy Collaboration
Abstract: Collinear laser spectroscopy provides a sensitive probe of hyperfine interactions, electromagnetic moments, and isotope shifts in short-lived nuclei. In particular, radioactive sodium isotopes near the N = Z line provide a useful testing ground for both nuclear-structure studies and precision atomic calculations.
In this seminar, I will present recent progress of the CLaSsy collinear laser spectroscopy beamline at the RAON ISOL facility in Korea, with a focus on the first online spectroscopy campaign on neutron-deficient sodium isotopes. Radioactive sodium beams were produced from a SiC target bombarded by a 70-MeV proton beam, mass separated, accelerated to 20 keV, cooled and bunched in an RFQ cooler-buncher, and delivered to the CLaSsy beamline. After charge exchange, neutral sodium atoms were probed on the atomic D1 transition using a 589-nm laser, and fluorescence photons were detected in time coincidence with the ion bunches.
The talk will discuss the experimental method, including the use of collinear and anti-collinear geometries to control beam-energy-related systematics. I will present the hyperfine-structure analysis of 21Na, focusing on the extraction of the magnetic-dipole hyperfine constants A(3s$^2$S$^{1/2}$) and A(3p$^2$P$^{1/2}$). The results are compared with previous measurements and with relativistic coupled-cluster calculations, providing a benchmark for higher-order electron-correlation effects. I will also summarize recent upgrades of the CLaSsy setup and discuss the outlook for future isotope-shift and charge-radius measurements of sodium isotopes at RAON.
