Speaker
Description
Radioactive molecules have recently emerged as precision probes for anomalous electromagnetic moments, possibly offering unprecedented sensitivity to parity violation and time reversal symmetry violation [1]. In current experiments at radioactive ion beam facilities, the high temperature of the different molecular degrees of freedom is a crucial limiting factor for sensitive measurements. To reach the required temperatures of a few millikelvins, several cooling techniques are available; however, the gap to bridge from ambient temperature to a few millikelvin is too large.
This challenge can be directly addressed at the SPIRAL2-S3 facility in GANIL. At the Super Separator Spectrometer (S3) focal point, the S3 Low Energy Branch (S3-LEB) is a setup dedicated to the study of radionuclides using laser spectroscopy, decay spectroscopy and mass spectrometry [2]. The key aspect of S3-LEB is the application of the in-gas-jet laser ionization spectroscopy technique [3], which would allow to produce cold molecules within a long and collimated supersonic gas jet, at temperatures of T_trans ~ 13 K [4].
Recently, a R&D offline setup for S3-LEB, called FRIENDS3 (Fast Radioactive Ion Extraction and Neutralization Device for S3), has been conceived, assembled and is currently in its test phase at GANIL [5,6]. The FRIENDS3 setup provides an opportunity for offline development focused on controlled production of cold molecules. Our objectives in this current phase are the implementation of a gas purification system, an efficient ion neutralization mechanism, and stable, long-range laser scans for probing the produced molecules.
In this contribution, the efforts made towards laser spectroscopy of molecules at S3-LEB will be presented. I will contextualize these efforts in the framework of our long-term goals and show the current status of FRIENDS3, which include its recent developments and the required laser setup, as well as our future steps.
[1] G. Arrowsmith-Kron et al., Rep. Prog. Phys. 87 (2024)
[2] A. Ajayakumar et al. Nucl.Instrum.Meth.B 539 102 (2023)
[3] R. Ferrer. et.al., Nat. Commun. 8, 14520 (2017)
[4] W. Dong, PhD thesis, Université Paris-Saclay (2024)
[5] W. Dong et al., arXiv:2601.12009 [physics] (2026)
[6] E. Morin et al., NIM B, 166027 (2026)