PIFI-Day on the 23rd SPARC Topical Workshop was held at the Huizhou campus of the Institute of Modern Physics (IMP), Chinese Academy of Sciences (CAS), from September 12 to 15. The workshop was a follow-up meeting to the 22nd International Conference on the Physics of Highly Charged Ions (HCI2026).

The workshop was hosted by IMP and co-organized with the SPARC (Stored Particle Atomic Research Collaboration) of GSI Helmholtzzentrum für Schwerionenforschung and FAIR (Facility for Antiproton and Ion Research), and supported by CAS President's International Fellowship Initiative (PIFI).

Sixty researchers from eight countries and regions, including China, Japan, Greece, Germany, Italy and India, attended the workshop. The event covered topics including atomic collisions with highly charged ions, critical and super-critical fields, laser and X-ray spectroscopy, the cross-link between atomic and nuclear physics, the status of FAIR facilities and instrumentation, the status of the SPARC collaboration, and the status of the High Intensity heavy-ion Accelerator Facility (HIAF) and its first experiments. During the workshop, experts delivered topical presentations on key directions, highlighting the latest research results, frontier theories, cutting-edge experimental techniques and future trends in storage-ring atomic physics worldwide.

Highly charged ions research is a cornerstone of modern atomic physics and high-temperature plasma research. As irreplaceable experimental platforms, storage rings and ion traps make it possible to carry out atomic collision and precision spectroscopy studies with well-defined charge states and energies.

SPARC is one of the collaborations within APPA (Atomic, Biophysics, Plasma physics and Applications), one of the four research pillars of FAIR. The collaboration carries out research on highly charged heavy ions at GSI/FAIR's storage rings and trapping facilities, including the Experimental Storage Ring (ESR), the low-energy storage ring CRYRING, the HITRAP ion trap, and the future High-Energy Storage Ring (HESR).

Supported by major national research infrastructures, China has made significant progress in heavy-ion science and highly charged ion research, with steadily growing international impact. With HIAF entering commissioning operation in July 2026, its experimental terminals, including the high-precision spectrometer ring (SRing), will open up new experimental opportunities for highly charged ion physics and for research at the interface of atomic and nuclear physics.

The success of the workshop further deepened exchanges and cooperation between China and the international academic community in highly charged ion physics and related fields, and laid a foundation for high-level international joint research based on large-scale scientific research facilities such as HIAF and FAIR.

Figure. Group photo of the workshop. (Image from IMP)