Key Milestones of High Energy Photon Source (HEPS): all key performance parameters of HEPS accelerator achieved

The High Energy Photon Source (HEPS), the first fourth-generation synchrotron light source in Asia, passed on-site key performance tests of the HEPS accelerator in Beijing from September 26 to 29, 2025. All Key Performance Parameters (KPPs) of HEPS accelerator met or exceeded the acceptance criteria. The test result are as follows: storage-ring beam energy of 6.01 GeV; emittance of 0.0568 nm · rad; beam current of 100.5 mA; vertical orbit stability better than 19.8% of the vertical beam size; and brightness of 4.00 × 10 21 phs / ( s · mm 2 · mrad 2 · 0.1 % BW ) . The X-ray photon-energy reached 349.57 keV, demonstrating the capability to deliver 300 keV X-rays. These achievements result from more than six years of sustained effort in construction and overcoming key technical challenges, and the recent iterative beam commissioning from July 23, 2024 to optimize accelerator performance. The achievement of the HEPS accelerator KPPs placed HEPS at the international forefront of synchrotron light sources and provide a solid foundation for stable beam delivery to beamlines and for cutting-edge scientific research.