The High Energy Photon Source: A 6 GeV and Fourth-Generation Synchrotron Light Source in Beijing

Abstract The high-energy photon source (HEPS) is a 6 GeV, fourth-generation synchrotron light source. As a greenfield light source, the project has spanned more than seven years to complete the design, procurement, assembly, installation, commissioning, and pilot operation. The accelerator complex features a hybrid 7-bend achromat lattice and a 1360 m circumference storage ring. A natural emittance of 55.6 pm·rad has been achieved at a 120 mA beam current with brightness exceeding 1 × 1022 phs/s/mm2/mrad2/0.1% BW. In Phase I, 15 beamlines have been constructed, three of them long beamlines. The first light from an insertion device was delivered downstream to an endstation 350 m away at the ID21 Imaging beamline in October 2024. HEPS had met all of the key performance parameters in October 2025. HEPS is characterized by its high-energy, high-brightness, and high-coherence X-ray capabilities. Following four runs of pilot operations since December 2025, the HEPS formally opens to global users in the second half of 2026.