Time-resolved ultra-small-angle X-ray scattering beamline (BL10U1) at SSRF

The construction of a new beamline, BL10U1, was completed at the Shanghai synchrotron radiation facility in 2020. This multipurpose beamline was designed to provide X-ray scattering techniques such as ultra-small-angle X-ray scattering (USAXS), small-angle X-ray scattering (SAXS), wide-angle X-ray scattering, and microfocus SAXS (μSAXS) for a broad user community. To realize fast time-resolved USAXS experiments, the beamline adopted an in-vacuum undulator with a total length of 1.6 m as the photon source. An in-house cryogenic-cooled double multilayer monochromator was installed to deliver a photon flux of approximately 10¹³ photons/s at a photon energy of 10 keV. The three-year successful operation of this beamline demonstrated that the monochromator operated smoothly, as expected. BL10U1 has three end stations in succession: USAXS end station, μSAXS end station, and end station for industrial applications. The minimum scattering vector q ~ 0.0042 nm⁻¹ at 10 keV can be achieved at the USAXS end station equipped with a 28 m-long and 1.8 m-diameter vacuum flight tube. At the μSAXS end station, a beam spot of less than 10 × 8 μm was achieved for micro-SAXS experiments. In contrast, in situ experimental instruments up to 5 m high and 8 m wide can be mounted at the industrial application end station, which offers industrial scientists the opportunity to use their large industrial equipment. BL10U1 opens up a new capability to investigate phenomena such as non-equilibrium and dynamic processes of materials with a wide length scale from angstroms to micrometers with millisecond time resolution. In this paper, we also report beamline design considerations and commissioning results.