Overview of SSRF phase-Ⅱ beamlines

The SSRF phase-Ⅱ beamline project was launched in 2016. Its major goal was to establish a systematic state-of-the-art experimental facility for third-generation synchrotron radiation to solve problems in cutting-edge science and technology.Currently, the construction is fully completed. All 16 newly built beamlines with nearly 60 experimental methods passed acceptance testing by the Chinese Academy of Sciences and are in operation.

The MING proposal at SHINE:megahertz cavity enhanced X‑ray generation

The cavity-based X-ray free-electron laser(XFEL)has promise in producing fully coherent pulses with a bandwidth of a few meV and very stable intensity,whereas the currently existing self-amplified spontaneous emission(SASE)XFEL is capable of generating ultra-short pulses with chaotic spectra.In general,a cavity-based XFEL can provide a spectral brightness three orders of magnitude higher than that of the SASE mode,thereby opening a new door for cutting-edge scientific research.With the development of superconducting MHz repetition-rate XFEL facilities such as FLASH,European-XFEL,LCLS-II,and SHINE,practical cavity-based XFEL operations are becoming increasingly achievable.In this study,megahertz cavity enhanced X-ray generation(MING)is proposed based on China’s first hard XFEL facility-SHINE,which we refer to as MING@SHINE.

Static superconducting gantry‑based proton CT combined with X‑ray CT as prior image for FLASH proton therapy

Proton FLASH therapy with an ultra-high dose rate is in urgent need of more accurate treatment plan system(TPS)to promote the development of proton computed tomography(CT)without intrinsic error compared with the transformation from X-ray CT.This paper presents an imaging mode of proton CT based on static superconducting gantry different from the conventional rotational gantry.The beam energy for proton CT is fixed at 350 MeV,which is boosted by a compact proton linac from 230 MeV,and then delivered by the gantry to scan the patient’s body for proton imaging.This study demonstrates that the static superconducting gantry-based proton CT is effective in clinical applications.In particular,the imaging mode,which combines the relative stopping power(RSP)map from X-ray CT as prior knowledge,can produce much a higher accuracy RSP map for TPSs and positioning and achieve ultra-fast image for real-time image-guided radiotherapy.This paper presents the conceptual design of a boosting linac,static superconducting gantry and proton CT imaging equipment.The feasibility of energy enhancement is verified by simulation,and results from Geant4 simulations and reconstruction algorithms are presented,including the simulation verification of the advantage of the imaging mode.

Design,fabrication,and cold-test results of C-band spherical RF pulse compressor prototype

Purpose Pulse compressor is a useful and common RF structure for Free Electron Laser and Linear Collider Facilities, whichcan improve the input power of accelerating structures significantly.Methods In this study, we designed, fabricated and tested a prototype of a compact C-band spherical pulse compressor.This pulse compressor utilizes one high Q0 spherical RF resonant cavity that works with two degenerated TE1,1,3modes anda dual-mode polarized coupler. The cavity and coupler were designed and machined separately and then brazed together.The prototype was tested carefully using vector network analyzer, and a cold-test system was set up to check the workingconditions of the spherical pulse compressor with inversed input powerResults Associated with the C-band high-gradient accelerating structures, the peak power gain and energy multiply factorcan be as high as 6.1 and 1.85, respectively, in theory. The average power gain is 3.8 in the first 0.372 μs after the phasereverse, which is the accelerator filling time. During the cold test, a peak power multiply factor of 6.04 and an energy multiplyfactor of 1.83 were achieved.Conclusions The test results agreed with the design well. The prototype was successfully made as a pre-research for thefuture energy multiplying scheme of SXFEL.