Article title: Commissioning of laser electron gamma beamline SLEGS at SSRF

上海光源（SSRF）激光电子伽玛束线SLEGS的调试

DOI:10.1007/S41365-022-01076-0

一句话概要：

The laser electron gamma beamline SLEGS at SSRF has been commissioned successfully.

上海光源（SSRF）的激光电子伽玛束线SLEGS调试成功。

http://www.nst.sinap.ac.cn/newsDetails/112/29403/en/

The Novelty (What)

创新性（主要内容）

The state-of-the-art Shanghai Laser Electron Gamma Source (SLEGS) has officially completed its commissioning which lasted from July to December 2021. Other than a back-scattering mode, for the first time, a slant-scattering mode is adopted in the SLEGS beamline to generate powerful quasi-monoenergetic gamma-ray beams systematically. With an energy spread of 2 – 15 %, a gamma-ray beam with energy ranging from 0.25 to 21.1 MeV in slant-scattering at collision angles ranging from 20 – 160° is generated. In back-scattering at 180°, the beam achieves maximum energy of 21.7 MeV. Notably, a 2 % energy resolution can achieved with a 1-mm or smaller collimator. The SLEGS beamline primarily comprises four components: i) a 100-W CO₂ laser and laser transport; ii) an interaction chamber (slant-scattering) and a multi-function chamber (back-scattering); iii) two-stage coarse and fine collimators and a gamma flux attenuator; and iv) an experimental hutch, an experimental detector, a gamma absorber, and a data acquisition system. In order to establish a more in-depth understanding of the energy resolution, more realistic Geant4 simulations can be deployed to carry out a thorough analysis in the future.

最先进的上海激光电子伽玛源(SLEGS)正式完成了从2021年7月到12月的调试。 在SLEGS光束线上首次采用了斜散射模式，而不只是背散射模式，系统地产生了强的准单能伽玛射线束。 在20～160°碰撞角范围内，产生了能量为0.25～21.1MeV的斜散射γ射线束，能量扩展为2～15%。 在180°背散射时，光束的最大能量为21.7MeV。 值得注意的是，用1毫米或更小的准直器可以获得2%的能量分辨率。 SLEGS光束线主要由四部分组成:I)100W CO₂激光器和激光传输； ii）相互作用室（斜散射）和多功能室（背散射）； iii）粗准直器和细准直器两级准直以及伽玛通量衰减器； 实验棚屋、实验探测器、γ吸收器和数据获取系统。 为了对能量分辨率建立更深入的理解，未来可以部署更精确的Geant4模拟来进行详尽的分析。

The Background (Why)

研究背景（主要原因）

The laser Compton scattering (LCS) gamma source is currently the most advanced quasi-monoenergetic gamma-ray source supporting photonuclear physics research. Meanwhile, slant-scattering is an essential technology to produce gamma-ray beams with tunable energy at synchrotron radiation facilities which operate at fixed electron beam energy. Hence, in an attempt to establish a world-class high-energy laser electron gamma source, scientists in China have recently commissioned the Shanghai Laser Electron Gamma Source (SLEGS) which adopt both slant- and back-scattering mode to yield MeV gamma-ray beams. By doing so, a new milestone has been achieved by the Shanghai Synchrotron Radiation Facility (SSRF) for having a total of 16 beamline stations in its Phase II Project. With the readiness of SLEGS in facilitating both basic and applied research in nuclear physics, scientists will have more space and opportunity to contribute to the advance of the nation’s nuclear technology.

激光康普顿散射(LCS)伽玛射线源是目前支持光核物理研究的最先进的准单能伽玛射线源。 同时，斜散射是在固定电子束能量的同步辐射装置上产生能量可调谐伽玛射线束的一项重要技术。 为此，最近中国科学家建成了上海激光电子伽玛源(SLEGS)，该源采用斜散射和背散射两种模式产生MeV能量的伽玛射线束，建立了世界一流的高能量激光电子伽玛源。 SLEGS束线站的建成使得上海光源(SSRF)二期工程（共有16条束线站）也达到了一个新的能量范围里程碑。 随着SLEGS线站准备就绪，在促进核物理基础和应用研究方面，科学家将有更多的空间和机会为国家核技术的进步做出贡献。

The SDG impact (Big Why)

SDG影响力（研究意义）

To-date, the number of facilities with high-energy laser electron gamma sources dedicated to nuclear science studies remains scanty globally. Since SLEGS is a high-potential multi-functional experimental platform, the addition of SLEGS to the Shanghai Synchrotron Radiation Facility will be of significant impact to the expansion of nuclear research, especially in China. By supporting the advancement of nuclear technology, this study shows good alignment with United Nations Sustainable Development Group (UNSDG)  9: Industry, innovation & infrastructure.

迄今为止，在全球范围内，用于核科学研究的高能量激光电子伽玛源设施数量仍然很少。 SLEGS是一个高潜力、多功能的实验平台，上海光源中SLEGS线站的加入将对核科学研究的发展，特别是中国核科学研究的发展产生重大影响。 通过支持核技术的进步，这项研究与联合国可持续发展目标9：产业、创新和基础设施保持一致。

研究课题组：

激光伽马组由原中国科学院上海应用研究所（SINAP）核物理室的部分职工、新进人员及在学研究生组成，成立于2020年12月，研究组主要负责上海光源（SSRF）的激光电子伽马源（SLEGS）光束线站的物理设计、工程建设及运行维护，以及开展光核物理的基础和应用研究，此外还承担上海光源的HPGe探测器的研发任务。研究组目前有2位科学顾问，4+1位职工，5位研究生。