The accurate photoneutron cross section of the^(27)Al nucleus has a significant impact on resolving differences in existing experimental data and enhancing the precision of nuclear reaction rate calculations for^(26)A...The accurate photoneutron cross section of the^(27)Al nucleus has a significant impact on resolving differences in existing experimental data and enhancing the precision of nuclear reaction rate calculations for^(26)Al in nuclear astrophysics.The photoneutron cross sections for the^(27)Al(γ,n)^(26)Al reaction,within the neutron separation energy range of 13.2-21.7 MeV,were meticulously measured using a new flat efficiency detector array at the Shanghai Laser-Electron Gamma Source.The uncertainty of the data was controlled to below 4%throughout the process,and inconsistencies between the present data and existing data from different gamma sources,as well as the TENDL-2021 data,are discussed in detail.These discussions provide a valuable reference for addressing discrepancies in the^(27)Al(γ,n)^(26)Al cross-section data and improving related theoretical calculations.展开更多
The Shanghai Laser Electron Gamma Source(SLEGS)delivers quasi-monochromatic,continuously energy-tunableγ-ray beams.Based on a Photon Activation Analysis(PAA)method,SLEGS built and developed a photon activation analys...The Shanghai Laser Electron Gamma Source(SLEGS)delivers quasi-monochromatic,continuously energy-tunableγ-ray beams.Based on a Photon Activation Analysis(PAA)method,SLEGS built and developed a photon activation analysis platform,including online activation and offiine low background High-Purity Germanium(HPGe)detector measurement systems,as an alternative to direct measurement methods and low-throughput cross-tests.Owing to short half-lives spanning from minutes to days and characteristics such as ease of fabrication,cost-effectiveness,and stability,gold(~(197)Au)and zinc(~(64)Zn)emerge as favorable activation targets for theγ-ray beam flux monitor.Notably,they exhibit a multitude of advantages in monitoring theγ-ray beam flux,typically 10^(5)photons/s,with energies of 13.16 Me V to 19.08 Me V using a 3 mm coarse collimator.In particular,high-fluxγ-ray beam experiments can be conducted effectively.展开更多
The Shanghai Laser Electron Gamma Source(SLEGS, located in BL03SSID) beamline at the Shanghai Synchrotron Radiation Facility(SSRF) is a Laser Compton Scattering(LCS) gamma source used for the investigation of nuclear ...The Shanghai Laser Electron Gamma Source(SLEGS, located in BL03SSID) beamline at the Shanghai Synchrotron Radiation Facility(SSRF) is a Laser Compton Scattering(LCS) gamma source used for the investigation of nuclear structure, which is in extensive demand in fields such as nuclear astrophysics, nuclear cluster structure, polarization physics, and nuclear energy. The beamline is based on the inverse Compton scattering of 10640 nm photons on 3.5 GeV electrons and a gamma source with variable energy by changing the scattering angle from 20° to 160°. γ rays of 0.25-21.1 MeV can be extracted by the scheme consisting of the interaction chamber, coarse collimator, fine collimator, and attenuator. The maximum photon flux for 180° is approximately 10~7 photons/s at the target at 21.7 MeV, with a 3-mm-diameter beam. The beamline was equipped with four types of spectrometers for experiments in( γ,γ'),( γ,n),( γ,p), and( γ,α). At present, Nuclear Resonance Fluorescence(NRF) spectrometry, Flat-Efficiency neutron Detector(FED) spectrometry, neutron Time-Of-Flight(TOF) spectrometry, and Light-Charged Particle(LCP) spectrometry methods have been developed.展开更多
The Shanghai Laser Electron Gamma Source(SLEGS)is a powerful gamma source that provides MeV gamma-ray beams for nuclear science and technology.It was developed as one of the 16 beamline stations in the Phase Ⅱ Projec...The Shanghai Laser Electron Gamma Source(SLEGS)is a powerful gamma source that provides MeV gamma-ray beams for nuclear science and technology.It was developed as one of the 16 beamline stations in the Phase Ⅱ Project of the Shanghai Synchrotron Radiation Facility.The slant-scattering mode is for the first time systematically employed in laser Compton scattering at SLEGS to produce energy-tunable quasi-monoenergetic gamma-ray beams.The SLEGS officially completed its commissioning from July to December 2021.Gamma rays in the energy range of 0.25-21.7 MeV with a flux of 2.1×10^(4)-1.2×10^(7) photons/s and an energy spread of 2-15% were produced during the test.This paper reports the results from commissioning the SLEGS beamline.展开更多
The Shanghai laser electron gamma source(SLEGS)is a powerful tool for exploring photonuclear physics,such as giant dipole resonance(GDR)and pygmy dipole resonance,which are the main mechanisms of collective nuclear mo...The Shanghai laser electron gamma source(SLEGS)is a powerful tool for exploring photonuclear physics,such as giant dipole resonance(GDR)and pygmy dipole resonance,which are the main mechanisms of collective nuclear motion.The goal of the SLEGS neutron time-of-flight(TOF)spectrometer is to measure GDR and specific nuclear structures in the energy region above the neutron threshold.The SLEGS TOF spectrometer was designed to hold 20 sets of EJ301 and LaBr3 detectors.Geant4 was used to simulate the efficiency of each detector and the entire spectrometer,which provides a reference for the selection of detectors and layout of the SLEGS TOF spectrometer.Under the events of 208Pb,implementations of coincidence and time-of-flight technology for complex experiments are available;thus,and neutron decay events can be separated.The performance of SLEGS TOF spectrometer was systematically evaluated using offline experiments,in which the time resolution reached approximately 0.9 ns.展开更多
The Shanghai Laser Electron Gamma Source(SLEGS),built in the Shanghai Synchrotron Radiation Facility,is the first versatile laser Compton slant-scatterin am e in the world.The measurements of 197Au(c,1n)and 159Tb(c,1n...The Shanghai Laser Electron Gamma Source(SLEGS),built in the Shanghai Synchrotron Radiation Facility,is the first versatile laser Compton slant-scatterin am e in the world.The measurements of 197Au(c,1n)and 159Tb(c,1n)reaction cross sections were chosen as the day-one experiment at SLEGS.The SLEGS data are compared with data from the Livermore and Saclay positron annihilation in-flight facilities and with data from the NewSUBARU laser Compton backscattering facility.Our data evidence discrepancies with the results from Livermore and Saclay,while demonstrating consistency with the data from NewSUBARU.This is also consistent with new theoretical predictions.The new measurement lays the foundation for resolving the long-standing discrepancies between the Livermore and Saclay photoneutron cross section data for 19 nuclei in the future.Gamma-ray beams produced at SLEGS await a variety of experiments for nuclear physics,astrophysics and nuclear data as well as for industrial applications.展开更多
This study investigates photonuclear reaction(γ,n)cross-sections using Bayesian neural network(BNN)analysis.After determining the optimal network architecture,which features two hidden layers,each with 50 hidden node...This study investigates photonuclear reaction(γ,n)cross-sections using Bayesian neural network(BNN)analysis.After determining the optimal network architecture,which features two hidden layers,each with 50 hidden nodes,training was conducted for 30,000 iterations to ensure comprehensive data capture.By analyzing the distribution of absolute errors positively correlated with the cross-section for the isotope 159Tb,as well as the relative errors unrelated to the cross-section,we confirmed that the network effectively captured the data features without overfitting.Comparison with the TENDL-2021 Database demonstrated the BNN's reliability in fitting photonuclear cross-sections with lower average errors.The predictions for nuclei with single and double giant dipole resonance peak cross-sections,the accurate determination of the photoneutron reaction threshold in the low-energy region,and the precise description of trends in the high-energy cross-sections further demonstrate the network's generalization ability on the validation set.This can be attributed to the consistency of the training data.By using consistent training sets from different laboratories,Bayesian neural networks can predict nearby unknown cross-sections based on existing laboratory data,thereby estimating the potential differences between other laboratories'existing data and their own measurement results.Experimental measurements of photonuclear reactions on the newly constructed SLEGS beamline will contribute to clarifying the differences in cross-sections within the existing data.展开更多
In recent years,the gap between the supply and demand of medical radioisotopes has increased,necessitating new methods for producing medical radioisotopes.Photonuclear reactions based on gamma sources have unique adva...In recent years,the gap between the supply and demand of medical radioisotopes has increased,necessitating new methods for producing medical radioisotopes.Photonuclear reactions based on gamma sources have unique advantages in terms of producing high specific activity and innovative medical radioisotopes.However,the lack of experimental data on reaction cross sections for photonuclear reactions of medical radioisotopes of interest has severely limited the development and production of photonuclear transmutation medical radioisotopes.In this study,the entire process of the generation,decay,and measurement of medical radioisotopes was simulated using online gamma activation and offline gamma measurements combined with a shielding gamma-ray spectrometer.Based on a quasi-monochromatic gamma beam from the Shanghai Laser Electron Gamma Source(SLEGS),the feasibility of this measurement of production cross section for surveyed medi-cal radioisotopes was simulated,and specific solutions for measuring medical radioisotopes with ultra-low production cross sections were provided.The feasibility of this method for high-precision measurements of the reaction cross section of medical radioisotopes was demonstrated.展开更多
介绍了上海光源线站工程之一的上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)光束线站的建设与试运行情况,在SLEGS装置上可以开展核物理、核天体物理等基础研究、开展伽马辐照、伽马成像及伽马活化等应用研究。SLEG...介绍了上海光源线站工程之一的上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)光束线站的建设与试运行情况,在SLEGS装置上可以开展核物理、核天体物理等基础研究、开展伽马辐照、伽马成像及伽马活化等应用研究。SLEGS光束线站在2021年12月通过工艺验收,2022年10月进入到试运行阶段,2023年9月对用户开放运行。SLEGS是国际上首台采用变换碰撞角度连续改变伽马束能量的光束线站,具有最好的能量扫描精度、流强密度以及高效的能量调节能力。试运行阶段SLEGS光束线站重点解决了伽马束能谱和流强的在线监测问题,主要完成了平坦效率谱仪(FED)测量光中子截面的实验方法学研究,以及开展了伽马成像、伽马活化、正电子产生等应用平台的拓展和研究。随着逆康普顿散射技术的发展和应用需求的增加,未来短脉冲、高极化、高通量以及小型化的激光康普顿散射光源将会迎来更好的发展机遇,将在核物理、天体物理、粒子物理、极化物理,以及航空航天、医学检测、能源开发等伽马源应用研究领域发挥重要的作用。展开更多
基金supported by the National key R&D program(Nos.2023YFA1606901 and 2022YFA1602404)the National Natural Science Foundation of China(Nos.12375123 and 12388102)the Natural Science Foundation of Henan Province(No.242300422048)。
文摘The accurate photoneutron cross section of the^(27)Al nucleus has a significant impact on resolving differences in existing experimental data and enhancing the precision of nuclear reaction rate calculations for^(26)Al in nuclear astrophysics.The photoneutron cross sections for the^(27)Al(γ,n)^(26)Al reaction,within the neutron separation energy range of 13.2-21.7 MeV,were meticulously measured using a new flat efficiency detector array at the Shanghai Laser-Electron Gamma Source.The uncertainty of the data was controlled to below 4%throughout the process,and inconsistencies between the present data and existing data from different gamma sources,as well as the TENDL-2021 data,are discussed in detail.These discussions provide a valuable reference for addressing discrepancies in the^(27)Al(γ,n)^(26)Al cross-section data and improving related theoretical calculations.
基金supported by National Key Research and Development Program of China(Nos.2022YFA1602404 and2023YFA1606901)the National Natural Science Foundation of China(Nos.12275338,12388102,and U2441221)the Key Laboratory of Nuclear Data Foundation(JCKY2022201C152)。
文摘The Shanghai Laser Electron Gamma Source(SLEGS)delivers quasi-monochromatic,continuously energy-tunableγ-ray beams.Based on a Photon Activation Analysis(PAA)method,SLEGS built and developed a photon activation analysis platform,including online activation and offiine low background High-Purity Germanium(HPGe)detector measurement systems,as an alternative to direct measurement methods and low-throughput cross-tests.Owing to short half-lives spanning from minutes to days and characteristics such as ease of fabrication,cost-effectiveness,and stability,gold(~(197)Au)and zinc(~(64)Zn)emerge as favorable activation targets for theγ-ray beam flux monitor.Notably,they exhibit a multitude of advantages in monitoring theγ-ray beam flux,typically 10^(5)photons/s,with energies of 13.16 Me V to 19.08 Me V using a 3 mm coarse collimator.In particular,high-fluxγ-ray beam experiments can be conducted effectively.
文摘The Shanghai Laser Electron Gamma Source(SLEGS, located in BL03SSID) beamline at the Shanghai Synchrotron Radiation Facility(SSRF) is a Laser Compton Scattering(LCS) gamma source used for the investigation of nuclear structure, which is in extensive demand in fields such as nuclear astrophysics, nuclear cluster structure, polarization physics, and nuclear energy. The beamline is based on the inverse Compton scattering of 10640 nm photons on 3.5 GeV electrons and a gamma source with variable energy by changing the scattering angle from 20° to 160°. γ rays of 0.25-21.1 MeV can be extracted by the scheme consisting of the interaction chamber, coarse collimator, fine collimator, and attenuator. The maximum photon flux for 180° is approximately 10~7 photons/s at the target at 21.7 MeV, with a 3-mm-diameter beam. The beamline was equipped with four types of spectrometers for experiments in( γ,γ'),( γ,n),( γ,p), and( γ,α). At present, Nuclear Resonance Fluorescence(NRF) spectrometry, Flat-Efficiency neutron Detector(FED) spectrometry, neutron Time-Of-Flight(TOF) spectrometry, and Light-Charged Particle(LCP) spectrometry methods have been developed.
基金supported by the National Natural Science Foundation of China(Nos.11875311,11905274,12005280)the Chinese Academy of Sciences President’s International Fellowship Initiative(No.2021VMA0025).
文摘The Shanghai Laser Electron Gamma Source(SLEGS)is a powerful gamma source that provides MeV gamma-ray beams for nuclear science and technology.It was developed as one of the 16 beamline stations in the Phase Ⅱ Project of the Shanghai Synchrotron Radiation Facility.The slant-scattering mode is for the first time systematically employed in laser Compton scattering at SLEGS to produce energy-tunable quasi-monoenergetic gamma-ray beams.The SLEGS officially completed its commissioning from July to December 2021.Gamma rays in the energy range of 0.25-21.7 MeV with a flux of 2.1×10^(4)-1.2×10^(7) photons/s and an energy spread of 2-15% were produced during the test.This paper reports the results from commissioning the SLEGS beamline.
基金supported by the National Natural Science Foundation of China (Nos.12275338,12005280,11905274 and 11875311)the Key Laboratory of Nuclear Data foundation (JCKY2022201C152)+1 种基金National key research and development program (No.2022YFA1602404)the Strategic Priority Research Program of the CAS (No.XDB34030000).
文摘The Shanghai laser electron gamma source(SLEGS)is a powerful tool for exploring photonuclear physics,such as giant dipole resonance(GDR)and pygmy dipole resonance,which are the main mechanisms of collective nuclear motion.The goal of the SLEGS neutron time-of-flight(TOF)spectrometer is to measure GDR and specific nuclear structures in the energy region above the neutron threshold.The SLEGS TOF spectrometer was designed to hold 20 sets of EJ301 and LaBr3 detectors.Geant4 was used to simulate the efficiency of each detector and the entire spectrometer,which provides a reference for the selection of detectors and layout of the SLEGS TOF spectrometer.Under the events of 208Pb,implementations of coincidence and time-of-flight technology for complex experiments are available;thus,and neutron decay events can be separated.The performance of SLEGS TOF spectrometer was systematically evaluated using offline experiments,in which the time resolution reached approximately 0.9 ns.
基金supported by the National key R&D program(2022YFA1602400 and 2023YFA1606901)the Science Fund for Creative Research Groups(12388102)+1 种基金the National Natural Science Foundation of China(12147101,12275338,12005280)the Key Laboratory of Nuclear Data Foundation(JCKY2022201C152).
文摘The Shanghai Laser Electron Gamma Source(SLEGS),built in the Shanghai Synchrotron Radiation Facility,is the first versatile laser Compton slant-scatterin am e in the world.The measurements of 197Au(c,1n)and 159Tb(c,1n)reaction cross sections were chosen as the day-one experiment at SLEGS.The SLEGS data are compared with data from the Livermore and Saclay positron annihilation in-flight facilities and with data from the NewSUBARU laser Compton backscattering facility.Our data evidence discrepancies with the results from Livermore and Saclay,while demonstrating consistency with the data from NewSUBARU.This is also consistent with new theoretical predictions.The new measurement lays the foundation for resolving the long-standing discrepancies between the Livermore and Saclay photoneutron cross section data for 19 nuclei in the future.Gamma-ray beams produced at SLEGS await a variety of experiments for nuclear physics,astrophysics and nuclear data as well as for industrial applications.
基金supported by National key research and development program(No.2022YFA1602404)the National Natural Science Foundation of China(Nos.12388102,12275338,12005280)the Key Laboratory of Nuclear Data foundation(No.JCKY2022201C152)。
文摘This study investigates photonuclear reaction(γ,n)cross-sections using Bayesian neural network(BNN)analysis.After determining the optimal network architecture,which features two hidden layers,each with 50 hidden nodes,training was conducted for 30,000 iterations to ensure comprehensive data capture.By analyzing the distribution of absolute errors positively correlated with the cross-section for the isotope 159Tb,as well as the relative errors unrelated to the cross-section,we confirmed that the network effectively captured the data features without overfitting.Comparison with the TENDL-2021 Database demonstrated the BNN's reliability in fitting photonuclear cross-sections with lower average errors.The predictions for nuclei with single and double giant dipole resonance peak cross-sections,the accurate determination of the photoneutron reaction threshold in the low-energy region,and the precise description of trends in the high-energy cross-sections further demonstrate the network's generalization ability on the validation set.This can be attributed to the consistency of the training data.By using consistent training sets from different laboratories,Bayesian neural networks can predict nearby unknown cross-sections based on existing laboratory data,thereby estimating the potential differences between other laboratories'existing data and their own measurement results.Experimental measurements of photonuclear reactions on the newly constructed SLEGS beamline will contribute to clarifying the differences in cross-sections within the existing data.
基金supported by the Strategic Priority Research Program of the CAS(No.XDB34030000)National Natural Science Foundation of China(No.11975210 and No.U1832129)+1 种基金National Key Research and Development Program of China(No.2022YFA1602404)Youth Innovation Promotion Association CAS(No.2017309).
文摘In recent years,the gap between the supply and demand of medical radioisotopes has increased,necessitating new methods for producing medical radioisotopes.Photonuclear reactions based on gamma sources have unique advantages in terms of producing high specific activity and innovative medical radioisotopes.However,the lack of experimental data on reaction cross sections for photonuclear reactions of medical radioisotopes of interest has severely limited the development and production of photonuclear transmutation medical radioisotopes.In this study,the entire process of the generation,decay,and measurement of medical radioisotopes was simulated using online gamma activation and offline gamma measurements combined with a shielding gamma-ray spectrometer.Based on a quasi-monochromatic gamma beam from the Shanghai Laser Electron Gamma Source(SLEGS),the feasibility of this measurement of production cross section for surveyed medi-cal radioisotopes was simulated,and specific solutions for measuring medical radioisotopes with ultra-low production cross sections were provided.The feasibility of this method for high-precision measurements of the reaction cross section of medical radioisotopes was demonstrated.
文摘介绍了上海光源线站工程之一的上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)光束线站的建设与试运行情况,在SLEGS装置上可以开展核物理、核天体物理等基础研究、开展伽马辐照、伽马成像及伽马活化等应用研究。SLEGS光束线站在2021年12月通过工艺验收,2022年10月进入到试运行阶段,2023年9月对用户开放运行。SLEGS是国际上首台采用变换碰撞角度连续改变伽马束能量的光束线站,具有最好的能量扫描精度、流强密度以及高效的能量调节能力。试运行阶段SLEGS光束线站重点解决了伽马束能谱和流强的在线监测问题,主要完成了平坦效率谱仪(FED)测量光中子截面的实验方法学研究,以及开展了伽马成像、伽马活化、正电子产生等应用平台的拓展和研究。随着逆康普顿散射技术的发展和应用需求的增加,未来短脉冲、高极化、高通量以及小型化的激光康普顿散射光源将会迎来更好的发展机遇,将在核物理、天体物理、粒子物理、极化物理,以及航空航天、医学检测、能源开发等伽马源应用研究领域发挥重要的作用。
