分类: 物理学 >> 核物理学 提交时间: 2024-04-28
摘要: 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), and (γ,p 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.
分类: 物理学 >> 核物理学 提交时间: 2024-02-16
摘要: The Shanghai Laser Electron Gamma Source(SLEGS) has delivered a quasi-monochromatic, continuously energy-tunable gamma-ray beam. Based on the photon activation analysis(PAA) method, SLEGS has built and developed a photon activation analysis platform, including online activation and offline low-background HPGe detector measurement systems, as an alternative to direct measurement methods and a cross-tests at low throughput. Due to the short half-lives spanning from minutes to days and characteristics such as ease of fabrication, cost-effectiveness, and stability, gold (197Au) and zinc (64Zn) emerge as favorable activation targets in the gamma-ray beam flux monitor. Notably, their utility shows a multitude of advantages in monitoring the gamma-ray beam flux typically 105 photons/s with the energy of 13.16 to 19.08 MeV under the condition of the 3 mm coarse collimator. Especially in high-flux $\gamma$-ray beam experiments can be well applied.
分类: 物理学 >> 核物理学 提交时间: 2024-02-28
摘要: 上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)是通过激光与电子逆康普顿散射产生准单能、能量连续可调的兆电子伏伽马束,是目前国际上唯一一台可连续变换碰撞角度的激光康普顿散射(Laser Compton Scattering,LCS)伽马源装置。伽马活化是研究材料特性的有效手段之一,本文介绍了上海激光电子伽马源的伽马活化平台情况、包括在线活化过程,离线低本底测量,高纯锗(High Purity Germanium,HPGe)探测器的能量效率刻度等。目前的简易低本底屏蔽使得测量系统本底计数率降低到约 5.2cps/(60 keV-3 MeV 能区)。SLEGS 伽马源的活化平台为开展伽马活化测量研究提供了有利条件,未来在核物理、核天体物理、医学应用、材料科学和环境科学等领域的研究将会发挥重要的作用。
分类: 物理学 >> 核物理学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2023-06-20
摘要: 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-fight (TOF) spectrometer is to measure GDR and specifc 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 efciency 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-fight technology for complex experiments are available; thus, y and neutron decay events can be separated. The performance of SLEGS TOF spectrometer was systematically evaluated using ofine experiments, in which the time resolution reached approximately 0.9ns.