分类： 核科学技术 >> 核科学与技术 提交时间： 2024-05-11
摘要： The Dynamics beamline (D-Line), which combines synchrotron radiation infrared spectroscopy (SR-IR) and energy-dispersive X-ray absorption spectroscopy (ED-XAS), is the first beamline in the world to realize concurrent ED-XAS and SR-IR measurements at the same sample position on a millisecond time-resolved scale. This combined technique is effective for investigating rapid structural changes in atoms, electrons, and molecules in complicated disorder systems, such as those used in physics, chemistry, materials science, and extreme conditions. Moreover, ED-XAS and SR-IR can be used independently in the two branches of the D-Line. The ED-XAS branch is the first ED-XAS beamline in China, which uses a tapered undulator light source and can achieve approximately 2.5 × 1012 photons/s•300 eV BW@7.2 keV at the sample position. An exchangeable polychromator operating in the Bragg-reflection or Laue-transmission configuration is used in different energy ranges to satisfy the requirements for beam size and energy resolution. The focused beam size is approximately 3.5 μm (H) × 21.5 μm (V), and the X-ray energy range is 5–25 keV. Using one- and two-dimensional position-sensitive detectors with frame rates of up to 400 kHz enables time resolutions of tens of microseconds to be realized. Several distinctive techniques, such as the concurrent measurement of in-situ ED-XAS and infrared spectroscopy, time-resolved ED-XAS, high-pressure ED-XAS, XMCD, and pump–probe ED-XAS, can be applied to achieve different scientific goals.
分类： 物理学 >> 核物理学 提交时间： 2024-02-28
Yang yuxuan
Zhang Yue
Zhao Weijuan
Wang Hongwei
Fan Gongtao
Xu Hanghua
Liu Longxiang
Hao Zirui
Li Zhicai
Jin Sheng
Chen Kaijie
Jiao Pu
Zhou Mengdie
Wang Zhenwei
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 提交时间： 2023-12-28
摘要： Radio frequency quadrupoles (RFQs), which are crucial components of proton injectors, significantly affect the performance of proton accelerator facilities. An RFQ with a high frequency of 714 MHz dedicated to compact proton injectors for medical applications is designed in this study. The RFQ is designed to accelerate proton beams from 50 keV to 4 MeV within a short length of 2 m and can be matched closely with the downstream drift tube linac to capture more particles through a preliminary optimization. To develop an advanced RFQ, challenging techniques, including fabrication and tuning method, must be evaluated and verified using a prototype. An aluminium prototype is derived from the conceptual design of the RFQ and then redesigned to confirm the radio frequency performance, fabrication procedure, and feasibility of the tuning algorithm. Eventually, a new tuning algorithm based on the response matrix and least-squares method is developed, which yields favorable results based on the prototype, i.e., the errors of the dipole and quadrupole components reduced to a low level after several tuning iterations. Benefiting from the conceptual design and techniques obtained from the prototype, the formal mechanical design of the 2-m RFQ is ready for the next manufacturing step.
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