辐射研究与辐射工艺学报
2024, 42(1): 010206
1 清华大学 工程物理系北京 100084
2 NRC "Kurchatov Institute" 俄罗斯 莫斯科 123182
加速器驱动次临界系统（Accelerator Driven Sub-critical System，ADS）是最具潜力的下一代核能系统选型之一，准确评估ADS散裂靶内产生的长寿命放射性核素含量是应用研究中的重要课题，利用质子活化法可以有效评价质子与散裂靶材料发生相互作用产生长寿命核素的反应截面。4个质子辐照天然铅样品分别被能量为40 MeV、70 MeV、100 MeV和400 MeV的质子照射90 min、75 min、40 min和25 min，在冷却约20 a后，利用中国锦屏地下实验室（China Jinping Underground Laboratory，CJPL）的超低本底γ谱仪GeTHU进行测量，使用SAGE（Simulation and Analysis for Germanium Experiments）模拟框架计算了GeTHU的探测效率，测定了能量为40 MeV、70 MeV、100 MeV和400 MeV质子与天然铅发生natPb（p，x）207Bi和natPb（p，x）194Hg反应的总产生截面，并与其他理论及实验工作的结果进行了比较，基于相同样品的实验测量结果在误差范围内保持一致，natPb（p，x）207Bi的反应截面与TENDL的评价截面更为接近，natPb（p，x）194Hg的截面结果与INCL++/ABLA的理论预期保持一致，这些截面结果为ADS设施的放射性废物评估提供了实验依据。
GeTHU 激发函数 铅靶 剩余核素 CJPL GeTHU Excitation function Pb-target Residual nuclides CJPL 
Author Affiliations
Abstract
1 Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
3 Department of Engineering Physics, Tsinghua University, Beijing 100084, China
We propose a new injection scheme that can generate electron beams with simultaneously a few permille energy spread, submillimeter milliradian emittance, and more than a 100 pC charge in laser wakefield accelerators. In this scheme, a relatively loosely focused laser pulse drives the plasma wakefield, and a tightly focused laser pulse with similar intensity triggers an interference ring pattern that creates onion-like multisheaths in the plasma wakefield. Owing to the change in wavefront curvature after the focal position of the tightly focused laser, the innermost sheath of the wakefield expands, which slows down the effective phase velocity of the wakefield and triggers injection of plasma electrons. Both quasicylindrical and fully three-dimensional particle-in-cell simulations confirm the generation of beams with the above mentioned properties.
Matter and Radiation at Extremes
2022, 7(5): 054001
强激光与粒子束
2022, 34(4): 049002
Author Affiliations
Abstract
1 Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, Institute of Modern Optics, Nankai University, Tianjin 300350, China
2 School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072, China
We demonstrate that the directionality of far-field second harmonic (SH) emission generated from individual gold nanosphere can be flexibly engineered by manipulating three-dimensional (3D) focal polarization orientation of the excitation field, which is explained by the coherent interference between SH dipolar and quadrupolar emission modes. The SH dipolar emission mode is independent of the polarization direction of the fundamental field whereas the evolution of the focal polarization orientation can dramatically modify the quadrupolar emission pattern. Therefore, the resultant SH emission pattern has a polarization-dependent behavior and side scattering almost perpendicular to the propagation direction of the incident light can be observed under a specific condition. Our findings provide a novel degree of freedom for all-optical control of directional nonlinear scattering from single nanoantenna, thereby opening new possibilities for future potential applications.
光电子快报（英文版）
2021, 17(2): 65
Author Affiliations
Abstract
1 Institute of Modern Optics, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, Nankai University, Tianjin 300350, China
2 School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072, China
Broadband transverse displacement sensing by exploiting the interaction of a focused radially polarized beam with a silicon hollow nanodisk is proposed. The multipolar decomposition analysis indicates that the interference between a longitudinal total electric dipole (TED) moment and a lateral magnetic dipole (MD) moment is dominant in the far-field transverse scattering in the near-infrared region. Within a broadband wavelength range with the width of 155 nm, the longitudinal TED is almost in phase with the lateral MD, and then broadband position sensing based on the sensitivity of scattering directivity to transverse displacement can be achieved.
directional scattering transverse Kerker’s condition displacement sensing hollow nanodisk radial polarization Chinese Optics Letters
2020, 18(6): 063602
郑逸凡 1,2,3,4,*曾志 1,2,3曾鸣 1,2,3王学武 1,2,3赵自然 1,2,3
1 国家工程实验室, 北京 100084
2 粒子技术与辐射成像教育部重点实验室（清华大学）, 北京 100084
3 清华大学 工程物理系, 北京 100084
4 瑞典皇家理工学院 物理系, 斯德哥尔摩 106 91
在集装箱安检中一个很重要的亟待解决的问题是如何有效地检测出藏在金属中的毒品和爆炸物。传统的X射线CT难以穿透较厚的金属材料，而中子CT引入了很大的放射性，其屏蔽问题是一个难点。相较之下，宇宙线缪子成像是一种有前景的非破坏性成像技术，因为缪子来源于天然的宇宙射线且有足够的能量完全穿透大型集装箱。本文研究了在可接受的测量时间内，宇宙线缪子成像方法能够在何种程度上识别毒品爆炸物与空气和金属。基于清华大学缪子实验平台TUMUTY并通过Geant4模拟宇宙线缪子与物质的相互作用，毒品爆炸物及不同金属材料的散射密度能够被重建出来。基于模式识别的SVM分类器被训练出来对这些材料进行自动识别分类。结果显示，对于边长为20 cm的不同材料的物块，在10到30 min的测量时间内，能够通过缪子成像方法识别毒品爆炸物与金属材料和本底，分类的错误率约为1%；测量时间为1 min时，分类的错误率恶化为12.9%。
缪子成像 散射密度 毒品与爆炸物 模式识别 muon tomography scattering density drugs and explosives machine learning 强激光与粒子束
2018, 30(8): 086002
Author Affiliations
Abstract
Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240, China
Ionization-induced electron injection in laser wakefield accelerators, which was recently proposed to lower the laser intensity threshold for electron trapping into the wake wave, has the drawback of generating electron beams with large and continuous energy spreads, severely limiting their future applications. Complex target designs based on separating the electron trapping and acceleration stages were proposed as the only way for getting small energy-spread electron beams. Here, based on the self-truncated ionization-injection concept which requires the use of unmatched laser–plasma parameters and by using tens of TW laser pulses focused onto a gas jet of helium mixed with low concentrations of nitrogen, we demonstrate single-stage laser wakefield acceleration of multi-hundred MeV electron bunches with energy spreads of a few percent. The experimental results are verified by PIC simulations.
ionization injection ionization injection laser–plasma acceleration laser–plasma acceleration PIC simulations PIC simulations self-truncation self-truncation wakefield wakefield High Power Laser Science and Engineering
2016, 4(3): 03000e24
1 清华大学 工程物理系, 粒子技术与辐射成像教育部重点实验室， 北京 100084
2 西北核技术研究所， 西安 710024
3 华北电力大学 核科学与工程学院， 北京 102206
提出使用面源进行效率转移法刻度133Xe气体体源的探测效率。使用133Ba面源模拟刻度放射性133Xe气体体源的探测效率，在刻度的过程中利用137Cs与133Ba的峰效率比值及133Ba面源远端无符合相加效应，137Cs能峰远近都无符合相加效应等，结合软件模拟建立远近距离峰效率比值的关系，来解决133Ba的符合相加效应。最后，使用面源效率转移法进行气体体源效率刻度，转移法刻度结果和面源模拟法刻度计算值的偏差在±1％以内。
面源 效率刻度 disk source LabSOCS LabSOCS efficiency calibration 强激光与粒子束
2014, 26(9): 094005
1 南京航空航天大学 机电学院, 南京 210016
2 上海航天控制技术研究所, 上海 200233
为了满足自适应光学系统实时快速的工作要求, 将自动控制理论引入到自适应光学系统中, 在不改变系统硬件性能的基础上对系统的控制部分进行了研究。首先, 对自适应光学闭环控制系统进行分析, 将其模块化并建立相应的数学模型;其次, 在自动控制理论基础上设计控制器和相应的控制算法, 并分析了控制器的性能;最后, 将自动控制理论的控制方法与人眼波前像差校正相结合, 使控制算法应用到自适应光学系统波前像差的校正中。结果表明, 相对于传统的自适应光学系统控制方法(纯积分控制和比例-积分控制), Smith预补偿控制使自适应光学控制系统具有较高的闭环带宽和较好的动态、稳态控制性能;在模拟人眼波前像差迭代校正过程中, Smith预补偿控制器校正残余像差的快速性最好;在实际人眼动态像差校正中, Smith预补偿控制校正的残余像差值达到最小,有利于自适应光学控制系统优化。
集成光学 自适应光学 纯积分控制 比例-积分控制 Smith预补偿控制 波前校正 integrated optics adaptive optics integrator control proportion-integration control Smith estimating precompensation control wave-front aberration correction
