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1.
中子在探测器中能产生与暗物质粒子(WIMPs)类似的核反冲信号,对于低背景的暗物质直接探测实验,精确测量和排除中子的干扰尤其重要。为测量中国锦屏地下实验室(CJPL)中子本底的通量,研制了高效的、具有很强"中子-伽马"分辨的掺钆液闪快中子探测器。介绍了掺钆液闪中子探测器的研制和性能,包括探测器形状和尺寸的设计,液体闪烁体类型、光电倍增管型号以及液闪容器材料的选择,探测器的伽马能量刻度以及中子与伽马信号的甄别。用Am-Be中子源对探测器进行探测效率刻度,得到阈值为0.2 MeV等效电子能量的中子探测效率为(6.30±0.30)%,满足中国锦屏地下实验室对中子通量测量的要求。  相似文献   
2.
以空间刚架结构为研究对象,应用谱元法研究其动力学特性,依次推导出杆、轴和铁木辛柯梁的动力学刚度阵,进而得到空间刚架的动力学刚度阵和频域响应的理论方程,拓展了谱元法应用范围。编程计算获得空间刚架的固有频率和点的谐响应曲线,与有限元分析相比较,进一步得到载荷下的瞬态响应。研究表明,谱元法在刚架结构的动力学特性分析中,比有限元方法高效高精度,更适宜解决中高频振动问题。  相似文献   
3.
陈学前  冯加权  杜强 《力学与实践》2006,28(5):47-49,53
利用ANSYS的APDL(ANSYS Parametric Design Language)语言的强大功能,结合工程实际问题,实现了随机振动试验数值仿真计算中基础输入功率谱的自动反馈识别.反馈过程中使用多个表格来存储基础输入谱,突破了基础输入谱只能用50个以内的数据点来描述的限制,故可以一次性完成基础输入谱的反馈识别,大大提高计算效率与精度.  相似文献   
4.
Thomson scattering X-ray sources are compact and affordable facilities that produce short duration, high brightness X-ray pulses enabling new experimental capacities in ultra-fast science studies, and also medical and industrial applications. Such a facility has been built at the Accelerator Laboratory of Tsinghua University, and upgrade is in progress. In this paper, we present a proposed layout of the upgrade with design parameters by simulation, aiming at high X-ray pulses flux and brightness, and also enabling advanced dynamics studies and applications of the electron beam. Design and construction status of main subsystems are also presented.  相似文献   
5.
A TW (Tera Watt) laser system based on Ti:sapphire mainly for the Tsinghua Thomson scattering X-ray light source (TTX) is being built. Both UV (ultraviolet) laser pulse for driving the photocathode radiofrequency (RF) gun and the IR (infrared) laser pulse as the electron-beam-scattered-light are provided by the system. Efforts have also been made in laser pulse shaping and laser beam transport to optimize the high-brightness electron beam production by the photocathode RF gun.  相似文献   
6.
朱江峰  杜强  王向林  滕浩  韩海年  魏志义  侯洵 《物理学报》2008,57(12):7753-7757
通过对重复频率为1 kHz的放大飞秒激光脉冲的光谱干涉实验,结合傅里叶变换进行了载波包络相位漂移的实验研究.在此基础上利用锁相环反馈控制技术实现了对载波包络相位的精密锁定,锁定后的激光脉冲稳态相位均方根误差小于80mrad,锁定时间超过3h.同时在理论上分析了光谱干涉测量放大激光脉冲载波包络相位的原理,给出了光谱干涉信号与载波包络相位的关系. 关键词: 飞秒钛宝石放大器 载波包络相位 光谱干涉 超连续  相似文献   
7.
 汤姆逊硬X射线源中,光阴极微波电子枪要求触发激光脉冲与腔中微波场相位的精确时间同步。理论分析了锁模脉冲激光器相位噪声,探讨了对激光脉冲相位探测和控制的方法,并通过实验构建了激光相位抖动测量系统和锁相环稳频回路,用基频鉴相信号驱动压电陶瓷晶体改变谐振腔长,实现了从开环3.42 ps到闭环1.46 ps的均方根相位抖动的测量和控制。  相似文献   
8.
The China Dark Matter Experiment (CDEX) is located at the China Jinping Underground Laboratory (CJPL) and aims to directly detect the weakly interacting massive particles (WIMP) flux with high sensitivity in the low mass region. Here we present a study of the predicted photon and electron backgrounds including the background contribution of the structure materials of the germanium detector, the passive shielding materials, and the intrinsic radioactivity of the liquid argon that serves as an anti-Compton active shielding detector. A detailed geometry is modeled and the background contribution has been simulated based on the measured radioactivities of all possible components within the GEANT4 program. Then the photon and electron background level in the energy region of interest (<10-2 events·kg-1·day-1·keV-1 (cpkkd)) is predicted based on Monte Carlo simulations. The simulated result is consistent with the design goal of the CDEX-10 experiment, 0.1cpkkd, which shows that the active and passive shield design of CDEX-10 is effective and feasible.  相似文献   
9.
Coherent pulse stacking(CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy and high average power. A Z-domain model targeting the pulsed laser is assembled to describe the optical interference process. An algorithm, extracting the cavity phase and pulse phases from limited data, where only the pulse intensity is available, is developed to diagnose optical cavity resonators. We also implement the algorithm on the cascaded system of multiple optical cavities,achieving phase errors less than 1.0°(root mean square), which could ensure the stability of CPS.  相似文献   
10.
 根据反射镜架系统中运动学支撑连接的物理接触形式,采用相应的位移协调方式来模拟其连接,建立了一个镜架结构的有限元模型,并分析了该镜架系统的模态及结构在地脉动载荷下的微振动分析。得到前三阶模态固有频率的最大误差小于5%,各测点的位移响应均方根的计算值与试验值吻合较好,多数点位移均方根误差控制在30%以内,且各支撑连接部位的传递特性的计算结果与试验结果比较一致,验证了所采用的运动学支撑连接的建模方法的可行性。  相似文献   
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