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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
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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
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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
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受端区二次流的影响,叶片前缘和压力面根部角区端壁难以实现有效冷却。为了实现该区域的冷气覆盖,本文研究了新型冷却结构离散台阶缝的端区气膜冷却特性。离散台阶缝在叶片周向主要覆盖叶片前缘区域,能够集中冷气冷却换热恶劣的区域。本文研究了两种不同离散台阶缝轴向位置(AP1,AP2)和三种不同冷气量(MFR=0.43%,0.88%,1.33%),通过红外热像仪测量端区气膜冷却效率分布。结果表明,增加离散台阶缝与叶片的轴向距离,能够有效提高叶片上游区域的冷却效果,但在通道内部,结果相反。增加冷气量能够提高端壁的气膜冷却效果。此外,应用五孔探针测量叶栅通道喉部附近截面二次流流场特征,解释了通道冷却分布的机理。 相似文献
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本文对文献[1]中关于测谎仪的概率计算做了进一步的分析,从数据中得出了不合理的结论,并对其做出了解释。本文从新的角度出发来阐述,利用平均错判率为指标,而且指出了概率计算中的三个动态因素;实际的说谎概率、所谓的敏感度及特异性。 相似文献
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