闪烁体-光纤组合式辐射探测器γ相对灵敏度研究

根据光纤光导的耦合理论,推导了闪烁体-光纤组合式探测器γ灵敏度理论公式,计算了LSO、 ST401两种闪烁体-光纤探测器的相对灵敏度,在平均能量为1.25 MeV的60Co射线源上测得10 mm厚LSO闪烁体-光纤组合式探测器的灵敏度是相同厚度ST401的19倍,理论计算和实验结果在不确定度范围内一致.     

光电倍增管线性电流扩展研究

根据对光电倍增管工作原理的分析,介绍了目前提高光电倍增管线性电流的方法,分析了不同类型的非线性效应.基于数字化示波器的应用和数据处理技术,提出了利用实验数据,通过数值校正的方法扩展光电倍增管的线性电流.利用线性电流大的光电管与光电倍增管进行比较,对光电倍增管通过校正,可以使光电倍增管的最大线性电流扩展5倍以上.     

ICCD相机动态范围与空间分辨率

采用二级级联简化模型和探测量子效率理论推导了ICCD相机最小可探测光子数与增益、调制传递函数之间的关系,理论结果表明相机动态范围随分辨率的增加而减小,实验测量了空间分辨率为5 lp/mm和3.1 lp/mm时相机的动态范围,与理论结果符合较好。     

时间分辨型ICCD成像系统研制

ICCD成像系统是将像增强器耦合到CCD上,以获得更高的信号增益、更高的信噪比和更大的动态范围。通过电子快门控制像增强器开启时间实现时间分辨。介绍了时间分辨型ICCD成像系统的组成和研制,给出了系统的性能参数。系统在放大倍数为1的情况下,物面空间分辨率优于5 lp/mm,相机的动态范围为38.7倍,同步精度2 ns,时间分辨为5 ns。     

双包层紫外光纤伽马辐照效应实验研究

双包层大芯径紫外石英光纤具有高的传输效率和耐辐照性,在核辐射场信号传输与测量中有良好的应用前景。但在核辐射场中,光纤受辐照会产生发光和诱导损耗,影响测量精度和准确度。为此,建立了光纤辐照损耗和发光光谱测量系统及方法,对芯径为0.2、0.4和0.6mm石英光纤在辐照剂量率为0.053 6Gy/s的稳态60 Co伽马射线源上进行了测量。实验结果表明:芯径越大,光纤辐照产生的附加损耗越小;辐照附加损耗并非与总剂量呈正比,随着辐照时间和总剂量的增加,损耗值增量逐渐减小;发光和损耗与光的波长有关,短波区光纤发光强度和损耗较长波区大;实验测量得到了0.6mm光纤在300~600nm的发光光谱,发光强度约为10~(-13)W·s/(Gy·m);相同时间内,不同波长辐照恢复效果不同,长波长损耗小,较快恢复到辐照前光纤传输效率,而短波长损耗大,恢复较慢。     

Optical Diagnostics of Multi-Gap Gas Switches for Linear Transformer Drivers

The trigger characteristics of a multi-gap gas switch with double insulating layers,a square-groove electrode supporter and a UV pre-ionizing structure are investigated aided by a high sensitivity fiber-bundle array detector, a UV fiber detector, and a framing camera, in addition to standard electrical diagnostics. The fiber-bundle-array detector is used to track the turn-on sequence of each electrode gap at a timing precision of 0.6 ns. Each fiber bundle, including five fibers with different azimuth angles, aims at the whole emitting area of each electrode gap and is fed to a photomultiplier tube. The UV fiber detector with a spectrum response of 260-320 nm,including a fused-quartz fiber of 200 μm in diameter and a solar-blinded photomultiplier tube, is adopted to study the effect of UV pre-ionizing on trigger characteristics. The framing camera,with a capacity of 4 frames per shot and an exposure time of 5 ns, is employed to capture the evolution of channel arcs. Based on the turn-on light signal of each electrode gap, the breakdown delay is divided into statistical delay and formative delay. A decrease in both of them, a smaller switch jitter and more channel arcs are observed with lower gas pressure. An increase in trigger voltage can reduce the statistical delay and its jitter, while higher trigger voltage has a relatively small influence on the formative delay and the number of channel arcs. With the UV pre-ionizing structure at 0.24 MPa gas pressure and 60 kV trigger voltage, the statistical delay and its jitter can be reduced by 1.8 ns and 0.67 ns, while the formative delay and its jitter can only be reduced by 0.5 ns and 0.25 ns.