高温气冷堆球流检测系统中CsI(Tl)探测器温度影响研究

为保证球床式高温气冷堆（PB-HTGR）球流检测系统投影数据获取过程中输出信号的稳定性，需对探测模块输出暗电流的稳定性进行分析。本文随机选取了2组CsI(Tl)探测器模块作为研究对象，并专门设计了温度及暗电流的控制和测量装置，分析了模块暗电流的输出特性及其控制要求。实验结果表明：各探测单元输出暗电流随温度的变化呈近似指数变化，且室温下温度波动±2 ℃时第32路单元的暗电流波动达8 pA。因此需对探测系统进行温度控制，同时分析实验数据并结合暗电流稳定性的控制要求，提出检测系统的最佳温控范围为（18~22） ℃，对应的温控精度为（±0.92~±0.21） ℃。

Study of Temperature Influence on CsI(Tl) Detector in High Temperature Gas-cooled Reactor Pebble-flow Detection System

In order to ensure the output signal stability of pebble-flow detection system for pebble-bed high temperature gas-cooled reactor (PB-HTGR) during the projection acquisition process, the analysis for dark current stability of detector module is required. In this paper, two sets of CsI(Tl) detector modules were randomly selected and a corresponding controlling and measuring device for temperature and dark current was designed. In addition, the dark current characteristic of the detector module and the controlling requirement were analyzed. Experimental results show that the change of dark current with temperature by each detector unit is approximately exponential. Besides, the dark current fluctuate of the 32nd unit reaches 8 pA when the temperature fluctuate is ±2 ℃ at the room temperature. Therefore, a specialized temperature controlling system for the detection system is to be adopted inevitably. Combining the experimental result with dark current controlling requirement, an optimal temperature controlling range is (18-22) ℃, and the corresponding temperature controlling precision is (±0.92±0.21) ℃.