高温气冷堆球流检测系统中CsI(Tl)探测器温度影响研究
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摘要
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8pA。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)℃。
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 32 nd unit reaches 8 pA when the temperature fluctuate is ±2 ℃ at the room temperature.Therefore,a specialized temperature con-trolling 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)℃.
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 32 nd unit reaches 8 pA when the temperature fluctuate is ±2 ℃ at the room temperature.Therefore,a specialized temperature con-trolling 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)℃.
引文
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[2]JAEGER H M,NAGEL S R.Physics of the granular state[J].Science,1992,255:1 523-1 531.
[3]Pebble Bed Modular Reactor Limited.PBMR safety analysis report,001929-207/4[R].South Africa:PBMR,1999.
[4]朱敦志.高温气冷反应堆球形燃料元件流动过程理论与实验研究[D].北京:清华大学,1991.
[5]KADAK A C,BAZANT M Z.Pebble flow experiments for pebble bed reactors[C]∥Proceeding of the 2th International Topical Meeting on High Temperature Reactor Technology.Beijing:[s.n.],2004.
[6]X-ray pebble recirculation experiment design and initial experimental results,UCBTH-15-002[R].Berkeley:UC Berkeley,2014.
[7]刘锡明,吴志芳,丛鹏,等.用于PB-HTGR燃料球运动规律研究的钴-60螺旋CT系统研发[J].CT理论与应用研究,2015,24(2):283-289.LIU Ximing,WU Zhifang,CONG Peng,et al.Research on cobalt-60 spiral CT studying fuel sphere’s motion law in PB-HTGR[J].CT Theory and Applications,2015,24(2):283-289(in Chinese).
[8]CHAVANELLE J,PARMENTIER M.A CsI(Tl)-PIN photodiode gamma-ray probe[J].Nuclear Instruments and Methods in Physics Research A,2003,504(1):321-324.
[9]IKAGAWA T,KATAOKA J,YATSU Y,et al.Study of large area Hamamatsu avalanche photodiode in aγ-ray scintillation detector[J].Nuclear Instruments and Methods in Physics Research A,2005,538(1):640-650.
[10]IKAGAWA T,KATAOKA J,YATSU Y,et al.Performance of large-area avalanche photodiode for low-energy X-rays andγ-rays scintillation detection[J].Nuclear Instruments and Methods in Physics Research A,2003,515(3):671-679.
[11]SATO R,KATAOKA J,KANAI Y,et al.Development of 2cm-square Hamamatsu avalanche photo diodes for high-resolution X-rays andγ-rays detection[J].Nuclear Instruments and Methods in Physics Research A,2006,556(2):535-542.
[12]张催,李公平.CsI(Tl)光电二极管探测器模拟研究[J].无损探伤,2014,38(6):12-16.
[13]杨世明,龚光华,邵贝贝,等.PIN硅光电二极管用于γ射线探测的试验研究[J].核技术,2006,29(8):573-576.YANG Shiming,GONG Guanghua,SHAO Beibei,et al.Experimental study of PINγphotodiode for ray detection[J].Nuclear Techniques,2006,29(8):573-576(in Chinese).
[14]何景棠,毛裕芳,董晓黎,等.CsI(Tl)晶体的辐射损伤研究[J].高能物理与核物理,1997,21(1):21-24.HE Jingtang,MAO Yufang,DONG Xiaoli,et al.Experimental studies on radiation damage of Cs(Tl)crystals[J].High Energy Physics and Nuclear Physics,1997,21(1):21-24(in Chinese).
[15]朱永生,陈宇,史焕章,等.国产CsI(Tl)晶体辐照损伤实验研究[J].高能物理与核物理,1998,22(10):865-872.ZHU Yongsheng,CHEN Yu,SHI Huanzhang,et al.Experimental studies on radiation damage of China made CsI(Tl)crystals[J].High Energy Physics and Nuclear Physics,1998,22(10):865-872.