基于单光电倍增管液闪计数器的缪子信号符合消除方法研究

摘要/Abstract

摘要： 液体闪烁测量作为一项放射性核素活度检测技术,具有灵敏度高、探测效率高和操作简单等优点,被广泛应用于大气、水体、土壤和生物等样品中低能核素(如¹⁴C、³H和⁵⁵Fe等)的活度测量。在测量过程中,由于本底事件(如缪子)的干扰导致测量结果偏大,从而影响最终分析结果。基于此,提出了一种双路信号符合的方法消除本底事件中的缪子信号,该方法基于快响应光电倍增管(PMT)具有保留信号时间的良好特性,对快响应PMT最后一级打拿极输出的β信号进行标记,和缪子信号进行符合消除。通过标记的β信号控制开关通断,实现快响应PMT阳极输出β信号的选通。利用¹⁴C液闪样品进行实验验证,结果表明:缪子信号和β信号衰减时间有明显差异,典型缪子信号衰减时间为154.4 ns,典型β信号衰减时间为41.6 ns,且缪子信号的衰减时间在80 ns以上,β信号的衰减时间介于10~80 ns之间;采用此方法能够有效地消除缪子信号。研究工作可为便携式低能β核素活度的精准测量提供参考。

关键词: 液闪测量技术, 低能核素, 缪子, 符合法

Abstract: As a radioactive nuclide activity detection technique with advantages such as high sensitivity, high detection efficiency, and simple operation, liquid scintillation measurement is widely used for measuring the activity of low-energy nuclides (e.g., ¹⁴C, ³H, and ⁵⁵Fe) in samples from the atmosphere, water bodies, soil, and biological specimens. During the measurement process, interference from background events (e.g., muons) leads to inflated results, thereby affecting the final analysis. To address the above problem, this paper proposes a dual-channel signal coincidence method to eliminate muon signals from background events. This method leverages the favorable signal time-preserving characteristics of fast-response photomultiplier tubes (PMTs). It marks the β signal output from the last dynode of the fast-response PMT and applies coincidence rejection to the muon signal. The marked β signal controls the switching of a gate, enabling the gating of the β signal output from the PMT anode. Experimental verification was conducted using ¹⁴C liquid scintillation samples. The results show a significant difference in the decay times between muon signals and β signals. The typical decay time for muon signals is 154.4 ns, while for β signals it is 41.6 ns. Specifically, muon signal decay times exceed 80 ns, whereas β signal decay times fall within the 10~80 ns range. The proposed method effectively eliminates muon signals. This research can serve as a reference for the accurate measurement of portable low-energy β nuclide activity.

Key words: liquid scintillation measurement technique, low-energy nuclides, muon, coincidence method

中图分类号:

张鹏鹏, 李德源, 王林靖, 张宣汝, 加德拉·库阿尼别克, 李华. 基于单光电倍增管液闪计数器的缪子信号符合消除方法研究[J]. 辐射防护, 2026, 46(1): 1-9.

ZHANG Pengpeng, LI Deyuan, WANG Linjing, ZHANG Xuanru, Jiadela Ku′anibieke, LI Hua. Study on the method of eliminating muon signals by coincidence technique based on a single photomultiplier liquid scintillation counter[J]. RADIATION PROTECTION, 2026, 46(1): 1-9.

参考文献

[1] 张金卫.探测超微发光的 FJ-2115液体闪烁计数器[J].核电子学与探测技术,1992,12(06):370-371.
ZHANG Jinwei. FJ-2115 automatic liquid scintillation counter[J]. Nuclear Electronics & Detection Technology, 1992, 12(6): 370-371.
[2] Cook, Gordon T.Recent development and applicaiton in liquid scintillation counting. Recent advances and environmental applications in liquid scintillation spectrometry[J].Analytical Proceedings, 1992, 29(1):4-6.
[3] Temple S. Liquid scintillation counting: how has it advanced over the years and what does the future hold?[J]. Bioanalysis. 2015,7(5):503-505.
[4] Hanslík E, Marešová D, Juranová E, et al. Comparison of balance of tritium activity in waste water from nuclear power plants and at selected monitoring sites in the Vltava River, Elbe River and Jihlava (Dyje) River catchments in the Czech Republic[J]. Journal of Environmental Management.2017,203(3):1137-1142.
[5] Oztürk E, Yesilova Z, Ilgan S, et al. A new, practical, low-dose 14C-urea breath test for the diagnosis of Helicobacter pylori infection: clinical validation and comparison with the standard method[J]. European Journal of Nuclear Medicine and Molecular Imaging, 2003, 30(11): 1457-1462.
[6] Sharma B C, Bhasin D K, Pathak C M, et al.[14C] -urea breath test to confirm eradication of Helicobacter pylori[J]. Journal of Gastroenterology and Hepatology, 1999, 14(4): 309-312.
[7] Yoon Y Y, Cho S Y, Lee K Y, et al. Radiochemical determination of uranium and radium isotope in natural water using liquid scintillation counter[J]. Journal of Radioanalytical and Nuclear Chemistry, 2013, 296(1): 397-402.
[8] Dizman S, Keser R. A comparison of two methods used for determination of tritium concentration in urine samples by liquid scintillation counter[J]. Radiation Detection Technology and Methods, 2018, 2(1): 23.
[9] Dorman L I.Cosmic rays in the earth′s atmosphere and underground[M].Springer Netherlands, 2004.DOI:10.1007/978-1-4020-2113-8.
[10] Rossi B, Greisen K. Cosmic-ray theory[J]. Reviews of Modern Physics, 1941, 13(4): 240-309.
[11] 梁烨,吴英,杨斌,等.基于Geant4低本底液闪谱仪屏蔽与反符合设计[J].核科学与工程,2019,39(4):666-671.
LIANG Ye, WU Ying, YANG Bin, et al. Shield and anti-coincidence design of the low background liquid scintillation spectrometer based on Geant 4[J]. Nuclear Science and Engineering, 2019, 39(4): 666-671.
[12] 赵震. 基于Geant4的低本底液闪谱仪设计[D]. 北京: 华北电力大学(北京), 2022.
ZHAO Zhen. Design of low-background liquid scintillation spectrometer based on Geant4[D]. Beijing: North China Electric Power University (Beijing), 2022.
[13] Piraner O, Jones R L. The effect of quench agent on urine bioassay for various radionuclides using QuantulusTM1220 and Tri-CarbTM3110[J]. Journal of Radioanalytical and Nuclear Chemistry, 2020, 326(1): 657-663.
[14] 安小刚, 唐泉, 丘寿康, 等. 1220 QuantulusTM PSA值优化设置及其准确性检验实验研究[J]. 南华大学学报(自然科学版), 2014, 28(3): 22-25.
AN Xiaogang, TANG Quan, QIU Shoukang, et al. Study on optimization setting and accuracy test of the PSA value for 1220 QuantulusTM LSC[J]. Journal of University of Souht China (Science & Technology), 2014, 28(3): 22-25.
[15] PerKin Elmer Life Sciences. Wallac 1220 Quantulus^TM ultra low level liquid scintillation spectrometer[R]. Turku: Perkin Elmer Life Sciences, 2002.
[16] Aso T, Masuda T, Hara M, et al. Study of counting efficiency with triple to double coincidence ratio in liquid scintillation counter by using geant4[C] //2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC). Atlanta: IEEE, 2017: 1-4.
[17] 荻原清, 加藤结花, 吉村共之, 等. 超低本底液体闪烁谱仪的高性能化追求[J]. 国际放射医学核医学杂志, 2015, 39(3): 273-276.
DI Yuanqing, Kato Y, Yoshimura T, et al. Pursuit of high performance in ultra-low background liquid scintillation spectrometers[J]. International Journal of Radiation Medicine and Nuclear Medicine, 2015, 39(3): 273-276.
[18] Rittirong A, Noithong P, Hazama R, et al. Determination of tritium levels in tap waters collected from various regions in Thailand using liquid scintillation counting[J]. Journal of Physics: Conference Series, 2019, 1285(1): 012021.
[19] 宋有学, 李永明, 刘国伟. Hidex 300SL液闪装置测量氚水活度的参数优化[C] //首届中国氚科学与技术学术交流会. 成都: 中国核学会, 2015: 252.
SONG Youxue, LI Yongming, LIU Guowei, et al. Parameter optimization of Hidex 300SL liquid scintillation counter for tritiated water activity measurement[C] //The first China academic conference on tritium science and technology. Chengdu: Chinese Nuclear Society, 2015: 252.
[20] Krapiec M, Walanus A. Application of the triple-photomultiplier liquid spectrometer HIDEX 300 SL in radiocarbon dating[J]. Radiocarbon, 2011, 53(3): 543-550.
[21] Wanke C, Kossert K, Nähle O J. Investigations on TDCR measurements with the HIDEX 300 SL using a free parameter model[J]. Applied Radiation and Isotopes: Including Data, Instrumentation and Methods for use in Agriculture, Industry and Medicine, 2012, 70(9): 2176-2183.
[22] 邓艾芳, 董振芳, 石红旗, 等. LSA 3000液闪谱仪测量低水平氚水活度的参数优化[J]. 海洋环境科学, 2019, 38(1): 89-92, 105.
DENG Aifang, DONG Zhenfang, SHI Hongqi, et al. Parameter optimization of ultra low background liquid scintillation spectrometer LSA 3000 for low-level tritium determination in water samples[J]. Marine Environmental Science, 2019, 38(1): 89-92, 105.
[23] 艾艳, 郭勇, 高超, 等. 超低本底液闪谱仪测量装置: CN205787153U[P]. 2016-12-07.
AI Yan, GUO Yong, GAO Chao, et al. Ultra-low background liquid flash spectrometer measuring device: CN205787153U[P]. 2016-12-07.
[24] 郭勇, 艾艳, 孙刚, 等. 一种低本底液体闪烁谱仪测量装置: CN205301597U[P]. 2016-06-08.
GUO Yong, AI Yan, SUN Gang, et al. A low-background liquid scintillation spectrometer measuring apparatus: CN205301597U[P]. 2016-06-08.
[25] L'Annunziata M F, Tarancón A, Bagán H, et al. Chapter 6-liquid scintillation analysis: principles and practice[M] //L'Annunziata M F. Handbook of Radioactivity Analysis. 4th ed. Pittsburgh: Academic Press, 2020: 575-801.
[26] 唐泉. 液闪测氚法在重水提氚工艺试验中的应用及其质量控制研究[D]. 衡阳: 南华大学, 2005.
TANG Quan. The liquid the application and quality scintillation method for tritium determination in the technological text on separating tritium from heavy water[D]. Hengyang: University of South China, 2005.
[27] ZHANG Pengpeng, LI Deyuan, LI Hui, et al. Single-photon elimination in liquid scintillation counting with pulse shape discrimination and delayed coincidence[J]. Radiation Measurements, 2024, 178: 107299.