A fully digital data acquisition system based on a field-programmable gate array(FPGA) was developed for a CsI(Tl) array at the external target facility(ETF) in the Heavy Ion Research Facility in Lanzhou(HIRFL). To pr...A fully digital data acquisition system based on a field-programmable gate array(FPGA) was developed for a CsI(Tl) array at the external target facility(ETF) in the Heavy Ion Research Facility in Lanzhou(HIRFL). To process the CsI(Tl) signals generated by γ-rays and light-charged ions, a scheme for digital pulse processing algorithms is proposed. Every step in the algorithms was benchmarked using standard γ and α sources. The scheme, which included a moving average filter, baseline restoration, leading-edge discrimination, moving window deconvolution, and digital charge comparison, was subsequently implemented on the FPGA. A good energy resolution of 5.7% for 1.33-MeV γ-rays and excellent α-γ identification using the digital charge comparison method were achieved, which satisfies CsI(Tl) array performance requirements.展开更多
In this study,we constructed two annular detector arrays comprising 24 wedge-shaped CsI(Tl) crystals,and tested them using anαsource and radioactive beams of ^(14-16) Con a CD_2 target.We compared the properties of a...In this study,we constructed two annular detector arrays comprising 24 wedge-shaped CsI(Tl) crystals,and tested them using anαsource and radioactive beams of ^(14-16) Con a CD_2 target.We compared the properties of a CsI(Tl) crystal encapsulated with various reflectors,revealing that using the 80-μm-thick ESR film to pack the CsI(Tl) crystal yielded the largest light output with the smallest non-uniformity in light output (ΔLO).For the 24 CsI(Tl) detectors with the 80-μm-thick ESR films,the average energy resolution improved as the average light output increased;however,it deteriorated as theΔLO value increased.To form two annular Si-CsI(Tl) telescopes for identifying the light-charged particles,theΔLO value and energy resolution of each CsI(Tl) detector were maintained under 20%and 7.7%,respectively.These telescopes were tested for the first time in a direct nuclear reaction experiment using ^(14-16) C+d.The results demonstrated that the Z=1 and Z=2 charged particles were adequately discriminated by the telescopes using the standardΔE-E method.展开更多
为满足不同应用场景对环境γ辐射监测的需求,完善区域监测产品体系,本文开展了一种基于CsI(Tl)闪烁体的γ射线环境剂量当量监测仪的研制工作,基于结构紧凑、成本可控、响应稳定等设计目标实现了探测器的原理与结构设计及原理样机制造。...为满足不同应用场景对环境γ辐射监测的需求,完善区域监测产品体系,本文开展了一种基于CsI(Tl)闪烁体的γ射线环境剂量当量监测仪的研制工作,基于结构紧凑、成本可控、响应稳定等设计目标实现了探测器的原理与结构设计及原理样机制造。使用蒙特卡洛粒子输运程序(Monte Carlo N-Particle Transport Code,MCNP)构建高精度的仿真模型,分别在实验与模拟条件下使用标准γ辐射场开展剂量响应测试与仿真,对比验证了该仿真模型的可靠性(灵敏度误差小于5%)。针对CsI(Tl)闪烁体本征能谱响应的非线性问题,基于脉冲幅度分段赋权法开发了能量响应补偿技术,经该技术补偿后变异系数小于6%,能量响应晃动小于12%,有效提升了剂量当量测量的准确性。结果表明,本研究方法可在显著改善CsI(Tl)探测器的能量依赖性的同时无需进行能谱展开,为其他类型剂量监测设备提供一种低成本、高可靠性的校准技术路径。展开更多
The thallium-doped ces sium iodide(CsI(Tl))scintilla-tor is widely used in the fields of nuclear physics,nuclear medicine,safety inspection,for the characteristics of high density,high luminous efficiency,high radiati...The thallium-doped ces sium iodide(CsI(Tl))scintilla-tor is widely used in the fields of nuclear physics,nuclear medicine,safety inspection,for the characteristics of high density,high luminous efficiency,high radiation-hardness,low cost,etc[1-3].展开更多
介绍了配置于新型γ能谱仪的CsI(Tl)闪烁探测器的读出电路设计。输入缓冲级采用折叠嵌位电路,改善了系统频率特性并提高了输入阻抗;放大级采用自举电路,改善了系统动态性能并提高了开环增益;输出级采用电流源负载电路,改善了输出信号的...介绍了配置于新型γ能谱仪的CsI(Tl)闪烁探测器的读出电路设计。输入缓冲级采用折叠嵌位电路,改善了系统频率特性并提高了输入阻抗;放大级采用自举电路,改善了系统动态性能并提高了开环增益;输出级采用电流源负载电路,改善了输出信号的线性度并增强了系统的稳定性。实验表明:读出电路噪声为51.08 f C+1.97 f C/p F,时间漂移为0.112%,探头对137Cs源γ射线的输出信号信噪比可达23:1,能量分辨率可达4.98%。展开更多
由闪烁体和光电转换器件构成的闪烁体探测器是工业CT系统中最常用的探测器,其中闪烁体负责将X射线转换为可见光信号,再经过光电转换器件转换为电信号进行探测.闪烁体作为探测器的一部分,其厚度直接影响发光效率和探测分辨性能.本文基于...由闪烁体和光电转换器件构成的闪烁体探测器是工业CT系统中最常用的探测器,其中闪烁体负责将X射线转换为可见光信号,再经过光电转换器件转换为电信号进行探测.闪烁体作为探测器的一部分,其厚度直接影响发光效率和探测分辨性能.本文基于蒙特卡罗仿真平台Geant4建立仿真模型,对碘化铯Cs I(Tl)闪烁体在不同厚度、不同X射线能量(20~80 ke V)下的特性进行模拟,分析闪烁体厚度对闪烁体转换效率以及分辨力的影响.通过仿真获了特定输入能量下对应的闪烁体的理想厚度值.仿真结果可以为闪烁体参数设计和优化提供参考.展开更多
基金supported by the Open Research Project of CAS Large Research InfrastructuresCAS Key Technology Talent ProgramNational Natural Science Foundations of China (Nos.U2031206 and 12273086)
文摘A fully digital data acquisition system based on a field-programmable gate array(FPGA) was developed for a CsI(Tl) array at the external target facility(ETF) in the Heavy Ion Research Facility in Lanzhou(HIRFL). To process the CsI(Tl) signals generated by γ-rays and light-charged ions, a scheme for digital pulse processing algorithms is proposed. Every step in the algorithms was benchmarked using standard γ and α sources. The scheme, which included a moving average filter, baseline restoration, leading-edge discrimination, moving window deconvolution, and digital charge comparison, was subsequently implemented on the FPGA. A good energy resolution of 5.7% for 1.33-MeV γ-rays and excellent α-γ identification using the digital charge comparison method were achieved, which satisfies CsI(Tl) array performance requirements.
基金supported by the National Natural Science Foundation of China (Nos.12275007, U1867214, 11775004)the funding from the State Key Laboratory of Nuclear Physics and Technology,Peking University,China (No. NPT2021ZZ01)funding from heavy Ion Research Facility,Lanzhou,China (No. HIR2021PY002)。
文摘In this study,we constructed two annular detector arrays comprising 24 wedge-shaped CsI(Tl) crystals,and tested them using anαsource and radioactive beams of ^(14-16) Con a CD_2 target.We compared the properties of a CsI(Tl) crystal encapsulated with various reflectors,revealing that using the 80-μm-thick ESR film to pack the CsI(Tl) crystal yielded the largest light output with the smallest non-uniformity in light output (ΔLO).For the 24 CsI(Tl) detectors with the 80-μm-thick ESR films,the average energy resolution improved as the average light output increased;however,it deteriorated as theΔLO value increased.To form two annular Si-CsI(Tl) telescopes for identifying the light-charged particles,theΔLO value and energy resolution of each CsI(Tl) detector were maintained under 20%and 7.7%,respectively.These telescopes were tested for the first time in a direct nuclear reaction experiment using ^(14-16) C+d.The results demonstrated that the Z=1 and Z=2 charged particles were adequately discriminated by the telescopes using the standardΔE-E method.
文摘为满足不同应用场景对环境γ辐射监测的需求,完善区域监测产品体系,本文开展了一种基于CsI(Tl)闪烁体的γ射线环境剂量当量监测仪的研制工作,基于结构紧凑、成本可控、响应稳定等设计目标实现了探测器的原理与结构设计及原理样机制造。使用蒙特卡洛粒子输运程序(Monte Carlo N-Particle Transport Code,MCNP)构建高精度的仿真模型,分别在实验与模拟条件下使用标准γ辐射场开展剂量响应测试与仿真,对比验证了该仿真模型的可靠性(灵敏度误差小于5%)。针对CsI(Tl)闪烁体本征能谱响应的非线性问题,基于脉冲幅度分段赋权法开发了能量响应补偿技术,经该技术补偿后变异系数小于6%,能量响应晃动小于12%,有效提升了剂量当量测量的准确性。结果表明,本研究方法可在显著改善CsI(Tl)探测器的能量依赖性的同时无需进行能谱展开,为其他类型剂量监测设备提供一种低成本、高可靠性的校准技术路径。
文摘The thallium-doped ces sium iodide(CsI(Tl))scintilla-tor is widely used in the fields of nuclear physics,nuclear medicine,safety inspection,for the characteristics of high density,high luminous efficiency,high radiation-hardness,low cost,etc[1-3].
文摘介绍了配置于新型γ能谱仪的CsI(Tl)闪烁探测器的读出电路设计。输入缓冲级采用折叠嵌位电路,改善了系统频率特性并提高了输入阻抗;放大级采用自举电路,改善了系统动态性能并提高了开环增益;输出级采用电流源负载电路,改善了输出信号的线性度并增强了系统的稳定性。实验表明:读出电路噪声为51.08 f C+1.97 f C/p F,时间漂移为0.112%,探头对137Cs源γ射线的输出信号信噪比可达23:1,能量分辨率可达4.98%。
文摘由闪烁体和光电转换器件构成的闪烁体探测器是工业CT系统中最常用的探测器,其中闪烁体负责将X射线转换为可见光信号,再经过光电转换器件转换为电信号进行探测.闪烁体作为探测器的一部分,其厚度直接影响发光效率和探测分辨性能.本文基于蒙特卡罗仿真平台Geant4建立仿真模型,对碘化铯Cs I(Tl)闪烁体在不同厚度、不同X射线能量(20~80 ke V)下的特性进行模拟,分析闪烁体厚度对闪烁体转换效率以及分辨力的影响.通过仿真获了特定输入能量下对应的闪烁体的理想厚度值.仿真结果可以为闪烁体参数设计和优化提供参考.
