基于Monte-Carlo模拟和峰形拟合的CdZnTe探测器G(E)函数简便计算方法研究

提出了一种简便的CdZnTe探测器能谱-剂量转换函数(G(E)函数)的计算方法。峰形拟合函数被用于表征CdZnTe探测器对γ射线的低能拖尾,峰形拟合函数的参数通过实验测量获取,并通过拟合得到其随能量变化的关系。Monte-Carlo模拟计算得到的探测器理想沉积谱,经峰形拟合函数卷积得到了修正的模拟能谱,修正的模拟能谱与实际测量能谱吻合较好。基于修正的模拟能谱计算得到了CdZnTe探测器的G(E)函数。标准辐射场中的实验结果表明,用G(E)函数加权积分计算的周围剂量当量率与约定真值基本一致。     

SOI 硅微剂量探测器对中子和伽马辐射场线能谱测量的GEANT4模拟研究

绝缘体上硅(SOI)硅微剂量测量系统可以通过测量中子和伽马混合辐射场的线能谱来获取不同类型辐射的剂量当量贡献。本文根据SOI硅微剂量探测器物理设计,采用GEANT4软件建模对Cf-252中子和伽马混合辐射场及Co-60伽马辐射线能谱测量进行蒙特卡罗模拟,并进一步分析了SOI探测器转换层对伽马线能谱测量的影响。结果表明,SOI硅微剂量探测器能够区分中子和伽马的剂量贡献,并且伽马线能谱峰值随着转换层厚度发生变化,有可能利用该特性实现不同贯穿深度下伽马辐射剂量贡献的测量。模拟分析结果可为SOI硅微剂量探测器设计及应用提供参考。     

低本底β计数-α能谱测量装置

本文介绍了一种为远洋现场调查而研制的低本底β计数-α能谱测量装置。该测量装置能同时进行低活度的β测量和α能谱分析,克服了用两套仪器分别测量β计数和α能谱的麻烦,并减小了测量误差。     

HT-7超导托卡马克上γ辐射的初步研究

尝试了在HT-7托卡马克准稳态等离子体实验平台上，对伽马辐射能谱与通量进行测量与分析。实验中，测量得到了不同放电条件下的伽马辐射能谱和通量的时间演化过程，观测到了丰富的伽马辐射行为。针对欧姆加热、低杂波、离子回旋波、离子伯恩斯坦波、长脉冲等不同放电条件下的伽马辐射行为做了研究，结合其它相关诊断数据，给出了初步的分析结果。     

铀矿伽马能谱测井核脉冲信号数字化处理技术

在铀矿勘查中,可采用伽马能谱测井获取钻孔地层的铀、钍含量。相对于传统的模拟构架,基于数字化核脉冲信号处理技术构建的伽马能谱测井仪具有计数率高、信号噪声低和稳定性好等优点。通过采用核脉冲信号数字化处理技术,实现了伽马能谱的数字化采集,在放射性勘查模型井上进行了测试。混合模型的能谱测量铀、钍含量与标称含量的误差均小于5%,符合铀矿伽马能谱测井相关规范要求。     

采用自然伽马能谱测井仪研究天然放射性元素的高度和深度分布规律

尝试提出将自然伽马能谱测井仪用于生态环境的研究。对自然伽马能谱测井仪、地面伽马能谱、室内分析、航空伽马能谱测量的同一地点钍、铀、钾元素含量进行对比分析得知,各种方法所得结果具有较好的一致性。通过16口浅层自然伽马能谱测井资料分析黄河三角洲浅层放射性的区域变化状况。研究发现,随着石油勘探开发程度的深入,浅层钍、铀、钾元素含量随之增高。将所采集的数据与地壳中钍、铀、钾元素含量的平均值进行比较,得出黄河三角洲地区的钍、铀、钾元素含量普遍较低的结论。     

核测井伽马能谱探测器的测量不确定度评定

对核测井伽马能谱探测器的测量不确定度进行评定,建立了数学模型,找出构成测量不确定度的要素和分量组成,分析得出探测器的能量分辨率为8.958%,相对合成标准不确定度为1.065%,k=1。按照评定结果判断,探测器可以保证伽马能谱测井仪的正常使用。     

核设施退役现场γ污染测量技术研究

在核设施退役中,放射性污染源项的确定是十分重要的基础工作。其中,利用装置和相关技术对污染核素、污染水平、污染热点进行现场直接测定是一项关键性技术。本课题采用1台HPGeγ谱仪,利用准直、实验刻度和蒙特卡罗方法计算相结合的技术,确定了现场污染设备的污染核素及污染水平。同时,建立了1套γ污染扫描和热点定位装置,经利用准直、摄像、步进测量技术,从而很好地实现了在不靠近污染设备和周围辐射干扰很强的条件下,对γ污染核素及其水平的测定。其研究成果可以在退役活动源项测量中发挥很好的作用。核设施退役现场γ污染测量技术研究@…     

虚拟仪器在核物理实验中的应用

介绍了利用虚拟仪器技术在核物理实验中的几种应用:包括基于GPIB总线构成的对ORTEC974或994定标器进行计算机控制,实现D-T反应伴随α粒子数的分时测量;基于PCI总线构成的控制数据采集卡对BC501A液体闪烁体的脉冲信号进行采集,经处理得到中子伽马的分辨谱与质子和电子的反冲能谱,对反冲谱进行解谱得到中子伽马能谱;基于PCI总线构成的控制数据采集卡进行快信号逐脉冲采集,获得测量能谱.软件采用LabVIEW编程,极大减轻了软件开发的工作量.     

小型CZT探测器测量浓缩厂铀富集度的实验研究

CZT（CdTe或CdZnTe）是一种新型化合物半导体探测器，用于γ射线能谱测量时，其能量分辨率介于HPGe探测器和NaI（T1）探测器之间。由于这种探测器具有体积小、重量轻、能在室温下长时间工作，易做成小型便携式测量装置等优点，因此，在核保障现场核查中得到了广泛应用。     

基于LabVIEW的γ相机成像系统软件设计

在核设施的去污、退役过程中,提供放射性核素的空间分布及＂热点＂是首要解决的任务,γ相机是完成上述任务的重要工具之一。本文介绍一套γ相机成像系统软件设计的部分内容：数字化核辐射数据的存储、实时散点图及＂热点＂成像的实现方法。     

Research of CdZnTe detector based portable energy dispersive spectrometer

A kind of excellent CdZnTe crystal has been grown in Yinnel Tech, Inc. in recent years. Based on these CdZnTe crystals and some new techniques, a portable energy-dispersive spectrometer has been constructed which has yielded good results. CdZnTe detector has a 3% relative resolution in high-energy field and can detect gamma rays at room temperature. An integrated circuit based on preamplifier and shaping amplifier chips is connected to the detector. Voltage pulses are transformed into digital signals in MCA （multichannel analyzer） and are then transmitted to computer via USB bus. Data process algorithms are improved in this spectrometer. Fast Fourier transform （FFT） and numerical differentiation （ND） are used in energy peak＇s searching program. Sampling-based correction technique is used in X-ray energy calibration. Modified Gaussian-Newton algorithm is a classical method to solve nonlinear curve fitting problems, and it is used to compute absolute intensity of each detected characteristic line.     

Gamma spectrometry inspection of TRIGA MARK II fuel using caesium isotopes

Gamma spectrometry is one of the common methods to inspect the spent fuel from research reactors. This method has been applied to in-pool measurements of the Spent Fuel Elements (SPEs) of the TRIGA Mark II research reactor. Due to mixed nature of the reactor core and complicated irradiation history of the fuel elements (FEs), the gamma spectrometry of the FE establishes improvements in the calculation and measurement of the SPE. In order to inspect the TRIGA SPE from dry storage and cooled fuel from the reactor pool, the selected spend fuels are scanned and measured using the fuel-scanning machine. Gamma spectrometry is performed by HPGe detector for spend fuel inspection and determination of the ¹³⁷Cs activity and ¹³⁴Cs/¹³⁷Cs ratio. In this work, the steps of the detector calibration and the use of the Monte Carlo radiation transport code (MCNP5) have been described. In addition, the fuel-scanning machine and the gamma spectrometer are modelled by MCNP5 to simulate the gamma transport from fuel to detector. It also simulate the gamma spectrometer calibration for the burn up determination of the spend fuel. The results from MCNP5 simulation are applied to spectroscopic measurements and compared with the theoretical predictions of the neutronics code ORIGEN2 in this research work.     

大面积流气式电离室的研制及性能测试

核设施退役过程中,超铀核素放射性样品的无损测量一般通过γ能谱法实现,但由于超铀核素的γ射线发射几率一般较低,因此这种测量方法的探测限较高,不适用于溶解后低水平放射性样品的测量。本工作建立的大面积流气式电离室,通过探测α粒子电离空气的原理进行多孔样品的间接无损测量,方法探测限低,可以分析放射性活度低至百Bq级别的样品板。     

地层元素测井技术最新进展及其应用

地层元素测井是一种通过测量中子与地层元素原子核作用放出的伽马射线,得到元素含量进而确定矿物含量的中子伽马能谱测井技术,在复杂储层岩性识别、非常规储层评价等方面得到了广泛应用。本文简要介绍了元素能谱测井的核物理和地质基础,并对元素俘获能谱测井（ECS）、地球化学测井（GEM）和地层岩性能谱测井（FLS）等几种仪器技术指标进行分析;系统讨论了确定元素含量的谱分析技术及矿物含量的氧化物闭合模型和统计分析方法;总结了元素能谱测井在地层评价中的应用。最后提出采用可控中子源和多探测器系统、多参数测量是地层元素测井的发展趋势。     

核设施退役辐射检测及其仪器仪表应用

核设施退役辐射场检测技术在核设施退役的整个过程中起着非常重要的作用.较系统论述了核设施退役辐射检测的质量保证,最后从满足核设施退役工作的需要出发,评述了退役过程辐射检测仪器仪表的选择及其应用.指出国内辐射监测仪器仪表在满足核设施退役的需求上的较大差距,值得各有关方面关注.     

Application of the Monte Carlo method to the analysis of measurement geometries for the calibration of a HP Ge detector in an environmental radioactivity laboratory

A gamma spectrometer including an HP Ge detector is commonly used for environmental radioactivity measurements. The efficiency of the detector should be calibrated for each geometry considered. Simulation of the calibration procedure with a validated computer program is an important auxiliary tool for environmental radioactivity laboratories. The MCNP code based on the Monte Carlo method has been applied to simulate the detection process in order to obtain spectrum peaks and determine the efficiency curve for each modelled geometry. The source used for measurements was a calibration mixed radionuclide gamma reference solution, covering a wide energy range (50-2000 keV). Two measurement geometries - Marinelli beaker and Petri boxes - as well as different materials - water, charcoal, sand - containing the source have been considered. Results obtained from the Monte Carlo model have been compared with experimental measurements in the laboratory in order to validate the model.     

基于FPGA和ARM的便携式γ谱仪研制

为适应γ能谱分析的发展需要,研发了新型便携式γ谱仪。该谱仪引入了FPGA技术,取代时序复杂的分立数字器件,增强了仪器的可维护性,更具适用性;开发了基于ARM的界面友好的多道采集软件,摆脱了依赖于计算机操作的限制,且仪器工作时间大于8h,因而可用于长时间野外测量。测试结果表明:该谱仪能量分辨率为6.9%,稳定性为0.3%,满足了γ谱仪的性能指标要求。     

CdZnTe quasi-hemispherical detector for gamma–neutron detection

Quasi-hemispherical CdZnTe detector was manufactured successfully to fully understand the performance in the mixed gamma–neutron detection field. Together with the software of COMSOL, Geant4, and Matlab, the detector structure has been optimized. The CdZnTe detector performs good energy resolutions for ²⁴¹Am, ⁵⁷Co, and ¹³⁷Cs radiation sources, especially for ¹³⁷Cs (10.91 keV full width at half maximum [FWHM] at 662 keV). A linear relationship between the energy positions and spectrum channels indicates that the detector is effective for the precise energy detection from 59.5 to 662 keV. Finally, neutron and gamma events were detected simultaneously at room temperature using ²⁴¹AmBe neutron source. The spectrum shows good energy resolution for neutron capture gamma ray (14.28 keV FWHM at 558 keV). Our work demonstrates that the quasi-hemispherical CdZnTe detector is promising for simultaneous detection of neutrons and gamma radiation.     

HPGe γ谱仪测量级联γ辐射152Eu、133Ba、60Co核素活度的方法

给出了HPGe γ谱仪测量级联γ辐射核素活度的一种实用方法,在探测器与样品之间放置一定厚度的水吸收层,能够很好降低探测效率,显著降低级联γ符合效应和偶然符合效应的影响。实验表明,TC-45样品中¹⁵²Eu、¹³³Ba、⁶⁰Co核素活度的探测效率和测量活度相对偏差随水吸收层厚度增加遵循指数衰减规律,当厚度增加到70 mm以上,其测量活度相对偏差小于4%。