A theoretical model for calculating the full-energy peak efficiency of scintillator detector is proposed in this paper. The effective penetration distance of gamma-rays in & Oslash;3.81cm x 3.81 cm LaBr3(Ce) 3 (Ce) crystal, aluminum shell and MgO reflector is analyzed. The calculation model for point source detection efficiency is derived, and the attenuation of gamma-rays in the detector shell is computed by theoretical calculation method. This method is used to calculate the efficiency of LaBr3(Ce) 3 (Ce) with a size of & Oslash;3.81 x 3.81 cm for detecting gamma-rays from point sources of 137 Cs and 60 Co located in different positions. Compared with experimental data and Monte Carlo (MC) simulation results, the maximum relative deviation is less than 5%. The attenuation of gamma-rays with an energy of 60 keV is more than 50%. The fitted efficiency calibration curve in the energy range of 60 keV-1500 keV is in good agreement with the simulation results. The results show that this method is suitable for calculating the efficiency of the LaBr3(Ce) 3 (Ce) detector using point sources, especially for analyzing low-energy gamma ray sources. By taking into account the attenuation of the gamma-rays by the detector shell, the measurement accuracy can be effectively improved. The proposed method can be extended for the efficiency calibration of scintillator detectors with various shapes and provides a new approach for 'source-less' efficiency calibration of detectors.

[Background]Efficiency calibration is an important prerequisite for γ-spectroscopy measurement,and its accuracy directly affects the reliability of measurement results.The commonly used efficiency calibration methods are active efficiency calibration based on experimental measurement and passive efficiency calibration based on Monte Carlo(MC)simulations.[Purpose]This study aims to propose a sourceless efficiency calibration method for γ spectrum based on numerical analysis.[Methods]Based on theoretical analysis and numerical calculation,a passive efficiency calibration method based on numerical analysis was established,and applied to a constructed geometric model for typical cylindrical LaBr3(Ce)and NaI(Tl)detector with a diameter and length of 3.8 cm.The γ-ray path trajectory inside the detector,relative position of the source and detector,and peak-to-total ratio were comprehensively analyzed.Efficiency formulas for radioactive point,surface,and volume radioactive sources were formulated.Then,a numerical integration program based on Simpson's algorithm was implemented in MATLAB to solve the numerical analytical formula,and applied to the calculation of detection efficiencies of the 3.8 cm cylindrical LaBr3(Ce)and NaI(Tl)detectors for isotropic 137Cs point,surface,and volume sources.The calculation was performed again by changing the position of the point source and the size of the surface and volume sources.Simultaneously,the Monte Carlo(MC)simulation software MCNP5 was employed to establish the physical model of the detector,and the F8 pulse amplitude card was used to calculate the detection efficiency of the detector for specific energy γ-rays.Finally,detection efficiency obtained by numerical calculation was compared with that of MC simulation to verify the efficiency of proposed sourceless efficiency calibration method for γ spectrum.[Results]Compared with the MC simulation results,the maximum error of numerical calculation does not exceed 3.5%,and the maximum relative errors of the point source efficiency,surface source efficiency and volume source efficiency are 3.26%,3.33%and 3.36%,repectively,which proves the reliability and accuracy of the numerical analysis method in calculating the detection efficiency.[Conclusions]The passive efficiency calibration method proposed in this study is accurate and fast,avoids complicated MC simulation software,which tends to be difficult to understand and operate.Additionally,this work can be extended to the efficiency calibration of nuclear radiation detectors with different shapes,providing a new pathway for the efficiency calibration of detectors.

采用MC法对圆柱形几何体中土壤样品的探测效率进行计算,评估了 46～2615 keV范围内的自吸收修正因子.研究了样品密度、高度和湿度等参数对自吸收因子的影响,并得到了相应的修正函数.研究结果表明,对于特定能量的γ光子,样品密度的变化对自吸收的影响最大;对于与标准样品密度相差不大的样品,应重点考虑高度、湿度的变化对自吸收带来的影响;在对含低能量γ光子放射性核素的样品测量时,应综合考虑密度、高度和湿度带来的误差.综合分析了土壤样品密度、高度和湿度等因素对γ自吸收的影响及修正函数,可对计算复杂基质下土壤样品的自吸收效应提供参考.

综述了多种平滑方法的基本原理及使用方法.使用多种平滑方法分别对NaI(Tl)γ谱仪所测同一能谱进行平滑滤波处理,利用Matlab软件对平滑后的能谱数据进行处理,并与原始能谱进行比较.引用了平滑度指标,对比分析了单一平滑方法对γ能谱的平滑能力.将能谱分为不同能区,找到了适宜的平滑方法.结果表明:针对NaI(Tl)γ谱仪所测能谱,在低能区域和高能区域宜使用小波法和高斯法进行平滑,在中能区域使用傅里叶变换法平滑效果最佳.

BackgroundWhen the relative position of the point source and the detector changes, the detection efficiency will also change. Determining the functional relationship of the detection efficiency with the alteration of the detection distance and angle is beneficial to quickly obtain the detection efficiency of the point source at any position.PurposeThis study aims to determine the spatial point source efficiency function for a LaBr3(Ce) of a specific size.MethodsThe detection efficiency of 152Eu, 137Cs, and 60Co point sources at specific positions were simulated and calculated by MCNP5, and the efficiency of the 3.81-cm (diameter and length) LaBr3(Ce) detector was calibrated by simulation. The detection efficiency of the point source at different positions in the 2π space range of the front of the LaBr3(Ce) detector was calculated. The functional relationship between detection efficiency and angle and distance was obtained by data fitting.ResultsCompared with the experimental results, the maximum relative difference of detection efficiency of point sources calculated by MCNP5 is less than 6%. The maximum detection efficiency of LaBr3(Ce) detector appears at an angle of 90° with the detector axis. With the increase of detection distance and energy, the influence of angle on the detection efficiency of point source gradually decreases. The effect of the spatial position on the detection efficiency is actually the spatial solid angle efficiency of the point source relative to the detector.ConclusionThe detection efficiency of a point source at any position in space can be calculated based on the efficiency function, which has a good reference value and guiding significance for the solution of the LaBr3(Ce) detector efficiency matrix and the efficiency calibration.

The detection efficiency of soil samples in a cylindrical measuring geometry was calculated using the Monte Carlo method, evaluating the self-absorption corrections in the energy range of 46-2615 keV. By controlling variables, the effects of parameters such as sample density, height and humidity on the self-absorption factor have been studied, and the corresponding correction functions have been obtained. The research results show that: for γ photons of a specific energy, the change of sample density has the greatest impact on self-absorption. For samples whose density is not much different from that of the standard sample, the impact of changes in height and humidity on self-absorption should be considered. In the high-precision measurement of samples containing low-energy γ-photon radionuclides, the errors caused by density, altitude and humidity should be comprehensively considered.

根据在涂硼CsI(Tl)探测器中产生的γ射线、中子脉冲信号的特征,利用电荷比较法、上升时间法、频率梯度法、向量投影法、聚类分析法、神经网络法完成了n/γ射线甄别.结果 表明了这些方法均可以实现对涂硼CsI(Tl)探测器的中子甄别,这为今后搭建涂硼CsI(Tl)探测器的中子实时甄别系统打下基础.

随着工业时代的到来，越来越多的工业技术逐步发展，工业生产的需求使得自动化技术获得良好的创新和提升，在机械制造业通过自动化技术能够大幅度的提升工作效率，在机械工程中，使机械生产效率提升明显，保证了机械生产的综合质量，对于企业提升经济效益具有积极作用。

随着经济发展速度的不断提升，我国的科学技术产业发展速度也十分客观，在机械工程行业内容发展成果也十分明显，毋庸置疑自动化技术在机械工程的发展过程中取得了良好的效果。采用自动化技术能够有效的提升整体工程的运行效率，降低工程开展时间，提供工程操作质量，同时在经济效益方面也获得极大的提升。本文首先对机械自动化技术概述进行分析，同时对我国目前的自动化技术应用情况产生的原因进行分析，进而分析机械工程中自动化技术的应用情况，最后对机械工程中自动化技术应用前景进行展望。

目的 在意外中子照射情况下,研究人体受到的中子照射剂量与固定测最条件下的计数率的关系.方法 测量人体血液中的元素23Na在热中子活化作用下生成的放射性同位素24Na衰变时的γ光子计数来估算人体受照剂量.结果 在获得的血液样品的γ谱中,能够清晰地获得24Na的含有本底的特征峰和去本底的特征峰,通过解谱可降低本底中40K的1.461MeV的γ峰的干扰,其计数不确定度均小于10%.结论 简化了测量步骤,提高了测量速度,适用于快速为中子受照人员的医学救治提供具有较高可信度的剂量学数据.

ObjectiveTo estimate the neutron dose using 24Na energy spectrum analysis method.MethodsGenius-2000 GeomComposer software package was used to calibrate the efficiency of the detector.Results The detection efficiency of the detector toward γ photon with an energy of 1.368 MeV was quickly found to be 4.05271×10-2 while the error of the software was 4.0%.The estimated dose value of the neutron irradiation samples was between 1.94 Gy and 2.82 Gy,with an arithmetic mean value of 2.38 Gy.The uncertainty of the dosimetry was about 20.07%.ConclusionThe application of efficiency calibration without a radioactive source to the energy spectrum analysis of the 24Na contained in human blood will accelerate the estimation process.