BH1307型康普顿散射谱仪的屏蔽优化

北京核仪器厂生产的BH1307型康普顿散射仪使用较强的γ放射源,该放射源放置在专门的铅屏蔽室内。当屏蔽室处于关闭状态时,检测到明显的环境辐射。利用Na(I Tl)闪烁谱仪对屏蔽室周围的辐射环境进行能谱测量,发现与初始γ射线能量不同的射线。经分析认为:屏蔽室侧面的辐射来源于γ射线的透射,强度稍弱;屏蔽室正前方的辐射主要来源于γ射线与内部材料发生近90°康普顿散射后,经过出射孔出射,强度较强;建议铅屏蔽室尤其是正前方出射孔位置在关闭状态时也要加以防护。     

HPGe低本底反康普顿γ谱仪

本文报道了以ＨＰＧｅ为主探测器的低本底反康普顿γ谱仪，该谱仪以环形和圆柱形ＮａＩ（ＴＩ）组成阱型反符合屏蔽探测器，以钢，铅及不锈钢等材料组成复合结构屏蔽室。对＾４０Ｃｏ１３３２．５ｋｅＶγ射线，ＨＰＧｅ主探测器能量分辨率为１．８６ｋｅＶ，相对效率为３８％，在阱型反符合屏蔽条件下，谱仪对＾１３７Ｃｓ点状薄膜源测得康普顿抑制系数为４．４；峰康比为８７０：１；５０￣２０００ｋｅＶ能区内每ｍｉｎ积分本底为     

采用联反符合计数系统的康普顿抑制γ谱仪

本文介绍的用于低本底γ测量的小型康普顿抑制谱仪采用并联取样反符合计数系统，同时具有简单有效的物质屏蔽和数据自动采集和分析功能，在阱型反符合屏蔽条件下，谱仪对置于ＮａＩ（Ｔｌ）主探测器上方３．５ｃｍ处的＾１３７Ｃｓ薄膜源的探测灵敏度为７４．３７Ｐａ；在５０－２０００ＫｅＶ能区的积分本底为１５ｍｉｎ＾－１，与无反符合屏蔽时相比降低了６１．５％。     

低本底反康普顿HPGe γ谱仪的调试

本文报道的低本底反康普顿ＨＰＧｅγ谱仪．ＨＰＧｅ探测器对￣（６０）Ｃｏ的１３３２ｋｅｖγ射线的相对探测效率为３８．３％．能量分辨率为１．７７ｋｅＶ。在阱型反符合屏蔽下．对放在探测器端面的￣（１３７）Ｃｓ点状薄膜源的峰康比可达６８５．８：１；测量时间１００ｍｉｎ．置信度９５％时．￣（１３７）Ｃｓ点源的最小判断限为１．１２ｘ１Ｏ￣（－４）Ｂｑ。在物质屏蔽和阶型反符合屏蔽下，在５０～２１５２．８ｋｅＶ能区的积分本底为０．３４３ｓ￣（－１）。与无反符合屏蔽时相比，压缩系数大于４．５．对￣（１５２）Ｅｕ体源，谱仪积分非线性为０．０２７％。     

γ射线康普顿散射的能谱研究

利用10 mCi的137Cs放射源发出的662 keV的γ射线,开展了与铝棒材料的康普顿散射实验。在20°～120°散射角度范围,用NaI(Tl)闪烁能谱仪直接测量获得了散射射线的能谱。简要介绍了实验原理和装置,给出了与实验系统配套的探测效率、峰总比等数据,深入讨论了散射射线能谱的特征,获得了散射能量、散射截面与散射角度的关系,并与理论值进行了比较,验证了康普顿散射理论。最后评述了该种康普顿散射能谱测量的方法。     

一套低本底反康普顿HPGe γ谱仪十年运行回顾

介绍了一套低本底反康普顿高纯锗(HPGe)γ谱仪系统的基本组成、工作原理和主要技术指标,回顾了谱仪运行十年来主要指标的变化情况,介绍了10年来基于该谱仪所开展的主要工作和取得的重要成果,展望了谱仪广阔的应用前景.     

两套低本底反康普顿HPGeγ谱仪技术指标的比较

以对比的手法介绍了两套结构相同的低本底反康普顿高纯锗γ谱仪在技术指标,性能上的差别,并通过详实的实验数据,对谱仪处在不同工作状态时的康普顿散射抑制效果作了细致的比较,分析了影响提高峰康比的主要因素。     

低本底反康普顿HPGeγ谱仪能量分辨率影响因素分析

简述了低本底反康普顿HPGe(高纯锗)γ谱仪系统构成与工作原理,主要分析了影响系统能量分辨率技术指标的诸因素,提出了系统最佳配置原则,为购置、安装及调试系统提供了决策依据.     

康普顿散射谱仪的自动控制

介绍了利用计算机对由高纯锗探测器、放大器和多道分析器组成的康普顿散射谱仪系统进行自动控制的结构和原理。通过对氧化物、金属、纳米材料等样品的测量,结果显示该系统的长期漂移小于0．05％,不仅提高了测量精度,也节省了测量时间,并且其原理同样也适用于类似的长时间、高精度的放射性测量系统中。     

一套低本底反康普顿HPGeγ谱仪系统积分本底的实验研究

本文对一套低本底反康普顿HPGeγ谱仪系统的积分本底进行了实验研究,测量了谱仪系统在无屏蔽、屏蔽室以及屏蔽室加反符合三种条件下的积分本底.结果表明,谱仪系统积分本底主要来源于康普顿连续坪区和40K核素1460keVγ射线全能峰.实验确定了40K主要来自NaI (Tl)环探测器的六个光导玻璃窗及光电倍增管,两者所含40K总的放射性活度约为612Bq.     

Image reconstruction from Compton scattering data

A new image reconstruction method was developed for a Compton camera. A simulation to determine a γ-ray source position was performed by using the simulation tool, GEANT4. An image reconstruction was made in two steps. First, a three dimensional image was constructed and projected in one selected plane, then the points from each ellipse was picked up by taking the peak points of a density distribution of crossing points between the ellipse and the first step image. The second step procedure improved the accuracy and the spatial resolution of a position determination significantly, comparing with the image obtained by only the first step. The accuracy and the resolution for a point source were obtained to be about 0.02 mm and (1.35 0.15) mm, respectively. The same procedure was applied to an imaging of the distributed y-ray source.     

激光同步辐射源特性的线性康普顿散射分析

激光同步辐射源（Laser Synchrotron Source,简称LSS）是利用强激光与相对论电子束散射,产生准单色、能量可调的X射线脉冲的新型X射线源。本文介绍了LSS的线性康普顿散射理论;分析了LSS的主要特性,包括X射线通量、脉冲时间结构、能谱等。     

Experimental study of proton scattering on carbon

Measurement of inelastic scattering cross sections of 8 MeV protons on carbon has been carried out in the 30-170° angular range. The excitation functions for the 1.73 MeV-resonance have been measured in the 1-2 MeV energy range at 110°, 115° and 150°. Measurements of the excitation functions have been compared with previous measurements and Gurbich evaluation.     

An empirical expression for total scattering cross sections of normal hydrocarbons, and experimental total cross sections of C2H2 and C3H4

The total electron scattering cross sections (TCS) of C₂H₂ and C₃H₄ have been obtained for 200-4500 eV electrons by measuring the attenuation of the electron beam through a gas cell. An empirical expression is deduced to express the TCS of normal hydrocarbons as a function of the number of atomic constituencies in the hydrocarbon and the electron energy.     

Measurements of the elastic scattering cross sections for proton on T, He

The cross sections for the elastic scattering of protons from tritium at 151° and from helium at 155° angles in the laboratory frame, over the energy range of 1.2-3.4 MeV, have been measured in the present work, as a supplement to previous cross section measurements determined at different scattering angles recently. The currently measured cross section data are compared to data available in literature. The cross section enhancement was also investigated for both reactions. It was found that over the whole measured energy range, the elastic cross section for protons on tritium increases linearly with energy and is about 1000 times greater than the Rutherford cross section at 3.4 MeV. On the other hand, in the case of the elastic scattering of protons from helium, the cross section below 2.3 MeV increases almost linearly, and reaches a maximum of about 300 mb/str at the energy of 2.4 MeV for the scattering angle of 165°, and then, after this energy, it keeps oscillating around the maximum.     

Differential elastic scattering cross sections of protons from Al in 2.4–4.8 MeV energy range

Measurement of differential elastic cross section of protons from aluminum was taken at 165° degree in the2.4–4.8 Me V energy range. The results and measured energy resonances were compared with reported measurements.These data will improve the reliability of backscattering analysis of Al with protons in this energy region.     

Cu-Ni和Fe-Cu合金中Cu含量与康普顿散射光子数的关系

从理论上推导了康普顿散射光子数与合金中某成分含量间的关系表达式,经分析可近似为线性关系。然后,按一定成分制备好Cu-Ni和Fe-Cu两组合金,从实验上验证了Cu-Ni和Fe-Cu两组合金中Cu含量和康普顿散射光子数间的线性关系。最后作了详尽讨论,拟进一步开拓康普顿散射的应用领域。     

A revised additivity rule for electron scattering from ethylene, propene, butene, ethane, propane and butane

Considering the difference between the bound atom in a molecule and the free atom, the original additivity rule is revised. Using the revised additivity rule, the total cross sections for electron scattering by ethylene (C₂H₄), propene (C₃H₆), butene (C₄H₈), ethane (C₂H₆), propane (C₃H₈) and butane (C₄H₁₀) are calculated over the energy range 10-1000 eV. The results of the revised additivity rule are compared with those obtained by experiments and the revised additivity rule can give better agreement with experimental values than the original additivity rule.