陶瓷样品外束质子荧光定量分析中样品定位精度的研究

通过改变与陶瓷有相似成份的GBW07306水系沉积物标准样品的前后位置和角度,研究了陶瓷样品外束质子荧光(External beam proton induced X-ray emission,外束PIXE)分析中样品位置对测量结果的影响.并以此为依据分析了陶瓷样品外束PIXE定量分析对样品定位精度的要求.结果表明:在质子能量为2.5MeV、样品距离质子引出窗口12mm和质子束入射方向夹角为30°、Si(Li)探测器在80°且距离样品20mm的实验条件下,沿束流方向位置变化引起的相对误差控制在5%以内时,样品定位精确度应高于±0.14mm;样品与质子束夹角变化引起的相对误差控制在5%以内时,样品角度定位需精确到±1.2°.     

用GUPIXWIN软件解谱的PIXE分析系统刻度

使用标准样品比较法,通过计算校正GUPIXWIN中的刻度因子H,对使用GUPIXWIN软件解谱的PIXE分析系统进行了刻度。分析了测得的H值随能量变化的原因,并用刻度后的PIXE系统分析了1组大气颗粒物样品。将GUPIXWIN分析结果与AXIL解谱的结果进行了比较,绝大多数测量结果相对偏差在±10%以内。     

GIC4117串列加速器外束PIXE/PIGE分析系统

本文介绍在北京师范大学GIC4117串列加速器上建立的外束PIXE/PIGE分析系统,和基于此系统的薄样品外束PIXE/PIGE定量分析方法。给出了2010年Teflon滤膜采集的361个气溶胶样品外束PIXE分析得到的各元素平均探测限和最低探测限,并同真空PIXE分析探测限进行了比较。利用标准样品给出了激发曲线不同坪区薄样品外束PIGE分析F和Na的探测限,通过测定¹⁹F(p, p′γ)¹⁹F激发的197 keV γ射线得到的F的探测限可达73.9 ng•cm^-2,Na的探测限可达198.9 ng•cm^-2。     

玉石及中国古代玉器的PIXE分析

本文用外束PIXE技术分析了中国古代玉器和玉石的主量、微量元素的种类和含量.实验结果表明,外束PIXE技术在判定古代玉器的玉料来源和区别不同产地玉石方面具有广阔的应用前景.     

束流变压器的基线漂移效应研究

束流变压器（BCT）在频域表现为带通特性,其低频截止特性会引起基线漂移现象,本文使用高通滤波器模型对低频截止特性对单束团和连续束团的影响进行了分析。采用基线操纵和一次谐波算法两种方法进行了基线修复,使BCT测量高重复频率连续束团的相对误差由20%下降至3%以内。     

质子非卢瑟福背散射测量气溶胶样品中氢、碳、氮和氧的含量

气溶胶样品中Z＞12以上元素含量的质子荧光(PIXE)分析是北京师范大学GIC4117串列加速器的主要应用领域之一。为弥补PIXE无法分析H、C、N和O等轻元素之不足，在PIXE靶室160°散射角安装金硅面垒探测器，用质子非卢瑟福背散射分析（PNBS）方法对核孔膜采集的气溶胶样品中H、C、N和O等轻元素的含量进行测量。测量得到的气溶胶样品中H和Si元素含量与质子前角散射（PESA）和PIXE的分析结果相近，表明PNBS可用于核孔膜采集的气溶胶样品的分析。     

矿样中钛铁EDXRF分析的基体效应和神经网络校正研究

用能量色散X荧光(EDXRF)分析仪测量钛铁矿样时,存在基体效应影响分析准确性的问题.本文用EDXRF测得钛、铁元素特征峰,通过类Gauss函数对实测谱进行拟合分解,初步分析了矿样中Ti-Fe间的影响特征.针对各元素计数率与含量的非线性关系,采用先分类后预测的方法,首先用SOFM自适应神经网络对矿样分类,样本总数80组,对铁精矿、钛精矿的识别率为100%;然后用RBF神经网络进行钛铁含量预测,与化学分析结果对比,其中65.4%的样品相对误差在1%以内,其余均在3%以内,小于工业生产仪器分析相对误差5%的要求,表明基于先分类后预测的神经网络校正技术在矿样元素含量分析中有着一定的实用价值.     

RELAP5铅铋快堆模型拓展及验证

为研究铅铋快堆瞬态热工水力特性,对RELAP5程序进行二次开发,添加铅铋合金（LBE）物性模型和液态金属流动换热模型,并与NACIE-UP和CIRCE-ICE台架的实验结果进行对比。计算结果表明：NACIE-UP台架稳态流量和温度相对误差在2%以内,瞬态相对误差不超过5%,与其他系统程序CATHARE、ATHLET、RELAP5-3D、RELAP5/MOD3.3(modified)相比,本文程序的相对偏差不超过10%;CIRCE-ICE台架稳态流量和温度相对误差在2%以内,瞬态相对误差不超过10%。本文程序满足反应堆系统热工水力分析程序精度要求,可作为铅铋快堆安全分析的有效工具。     

用弹性反冲法分析薄膜中氢含量

弹性反冲探测分析法(ERDA)是分析微量氢元素的一种新颖方法。本文介绍用该法分析薄膜中氢含量的方法、原理和初步测量结果,对VYNS膜的测量结果和PIXE法间接分析结果在±10％误差范围内相符。此方法适用于分析厚度为1～10μm的薄样品,灵敏度约为5×10~(15)at./cm~2。     

BP神经网络预测EDXRF中铁、钛元素含量

为了更好地定量分析矿石样品中铁、钛元素的含量,应用EDXRF分析技术建立了一个基于BP神经网络的预测模型。将矿石样品在EDXRF光谱仪中测得的荧光强度计数作为BP神经网络模型的输入变量,对该模型进行训练和检测。实验结果表明:该BP神经网络预测模型能获得较精确的结果,预测铁含量结果的相对误差不大于2.4%;预测钛含量结果的最大相对误差不大于2.3%;可用于地质矿石样品元素含量的分析预测。     

Beam charge integration in external beam PIXE–PIGE analysis utilizing proton backscattering with an extraction window

In this study,we present a new method for the indirect integration of beam charges in external beam proton-induced X-ray emission and proton-induced c-ray emission(PIXE–PIGE) analysis.We recorded proton spectra backscattered by a Kapton film extraction window in different sample situations and under different beam currents.We also simulated backscattering spectra using the simulation of backscattering spectra program(SIMNRA).We determined that in a specific geometrical arrangement,different sample situations did not significantly affect factor C_Q(the ratio between integral backscattering proton counts and integral beam charges).We also studied the reproducibility and beam current dependence of factor C_Q.The statistic factor of C_Q was28.95 ± 0.6 kilo counts/l C,with a relative standard deviation of 2.0 %.Significantly,in external beam PIXE–PIGE analysis,we were able to calculate beam charge integration from the integral backscattering proton counts in an energy region.     

中子粉末衍射谱仪垂直聚焦单色器的调试方法

介绍了中子散射谱仪用的中子垂直聚焦单色器的基本原理,描述了安装在中国工程物理研究院核物理与化学研究所的中子衍射谱仪的中子垂直聚焦单色器的调节方法.在样品处利用中子照相确定了束斑的中心位置和大小,通过在水平和垂直方向上的扫描得到了可利用的中子束的面积,测量了该处的最大中子注量率,结果表明在样品处得到略大于一倍的增益.     

Charge evolution and energy loss associated with electron transmission through a macroscopic single glass capillary

Charge (time) evolution and the angular dependence of incident electrons in the range 300-1030 eV through a single macroscopic glass capillary was studied. Charge measurements were done at a sample tilt angle of ψ = 2? for observation angles θ = 0? and 0.5? (both ψ and θ were measured with respect to the incident beam direction) at incident energies of 520.7 and 824.5 eV using a parallel-plate spectrometer. After equilibrium of transmission, electrons had lower average centroid (mean) energies than the respective primary beam values. Centroid energies of transmitted electrons at the centroid of the angular distribution (where the observation angle θ is nearly equal to tilt angle of the sample ψ) were found to decrease exponentially with increasing sample tilt angles for all the measured electron energies. This energy loss is attributed to inelastic scattering of electrons with the inner wall of the sample close to the capillary entrance. Furthermore, the centroid energies of the transmitted electron angular distributions at 520.7 eV were found to lose energy for angular positions away from the capillary axis (angular centroid position) for all tilt angles, indicating a higher degree of inelastic scattering at the edges of the angular distributions.     

气溶胶样品氢含量的质子弹性散射分析

利用单个标准样品比较法质子弹性散射分析（PESA）对一组采集在核孔膜上的气溶胶样品的氢含量进行定量分析。在质子束能量为2.5MeV、散射角为40°时，PESA测量10μm厚核孔膜上气溶胶中H含量的探测限为0.36μg/cm²。几个样品H含量的测量结果在3.2~37.5μg/cm²之间，显著高于探测限。质子能量在1.0~2.5MeV范围内，3.5μmMylar膜的束流归一化H峰面积随入射质子能量的变化在±3%以内。所以，不同厚度的气溶胶样品可采用同一个标准样品来进行PESA测量。     

高压型低能大功率辐照加速器电子枪研制

低能大功率辐照加速器广泛用于辐照加工产业。本工作研制出一台二极电子枪作为高压型低能大功率辐照加速器的电子源,并通过出束实验对其加以优化,最后确定了二极电子枪的最佳结构、尺寸及运行参数等。结果表明,从电子枪引出电子束的能量为5~25 keV,流强为60~100 mA,束斑为15~30 mm,半散角为0.6°~1.6°,不稳定度好于±0.6%。该电子枪工作稳定,寿命长于5 000 h。     

放射性核束17N轰击9Be和197Au靶的中子发射

用飞行时间技术测得33.4MeV/u     

Development of a new sample chamber for proton microprobe analysis of mineral samples

We describe a newly developed proton microprobe sample chamber designed for analysis of heterogeneous mineral samples. The instrument features a computer-driven stage and is equipped with novel beam and sample optics, external microscope and filter exchange system. Under the employed optical geometry, axes of beam and sample optics are collinear and normal to the sample surface, an essential aspect allowing high spatial resolution of analyses and accurate micrometer-scale sample and beam positioning. Use of a long working distance in conjunction with integral reflectance mirror are the primary design constraints satisfied for successful development. Based on measurements, the presented proton microprobe is expected to enhance studies requiring effective and easy-to-perform nondestructive microanalytical analysis of minerals.     

中子垂直聚焦单色器的调试

中子聚焦单色器可有效提高中子散射谱仪样品处的中子注量率。对安装在中国工程物理研究院核物理与化学研究所的中子衍射谱仪中子垂直聚焦单色器进行调节，在样品处利用中子照相确定了束斑的中心位置和大小，通过在水平和垂直方向上的扫描得到了可利用的中子束的面积，测量了该处的最大中子注量率。在样品处得到略大于1倍的增益。这一结果表明，调试是成功的。     

A segmented conical electric lens for optimization of the beam spot of the low-energy muon facility at PSI: a Geant4 simulation analysis

The low-energy muon facility at PSI provides nearly fully polarized positive muons with tunable energies in the ke V range to carry out muon spin rotation(LE-μSR)experiments with nanometer depth resolution on thin films,heterostructures, and near-surface regions. The low-energy muon beam is focused and transported to the sample by electrostatic lenses. In order to achieve a minimum beam spot size at the sample position and to enable the steering of the beam in the horizontal and vertical direction, a special electrostatic device has been implemented close to the sample position. It consists of a cylinder at ground potential followed by four conically shaped electrodes,which can be operated at different electric potential. In LE-μSR experiments, an electric field at the sample along the beam direction can be applied to accelerate/decelerate muons to different energies(0.5–30 keV). Additionally, a horizontal or vertical magnetic field can be superimposed for transverse or longitudinal field μSR experiments. The focusing properties of the conical lens in the presence of these additional electric and magnetic fields have been investigated and optimized by Geant4 simulations. Some experimental tests were also performed and show that the simulation well describes the experimental setup.     

On the optimization of an external PIXE arrangement

An external PIXE arrangement where the PIXE measurements can be normalized directly by the collected beam charge is presented. In the arrangement presented the beam current measurement was shown to be independent of the sample material by comparing the K-peak intensities of the Ar component of the air with the collected beam charges. In addition, a simple vacuum safety valve for the breakdown of the exit foil is presented and the importance of effective sample cooling and proper choice of exit foil material is emphasized.