内充气正比计数管测量37Ar活度中壁效应的理论研究

通过分析³⁷Ar衰变产生的X射线和俄歇电子在内充气正比计数管灵敏体积中的逃逸及计数管在³⁷Ar活度测量中的壁效应,得出X射线在正比计数管中的逃逸是产生壁效应的主要原因,提出了压力指数外推方法。使用MCNP模拟X射线和俄歇电子在内充气正比计数管中的输运,模拟结果与理论分析结论一致。比较模拟得出的壁效应值与实验测量的壁效应值可知,实验给出的壁效应值是可信的。本工作的研究结果为37Ar测量方法提供了理论支持。     

正比计数管探测低能X射线时探测效率的MC计算

为研究各因子对正比计数管探测低能X射线时性能的影响,利用MCNP5软件计算了不同光子能量下管内气体种类、气体压强及壁效应、放置距离等因素对探测器探测效率的响应情况。结果表明正比计数管探测器对10~30 ke V X射线探测效率最佳;且在探测低能X射线时,正比计数管应尽可能靠近源项,同时管内最佳气体压强在1.515×105~2.02×105Pa之间。     

无损检测用加速器束流稳定性分析系统的研制

介绍了单道脉冲幅度分析系统对电子直线加速器每个宏脉冲内产生的电子束流稳定性的实时测量方法和对打靶产生的X射线剂量率进行动态监测的分析处理系统的研制与开发。介绍了单道分析器的原理和硬件组成。后端软件使用面向对象的Visual C^ .net开发完成，软件采用图形化软面板，所有控制和结果显示在计算机屏幕上。系统具有可靠性好、精度高、测量直观、应用软件的界面友好等优点。     

X射线正比计数管的使用

X射线正比计数管是一种气体型的X射线探测器件,它工作在气体放电正比区,有气体放大现象,因而信噪比高。和闪烁探测器相比,能量分辨率好,允许在较高计数率下工作,对低能X射线有较高的探测效率。因此,X射线正比计数管是探测低能X射线和γ射线的能量和强度的良好探测器。     

硅漂移探测器电子温度测量系统研制

在2005年HL-2A实验中,我们首次采用两通道硅漂移探测器(Silicon Drift Detector,SDD)软X射线能谱系统对等离子体电子温度进行了测量。文章详细地介绍了SDD软X射线能谱测量系统的原理、设计和初次运行,给出了HL-2A电子温度的测量结果。结果表明,SDD非常适合于HL-2A电子温度测量,为在HL-2A上建立多通道SDD阵列测量电子温度分布奠定了坚实的基础。     

Z箍缩X射线源辐射场理论分析

利用Z箍缩等离子体辐射源产生X射线可开展脉冲X射线辐照材料动力学响应及热力学效应研究,而试验面处的辐射功率密度是热力学效应研究中最关心的参数。本文针对Z箍缩产生的软X射线辐射功率密度场分布,以理论分析和数值模拟为手段,将Z箍缩软X射线辐射源分别等效为线光源和朗伯辐射光源,获得了2种等效情况下X射线辐射功率密度场的分布。分析表明,在线光源等效情况下,远场分布为球面分布,符合距离平方反比关系,而近场则近似圆柱面分布,符合距离反比关系;在朗伯辐射光源等效情况下,远场分布为球面余弦调制分布,而近场分布近似圆柱面分布。等效模型分析结果均表明：对于长度为2 cm的Z箍缩软X射线辐射体,当试验样品放置位置距离Z箍缩光源大于5 cm后,试验面处的辐射功率密度即可视为远场情况,符合距离平方反比关系。     

米曲霉孢子对同步辐射C、N、O元素K吸收边附近软X射线的吸收剂量分布研究

以C、N、O元素的K吸收边附近能量的软X射线为辐射光源,通过模型分析,比较了米曲霉孢子不同部位对不同能量软X射线吸收剂量分布.同时利用合肥同步辐射软X射线显微术光束线准单色的软X射线对孢子进行辐照实验,对不同能量辐照存活率结果进行了比较.理论分析表明,由于C、N、O元素K吸收边效应以及孢子不同部位元素组成的不同,受照时孢子不同部位对软X射线的吸收剂量分布随能量变化存在差异.实验结果显示,3种元素K吸收边附近软X射线对米曲霉孢子均有很强的辐射失活效应,其中2.3nm波长的软X射线对孢子的辐射损伤效应要高于3.2nm和4.4nm波长的软X射线.     

X射线荧光分析中原级谱分布的计算

X射线荧光分析中,X射线管产生的原级谱的分布对荧光分析的影响很大。尤其是在元素间吸收增强效应的校正过程中,基本参数法要求准确获得X射线原级谱的强度分布。使用MCNP程序模拟不同加速电压、不同靶材料、不同铍窗厚度等条件下电子打靶后的X射线能谱分布,为X射线荧光分析仪研制过程优化X光管靶材、管压等提供依据,实现高精度的X射线荧光分析。     

基于X射线相干衍射成像的元素分布成像

基于上海光源软X射线谱学显微线站的特点和相干X射线衍射成像(CDI)技术,对软X射线相干衍射成像方法的一个重要应用:元素分布成像及含量分析进行了模拟研究。推导了CDI相比双能分析算法并进行了理论模拟,估算了能够分辨的最小物质含量,并分析了CDI实验噪声等因素对元素分布成像的影响。所得结果可对软X射线CDI的实际应用提供理论指导。     

铍窗正比计数管的制造、性能及其应用

正比计数管是测量核辐射的一种基本探测元件。在测量X射线和低能γ射线时,和闪烁计数器比较,在两者的探测效率大体相同的情况下,正比计数管具有较高的能量分辨本领,并且能够测量较低的能量。因此,在X射线和低能γ射线(<100keV)的测量方面,正比计数管获得广泛的应用。     

Unfolding of Ge-detector response by Monte Carlo simulation and applications in radiation protection

Response functions to monoenergetic gamma radiation of a portable high purity Ge-detector have been calculated by Monte Carlo simulation for 180 photon energies ranging from 20 keV to 1.5 MeV and used to unfold measured pulse height spectra. The dependence of response functions on scattering from housing and cryostat of the detector and on the incidence angle of the radiation is discussed. Measured pulse height spectra in a house exposed to a ⁶⁰Co source were unfolded and compared to photon fluence rate spectra obtained by a Monte Carlo simulation of the photon transport in this environment, finding a very good agreement.     

Calculation of the pulse height distribution and counting efficiency of a fast neutron scintillation detector

An efficient method was developed for calculating the pulse height distribution from a scintillation detector irradiated by monoenergetic neutrons. The method was based on the separation of the pulse height distribution conlributions from single and multiple neutron scattering by nuclei of the scintillator material. The contribution from single scattering was computed analytically, and that from multiple scattering by the Monte-Carlo method, The new method is considerably more precise than the usual Monte-Carlo method.Consideration was given to a number of effects which were neglected in previous work.The computations performed were mainly designed to obtain information about fast neutron spectra from experimental data.Translated from Atomnaya Énergiya, Vol. 15, No. 3, pp. 194–200, September, 1963     

仿核脉冲的随机信号发生器研究

以伪均匀随机数为基础,通过算法产生高斯分布和指数分布随机数,以89C51单片计算机系统为硬件,采用Keil C编程,实现了输出脉冲幅度可以是高斯分布、指数分布及均匀分布等模式,也可以两种以上模式共同输出,输出脉冲时间间隔可以是周期性的,也可以是指数分布的。该随机信号发生器可以实现多种分布模式的输出控制,较好的仿真了核脉冲幅度和时间的随机特性。     

The Degradation of Solar Cells under Van Allen Radiation

The electrons and protons of the Van Allen Belt cause radiation damage to silicon solar cells which results in a gradual reduction of the power output of solar power plants on satellites passing through the Belt. The study of the radiation damage caused by monoenergetic electrons and by monoenergetic protons of various energy indicates that N on P solar cells are substantially more radiation resistant than the commonly used P on N cells. From such studies and a knowledge of the composition of the Van Allen Belt, a flux of, for example, 1 Mev electrons can be determined that will cause the same radiation damage per unit time to a bare solar cell as the Van Allen Belt spectrum would produce under a given shielding. Observations of radiation damage on satellites are also conveniently expressed in terms of such an equivalent flux. Measurements of solar cell short circuit current changes and changes in the current gain of specially designed highly radiation sensitive transistors have been performed on the Telstar satellite. The results are in general agreement with the radiation damage expected from the observed particle flux and they indicate that solar power is practical for long-life satellites passing through the Van Allen Belt, particularly if N on P solar cells are used.     

The design of “multiple energies from one source” in D-T neutron tube

To obtain multiple monoenergetic neutron sources and realize the on-site calibration of radiation monitoring equipment for nuclear-involved places,the structural characteristics and neutron source features of D-T neutron tube were analyzed;Monte Carlo method was adopted to simulate the effect of interaction between typical materials and different energy neutrons;multilayered shielding materials were combined and optimized to acquire the optimal scheme to shield the neutron sources from the neutron tube.On the base,a tapered alignment filtration construction was designed and Monte Carlo method was employed to simulate the effect of alignment construction.The result showed that the tapered alignment filtration construction can create monoenergetic neutrons including14.1 MeV,0.18 MeV and thermal neutrons and demonstrated good monochrome performance which provides multiple monoenergetic sources for the on-site calibration.     

A new digital Gaussian pulse shaping algorithm based on bilinear transformation

Nuclear pulse signal needs to be transformed to a suitable pulse shape to remove noise and improve energy resolution of a nuclear spectrometry system. In this paper, a new digital Gaussian shaping method is proposed.According to Sallen-Key analog Gaussian shaping filter circuits, the system function of Sallen-Key analog Gaussian shaping filter is deduced on the basis of Kirchhoff laws. The system function of the digital Gaussian shaping filter based on bilinear transformation is deduced too. The expression of unit impulse response of the digital Gaussian shaping filter is obtained by inverse z-transform. The response of digital Gaussian shaping filter is deduced from convolution sum of the unit impulse response and the digital nuclear pulse signal. The simulation and experimental results show that the digital nuclear pulse has been transformed to a pulse with a pseudo-Gaussian, which confirms the feasibility of the new digital Gaussian pulse shaping algorithm based on bilinear transformation.     

两种深空核爆炸辐射电磁脉冲模型的比较

深空核爆炸通过电偶极子和磁偶极子两种辐射机制产生电磁脉冲。本文具体分析了两种辐射模型产生电磁脉冲的物理机制,并估算了远处观察点的辐射电场。计算表明,电子以高斯波形出射时,百吨TNT当量爆炸在km量级范围内产生的电偶极子和磁偶极子辐射电场强度分别为kV/m和10 V/m量级。深空中地磁感应强度较弱,电子的角向运动相比初始方向运动是小量,因而磁偶极子的辐射强度远小于电偶极子的。     

Passage of radiation through a test hole

This paper discusses the passage of monoenergetic radiation through rectangular, cylindrical, and ring-shaped test holes. It is assumed that the sources are located at the far end and on the lateral surface of the test hole. Formulas are derived for calculating the radiation flux in test holes passing through both the shield and the core of the reactor. The results of the theory are compared with experiment.     

数字高斯脉冲成形算法仿真研究

高斯脉冲具有良好的时间、频率响应和较高的信噪比,探测器输出信号通常被滤波成形为高斯波形或类高斯波形。在高斯脉冲成形算法基础上,引入截止频率和品质因子,讨论成形参数对成形脉冲幅度、宽度的影响。通过与梯形脉冲成形算法对比,研究高斯脉冲成形算法的滤波效果以及对核信号幅度谱的作用。结果表明,在相同达峰时间条件下高斯脉冲成形算法具有更好的噪声抑制能力,同时可减小核信号幅度谱的半高宽;结合使用梯形脉冲成形算法可改善高斯脉冲成形算法在处理堆积脉冲中的不足,提高核信号通过率。     

The relative importance of surface phenomena in CTR first-wall designs

Plasma-wall interactions are modeled using physical sputtering theory. Sputtering yields are calculated for incoming D-T ions that have a monoenergetic or Maxwellian distribution in energy. The yield curves assuming the Maxwellian energy distribution are flatter than the monoenergetic curves. The consequences of sputtering considered here are surface composition and microtopography changes of the first-wall surface. For the iron-carbon system, the surface becomes enriched with carbon when deuterons are incident on the target. The number of cycles for crack initiation at the first-wall surface is linearly proportional to differences in sputtering yield of two adjacent areas. These effects are of first order and appear to be dominant in limiting the life of the first wall.