两维漂移室的结构和性能

在MIT型漂移室中加延迟线, 构成两维漂移室. 室内充P-9气体. 漂移室内电子平均漂移速度为3.34厘米/微秒. 室的平均空间分辨率为570微米. 对准直、穿过室的β射线, 输出脉冲幅度随β射线的入射位置有变化. X射线入射时, 在高电压区, 气体放大和X射线入射位置有关.     

Z-FFR聚变靶室物理状态分析与聚变X射线防护的初步设计

利用MULTI程序建立了大空间-时间尺度、Z-FFR聚变靶室气体氛围的辐射流体力学模型,研究了聚变X射线能量传输、气体氛围温度密度演化以及冲击波的形成和传播等物理过程,获得了第一壁表面辐射温度、冲击压力随时间的变化等重要参数。同时利用Geant4程序计算了静态X射线在第一壁耐烧蚀涂层中的能量沉积分布,研究了不同能量X射线在聚变靶室气氛中的衰减规律。综合动态和静态计算结果,完成了聚变X射线防护初步设计,确定第一壁入射X射线能量密度阈值约为0.2J/cm2,Ar气氛围压强为2000Pa。     

强吸收介质内部低Z材料结构的X射线显微成像研究

惯性约束核聚变靶室靶丸位置的原位无损检测是目前的研究热点和难点.针对此需求,建立了强吸收介质包裹的低Z材料X射线显微成像物理模型.通过计算机模拟和实验,较为系统地考察了光子能量、成像距离以及强吸收介质尺度等参量对成像质量的影响.结果表明,利用X射线相衬成像技术来实现惯性约束核聚变靶室靶丸的高分辨无损检测是可行的. 关键词： X射线显微 位相衬度 核聚变靶 无损检测     

激光等离子体光源软X射线反射率计

介绍了所研制的激光等离子体光源软X射线反射率计,该反射率计由激光等离子体光源、掠入射光栅单色仪、样品室、真空系统、样品台、光电探测系统和计算机控制系统组成,工作波段8～30 nm,测量样品的最大尺寸为130 mm×120 mm×120 mm(长×宽×高),可以利用这台反射率计对软X射线波段光栅、滤光片和多层膜反射镜等光学元件进行测量和评估。为检验反射率计的性能指标,利用该反射率计对本室研制的软X射线多层膜反射镜的反射率进行了测量,测量结果与理论计算结果符合较好,反射率测量重复性为±0.6%。     

强吸收介质内部低Z材料结构的X射线显微成像研究

惯性约束核聚变靶室靶丸位置的原位无损检测足目前的研究热点和难点.针对此需求,建立了强吸收介质包裹的低Z材料X射线显微成像物理模型.通过计算机模拟和实验,较为系统地考察了光子能量、成像距离以及强吸收介质尺度等参量对成像质量的影响.结果表明,利用X射线相衬成像技术来实现惯性约束核聚变靶室靶丸的高分辨无损检测是可行的.     

小单元漂移室用放射源模拟老化的实验研究

BESⅢ 漂移室(DC)模型用1.85X109 Bq 55Fe 5.9keV X射线放射源作加速老化实验研究.测量了阳极丝电流I和55Fe 5.9keV X射线全能光电峰位随累积电荷量Q的变化,由此得到累积相当BESⅢ DC 5年全天候运行的电荷量(0.07 C/cm)后,漂移室小单元的阳极电流降为初始值的87%;老化率为R=－0.19%/(mC/cm)     

采用微光摄象管的X射线电视

X射线电视是六十年代发展起来的一种新型工业电视.它的原理是通过电视摄象系统把X射线荧光屏上的微弱光图象尽量不失真地转换成电视讯号,在显象管屏幕上显示明亮的图象.这样做的主要优点是:(1)可以把过去暗室的X射线透视改成亮室观察,因而有利于改善工作条件及多人观察进行会诊,教学等.(2)采用了X线电视,对X线管球及荧光屏再采用遥控装置,那么就可以在隔室进行操作及观祭病人.这样就使从事X射线的工作人员避免直接接触有害的X射线.(3)由于X射线电视比一般透视的射线剂量低,可以降到人体的安全剂量以内,因此医务人员就可以在X射线配合下…     

气体探测器的最新应用

本文讨论了气体探测器在下述领域的最新应用:放射性痕量元素的二维图像;用X 射线衍射研究晶体结构;工业射线照相法;用核扩散的射线照相;契伦柯夫环探测器;流光管量热计;渡越辐射测量;用作电磁量热计的高密度显像室;用作探测契伦柯夫环的显像室。     

多丝正比室W–S阴极条两维读出方法研究

对一种简便的多丝室楔形一条形(W–S)阴极的感应电荷分布进行了详细的计算,制作了100×100mm²的丝室模型,用55FeX射线测量丝室的定位精度,并获得入射X射线的二维图像.     

杂质元素特征X射线对氢气放电源打靶新谱线的影响

 在氢气放电源打靶的实验中,测到了系列能量恒定不变的低能X射线新谱线,这些新谱线的能量分别为(1.70±0.10) keV, (2.25±0.07) keV,(2.56±0.08) keV,(3.25±0.10) keV和（3.62±0.11） keV,与Si,Ta,S,Cl,K和Ca等元素的特征X射线能量相近,但靶中所含的杂质或来自放电室的杂质元素可能会产生这些能量的X射线谱峰,证实新谱线是否由这些元素的特征X射线干扰所致显得尤为重要。分析了本实验系统中各种杂质的可能来源,论证了放电室端杂质对新谱线的影响,及靶材料中体杂质和面杂质对新谱线的影响;用X射线光电子能谱仪对靶做了表面分析。研究结果表明：杂质元素的特征X射线不会对氢气放电源打靶产生的新谱线有影响。这些新谱线的性质有待进一步的实验研究。     

基于X射线衍射仪的X光晶体本征参量的标定

X光晶体本征参量的实验标定是准确鉴定X光晶体种类和品质,研制各种类型晶体谱仪,X光线谱定量测量和高分辨X光单能成像的基础.基于X射线衍射仪,通过制作平面晶体样品架,采取控制X射线管电源、滤波片选取和厚度控制等措施,极大地抑制了Cu-KJ3及韧致辐射,使X射线管光源Cu-Kα单能化,提出了用滤片作为光源单能化的判据.对X光线谱测量中常用的X光分光晶体季戊四醇[PET(002)]的晶格常量2d和Cu-Ka能点的积分衍射效率R.进行了标定方法研究,其标定值分别为(0.87425±0.00042)nm和(1.759±0.024)×10-4 Rad.基于X射线衍射仪的X光晶体本征参量的精密实验标定方法既快速高效,且十分方便和灵活.通过更换衍射仪的X射线管靶材,采取类似方法,可以标定其它能点的晶体积分衍射效率,可为X光晶体的本征参量库提供更多的标定数据.     

强脉冲X射线辐照Si-SiO2界面对C-V 和I-V特性曲线的影响

 利用强脉冲X射线对Si-SiO₂界面进行了辐照，测量了C-V曲线和I-V曲线。实验发现，经过强脉冲X射线对Si-SiO₂界面进行的辐照，使C-V曲线产生了正向漂移，这一点与低剂量率辐射结果不同；辐射后，感生I-V曲线产生畸变；特别地，从I-V曲线上还反映出强脉冲X射线辐照的总剂量效应造成电特性 参数明显退化，最后甚至失效。讨论了强脉冲X射线辐照对Si-SiO₂界面产生损伤的机理，并对实验结果进行了解释。     

X‐ray spectra by means of Monte Carlo simulations for imaging applications

X‐ray tubes have a broad range of applications worldwide, including several techniques for atomic physics, like X‐ray fluorescence, as well as for medical imaging, like computed tomography. The performances of X‐ray imaging detectors have shown to be significantly sensitive to the incident beam spectrum. Therefore, an accurate knowledge of the X‐ray beam becomes necessary for the emission source characterization and the whole imaging process comprehension. Direct measurements and suitable Monte Carlo simulations may be used to establish the X‐ray spectra. Dedicated Monte Carlo simulation routines, based on the PENELOPE code, have been developed to determine the Bremsstrahlung X‐ray spectra generated by conventional X‐ray tubes. The simulated spectra have been validated by comparison with the corresponding experimental data showing an overall good agreement. The incorporation of a suitably designed virtual grid allowed to assess the angular distribution of Bremsstrahlung yield, showing a remarkable anisotropy. In addition, a dedicated program has been developed for virtual imaging, which enables to perform suitable X‐ray absorption contrast images. Also, the developed program includes a user‐friendly graphic interface to allow the upload of required input parameters, which include setup arrangement, beam characteristics, sample properties and image simulation parameters (spatial resolution, tracks per run, etc.). The software includes dedicated subroutines which handle the physical process from X‐ray generation up to detector signal acquisition. The aim of the developed program is to perform virtual imaging by means of absorption contrast and using conventional X‐ray sources, which may be a useful tool for the study the X‐ray imaging techniques in several research fields as well as for educational purposes. The performed comparisons with experimental data have shown good agreement. The obtained results for X‐ray imaging may constitute useful information for the comprehension and improvement of X‐ray image quality, like absorption contrast optimization, detail visualization, definition and detectability. Copyright © 2010 John Wiley & Sons, Ltd.     

Hard X‐ray microbeam lithography using a Fresnel zone plate with a long focal length

Focused hard X‐ray microbeams for use in X‐ray nanolithography have been investigated. A 7.5 keV X‐ray beam generated at an undulator was focused to about 3 µm using a Fresnel zone plate fabricated on silicon. The focused X‐ray beam retains a high degree of collimation owing to the long focal length of the zone plate, which greatly facilitates hard X‐ray nanoscale lithography. The focused X‐ray microbeam was successfully utilized to fabricate patterns with features as small as 100 nm on a photoresist.     

X‐ray tube spectral measurement method for quantitative analysis of X‐ray fluorescence analysis

Lα and Lβ X‐ray fluorescence spectra of a lead metallic sheet were measured using an energy dispersive X‐ray spectrometer by changing the X‐ray tube voltage and the material of the primary filter. The Lα to Lβ intensity ratio changed from Lα: Lβ = 3: 1 at 15 kV to Lα: Lβ = 1: 1 at 50 kV depending on the X‐ray tube voltage and the filter. The scattered X‐ray spectra of an acrylic slab instead of the sample in the sample holder were measured by changing the applied voltage and the material of the primary filter. The calculated values of the Pb Lα/Lβ intensity ratio of the metallic sheet using the Shiraiwa–Fujino formula by inserting the scattered X‐ray spectra of an acrylic plate as incident X‐ray spectra and the fundamental parameters taken from the Elam database were in good agreement with the experimental ones. We conclude that we can obtain an incident X‐ray spectrum approximately by measuring the scattered X‐ray spectrum without measuring the direct incident beam. Copyright © 2010 John Wiley & Sons, Ltd.     

双狭缝透射光栅软X光时空分辨谱仪

 利用双狭缝、透射光栅配亚仟X光条纹相机做了具有一维空间、时间和能谱分辨的三维软X光测量仪器(双狭缝透射光栅软X光时空分辨谱仪), 并成功地获得了金盘靶的N带X光(中心波长1.7nm)时空分辨图象 。该仪器空间分辨可达23μm, 时间分辨可达003ns, 能谱分辨(当源大小为100～300μm时对波长1.7nm的X光)可达0.4～ 0.7nm, 只需稍加改动, 即可用于其它波段的X光测量。     

光学元件表面粗糙度对第三代同步辐射光源空间相干性的影响

以单丝的同轴全息干涉花样为判别标准,通过计算机数值模拟,研究了Ｂｅ窗的表面粗糙度对硬Ｘ射线相干特性的影响。提出了Ｘ射线在粗糙表面反射的一个简单模型,以此为基础模拟研究了反射镜表面粗糙度的对硬Ｘ射线及软Ｘ射线空间相干特性的影响,模拟结果与实验结果相符。     

1.06μm激光等离子体X光转换实验研究

Ｘ光转换是激光—等离子体相互作用中的一个重要研究课题。文中介绍了在“神光”装置上利用亚千Ｘ光能谱仪测量Ｘ光能谱、辐射温度与Ｘ光转换效率；并给出了转换Ｘ光总量、辐射温度与激光能量、脉冲宽度及腔面积的定标关系。     

Multivariate analysis of hyperspectral hard X‐ray images

This article describes methods to analyse and process hyperspectral hard X‐ray imaging data. We focus on the use of multivariate techniques that exploit the spectral information to make informed decisions on the material content within each pixel of an X‐ray image. These analysis methods have the ability to auto‐segment data without prior knowledge of the sample composition or structure, and are particularly useful for studying completely unknown, diluted or complex specimens. We demonstrate the methods on a variety of hard X‐ray images including X‐ray fluorescence and absorption data recorded using a hard X‐ray imaging spectrometer. The multivariate methods described are very powerful with the ability to segment, distinguish and, in some cases, identify different materials within a single X‐ray image. Potential uses of hyperspectral X‐ray imaging are discussed varying from materials science to industrial or security applications. Copyright © 2013 John Wiley & Sons, Ltd.     

X‐ray spectromicroscopy in soil and environmental sciences

X‐ray microscopy is capable of imaging particles in the nanometer size range directly with sub‐micrometer spatial resolution and can be combined with high spectral resolution for spectromicroscopy studies. Two types of microscopes are common in X‐ray microscopy: the transmission X‐ray microscope and the scanning transmission X‐ray microscope; their set‐ups are explained in this paper. While the former takes high‐resolution images from an object with exposure times of seconds or faster, the latter is very well suited as an analytical instrument for spectromicroscopy. The morphology of clusters or particles from soil and sediment samples has been visualized using a transmission X‐ray microscope. Images are shown from a cryo‐tomography experiment based on X‐ray microscopy images to obtain information about the three‐dimensional structure of clusters of humic substances. The analysis of a stack of images taken with a scanning transmission X‐ray microscope to combine morphology and chemistry within a soil sample is shown. X‐ray fluorescence is a method ideally applicable to the study of elemental distributions and binding states of elements even on a trace level using X‐ray energies above 1 keV.