软X射线探测器

西安光机所自1984年开始,共研制了不同型的五台软X射线条纹相机;1987年开始,研制了软X光分幅相机。这些仪器,已在激光核聚变研究、激光等离子体诊断、核试验及爆轰物理研究等领域,作为有效的测试工具。本文介绍了我们的有关研究工作和X线条纹相机、分幅相机的主要性能。     

New Neutron, Gamma and X-Ray Detectors

New detectors intended to record absorbed doses of neutron, gamma and X-radiation in a range of 0–1500 Mrad are described. One of these detectors is based on dibutylphthalate (DP), another is based on epoxy resin, and a 5-40 detector is a mixture of dibutylphthalate and epoxy resin. Experimental methods of detector calibration and for the interpretation of measured absorbed doses are given for these detectors. All three detectors cover a measured dose range of 0–30000 Mrad. The measurement accuracy is ±10% and, in fact, does not depend on the radiation dose rate within 20–2000 rad/s at temperatures of 20–80°C. The detectors can be applied in the atomic industry, radiation biotechnology, medicine (for object radicidation), the food industry for radiation handling of foodstuffs, radiation processing of paper (for example, mail radiation processing), etc.     

A Ring Neutron Detector for a Time-of-flight Diffractometer Based on Linear Scintillation Detectors with Silicon Photomultipliers

A ring neutron detector has been developed for a time-of-flight diffractometer based on linear scintillation detectors. Light is transported over an organic glass light guide with a diffuse reflector. This scheme makes it possible to collect more photons than are collected in detectors based on wavelength-shifting fibers and to use avalanche photodiodes (SiPMs) instead of photomultiplier tubes. Testing confirmed that these detectors could be used as an alternative for widely used proportional neutron counters filled with ³He.     

A Dosimeter for On-line Dose Rate Monitoring Based on a Natural Diamond Detector

The structure and principle of operation of a dosimeter for on-line dose rate monitoring (DOM) are considered. The DOM provides real-time measurements of the absorbed -ray and electron dose rates, monitors relative distributions of radiation fields in radiotherapy facilities, and controls the radiation characteristics of radiotherapeutic equipment during its adjustment, certification, and service. The dosimeter can measure the dose absorbed in a certain period of time. Compared to conventional dosimeters based on air ionization chambers and silicon semiconductor detectors, the DOM has a number of advantages: dose-rate measurement linearity, energy independence of radiation detection in the range of 0.8–20 MeV for -rays and 8–20 MeV for electrons, high sensitivity compared to air ionization chambers, high radiation and thermal stability, and the small size of the device. The detecting element of the dosimeter is manufactured from a tissue equivalent to a biological material. The operating ranges of dose rate measurements are 10^–3–10 Gy/min and 10^–2–10² Gy/min. The DOM measurement error is <2%. Radiation therapy is the dosimeter field of application.     

A Beta Spectrometer Based on Silicon Detectors

The characteristics of a beta spectrometer that consists of a total-absorption Si(Li) detector and a drift Si detector are presented. Using this spectrometer, it is possible to efficiently separate β radiation of nuclei from concomitant X and γ rays. The method is based on coincidences between signals from the thick and thin detectors. The spectrometer can be used to precisely measure the shape of the β spectra of various radioactive nuclei, in particular, of the ¹⁴⁴Pr nucleus, which is the most promising antineutrino source for searching for neutrino oscillations into a sterile state.     

Gas-Discharge Detectors for Monitoring the Total Neutron Yield in the International Thermonuclear Experimental Reactor

The design of two detector units made integral with their communications links is described. The detector unit composed of a KHT23-1 fission chamber and an assembly of CHM67 neutron counters is used to detect slow neutrons, while the detector unit based on a KHT23-8 threshold fission chamber is intended for fast neutrons. The parameters of these detector units along with their communications links are presented.     

天然金刚石刀具技术的发展概况

回顾了天然金刚石刀具及其加工技术的发展历程 ,介绍了天然金刚石刀具最新加工技术 ,探讨了金刚石刀具技术的发展方向。     

串珠绳结构对金刚石串珠绳固有频率影响的仿真研究

利用有限元建立了金刚石串珠绳的简化模型,分析了金刚石串珠绳的固有频率,并通过实验,对所建立的串珠绳有限元进行了验证。在此基础上仿真分析了串珠绳结构对金刚石串珠绳固有频率的影响。实验结果表明,所建立的串珠绳有限元模型与实验结果有很好的吻合。增加串珠绳的长度,串珠绳的固有频率会随之减小;而减少每米串珠的个数,固有频率会随之增加;随着串珠外径的增加,串珠绳的固有频率会有所减小;另外,随着串珠绳内部钢丝绳变粗,其固有频率也会略有降低。     

Fast cryofixation technique for X-ray microanalysis

The proposed cryofixation technique uses a tubule-shaped needle chilled in liquid propane for simultaneous excision and freezing of a tissue specimen. Due to this simultaneity, ionic shifts created by traumatic influences are avoided even in the outermost cells of the specimen. Moreover, it is shown here that stopping the blood flow for more than about 10 s results in notable ionic shifts between cells and extracellular space in rat heart and liver. Such preparative ischaemic injury is minimized by the Fast Cryofixation Technique because it can be easily performed on organs within the circulatory system, whilst the heart of the animal is still beating. Intracellular concentrations of the monovalent ions in rat heart and liver, obtained by this method, tally well with recent results from different independent techniques reported in the literature. As demonstrated by cross-sectioning and freeze-fracturing, the structural preservation of the freezing technique is sufficient for X-ray microanalytical work.     

Simulation Research of Influence on Diamond Wiresaw Natural Frequency by Structure

利用有限元建立了金刚石串珠绳的简化模型,分析了金刚石串珠绳的固有频率,并通过实验,对所建立的串珠绳有限元进行了验证.在此基础上仿真分析了串珠绳结构对金刚石串珠绳固有频率的影响.实验结果表明,所建立的串珠绳有限元模型与实验结果有很好的吻合.增加串珠绳的长度,串珠绳的固有频率会随之减小;而减少每米串珠的个数,固有频率会随之增加;随着串珠外径的增加,串珠绳的固有频率会有所减小;另外,随着串珠绳内部钢丝绳变粗,其固有频率也会略有降低.     

基于X-R正交分解原理的新型金属探测仪的设计

介绍了金属探测的理论基础,设计使用了3片直接数字合成(DDS)芯片AD9832.利用其精确的数字调节频率和相位的功能,通过ATMEGAl28控制,产生2路同相位的正弦波信号和1路与之正交的正弦波信号.运用X-R正交分解原理,提出对铁磁性和非铁磁性金属的探测方法.它的灵敏度高、稳定性好,能够得到稳定的控制效果.可用于采煤、采石、食品加工等行业,大大提高了生产率并显著改善了产品的质量.     

High-Intensity Neutron Fields for Calibrating the Detectors of a Standard Control System of High-Power Nuclear Reactors

The characteristics of ten high-intensity modelling neutron fields in research nuclear reactors with various ratios of the contributions of thermal and epithermal neutrons have been measured in order to be used for calibrating the internal detectors of the standard control system of high-power nuclear reactors. The neutron fields in the F-1, Gidra, and KVANT reactors are certified as working standards of the first and second kind.     

单层钎焊金刚石砂轮表面磨粒全场快速测量

为了快速获取单层钎焊金刚石砂轮表面全场磨粒的二维分布信息,提出了一种基于线阵相机的快速测量方法。对检测系统的原理、清晰无运动失真图像的获取、图像处理关键算法等进行研究。首先给出了检测系统的硬件构成与检测系统的工作原理;使用8方向模板的Sobel算子和标准件,完成相机对焦和运动失真图像矫正,然后对预处理的图像采用改进的阈值分割法Otsu算子对图像进行分割,最后实现了磨粒坐标及等效面积等二维特征量的提取。对磨粒有序排布的单层钎焊砂轮（粒度号35/40）进行测量实验,实验结果表明,系统从拍摄砂轮全场磨粒图像到获取磨粒坐标及等效面积所用的时间为77.4 s,可满足对单层钎焊砂轮的全场磨粒快速测量的要求。     

High-Intensity Neutron Fields at the Center of the Metallic Core of Fast Reactors as the Primary Standard Neutron Fields

It is proposed to use high-intensity neutron fields with an average neutron energy of 0.7–1.5 MeV at the center of the metallic core of fast reactors as the primary standard neutron fields along with the known standard fields of fission neutrons with average energies of 1.93 and 2.13 MeV, respectively, from ²³⁵U and ²⁵²Cf nuclei, which are used in the world practice of taking neutron measurements. It is also proposed to create standard fields of nuclear fission neutrons with an average energy of 2 MeV by the bombardment of ²³⁵U converters with a beam of fast monoenergetic neutrons with energies of 2.5 and 14 MeV and 50-MeV protons.     

基于DMT模型的金刚石表面纳米摩擦学研究

基于DMT接触模型,在理论上计算金刚石表面纳米摩擦的摩擦力和摩擦因数;采用原子力显微镜,以金刚石探针和片状金刚石试件作为摩擦副,在大气环境下分别研究机械抛光和聚焦离子束（FIB）刻蚀的金刚石试件的摩擦学特性,并比较实验结果和DMT接触模型计算结果。结果表明：金刚石试件的摩擦因数均随着载荷的增加而减小,这与以往对金刚石微观摩擦的研究结果相符合;DMT接触模型计算结果与机械抛光表面试验结果吻合较好,而略高于FIB刻蚀表面试验结果,验证了DMT模型在金刚石纳米摩擦研究中的适用性。通过表面粗糙度和碳原子化学状态分析,得出粗糙表面对探针滑动的阻碍作用和FIB刻蚀过程中生产的非晶碳的减摩作用是DMT模型应用于上述2种加工表面产生差异的原因。     

基于CETOL的中子屏蔽结构公差分析

基于CATIA下对托卡马克装置真空室中子屏蔽块的三维模型进行了公差分析。在三维实体模型的基础上,对要分析的部件进行了分割和模型简化。利用公差分析软件CETOL,根据中子屏蔽块的装配性能要求,首先确定基准,然后添加尺寸公差、几何公差等精度要求,进行装配约束,建立了公差分析模型。通过敏感度和贡献度数值查找影响公差分析结果的关键尺寸,对不合理的精度设计进行了修改,在保证装配精度的前提下,适当提高关键尺寸的精度可以避免干涉并显著提高装配精度,而适当降低非关键尺寸的公差可降低加工成本。     

金刚石印压微孔成形装置开发与试验研究

针对微孔冲压成形在工业领域的重要应用,开发了一种金刚石印压微孔装置,能够实现金属薄片上单侧微孔的成形加工。基于该装置,采用金刚石锥形压头及其刀尖钝圆对载有玻璃基底的铜片进行印压成孔试验,检测表明:该装置能够实现金属薄片上微孔的成形加工,装置采用多传感器原位检测技术对铜片底部成孔时刻进行准确判断,并可记录铜片底部所受压力的变化规律和金属塑性流动情况,满足了金属薄片上单侧微孔成形加工的需求,具有结构简单、成本较低等优点。     

基于正交实验方法评定金刚石工具耐磨性研究

本实验研究的目的是通过对不同的加工参数对热压成型的金刚石刀具磨损量影响的分析,进而确定较理想的加工参数,实现高效率的加工。实验采用三维雕刻机铣削的工作原理,通过正交实验的设计方法,并制定不同的加工参数,刀具的磨损量应用高精密电子天平测得,刀具表面磨损形态应用体式显微镜观测。实验数据表明,对金刚石刀具磨损量影响的主要参数是切削深度,其次是进给速度,最后是主轴转速。刀具底面磨损比侧面严重,底面磨损主要以脱落为主,侧面主要以冲击破碎为主。     

Radiation Hardness of a Fast Neutron Scintillation Spectrometer with a Stilbene Crystal

Neutron detectors with organic oscillators such as stilbene crystals are suggested for use in measuring the characteristics of neutron radiation in the International Thermonuclear Experimental Reactor (ITER). These detectors will be used as neutron-flux monitors in a multichannel neutron collimator for obtaining the spatial characteristics of a plasma source of thermonuclear neutrons with a 1-ms temporal resolution. In addition, operation in the spectrometric mode will ensure the measurement of the thermonuclear-neutron energy spectrum, which yields data on the fusion-plasma temperature and the ratio of the deuterium and tritium concentrations. During the operation of the facility, the detectors will be exposed to irradiation with a large fluence of fast neutrons. The first results obtained in studies of the characteristics of a stilbene crystal irradiated by fast neutrons with a fluence of up to 10¹⁴ neutrons/cm² are presented.     

基于快速伺服刀架技术的菲涅尔微结构金刚石超精密加工及其控制技术

微结构功能表面的金刚石超精密加工技术是近年来国外兴起的一项新技术,国内在这一研究领域处于起步阶段。并且由于受加工设备所限,使得该技术在国内的开展显得异常艰难,为了克服这一困难,自行设计带有快速伺服刀架(Fasttoolservo,FTS)的超精密加工机床,提出按照自适应指数趋近律来设计滑动模态控制律,并将滑膜变结构控制策略引入FTS的控制中,同时,将FTS的PID控制策略和滑膜变结构控制策略进行试验对比,试验结果显示,在滑模变结构控制策略下,FTS的响应时间与PID控制相近,但滑模变结构控制算法下几乎无超调,稳态精度高,正弦跟踪控制效果优于常规PID控制算法;最后,根据滑膜变结构控制策略对菲涅尔微结构表面进行金刚石超精密车削加工试验,成功地加工出半径5mm,浮雕深度10μm,表面粗糙度约35nm的菲涅尔微结构。