New method for measuring beam profiles using a parametric X-ray pinhole camera

We propose a new method for measuring electron beam profiles using parametric X-ray radiation. In this method, a pinhole is placed between the source of parametric X-ray radiation and a two-dimensional X-ray detector, and the beam profile can be reconstructed on the detector, i.e., based on the principle of a pinhole camera. The profiles are in good agreement with the results obtained using a standard method with optical transition radiation. This method may prove useful to measure profiles of electron beams with short bunch lengths in recent advanced linear accelerators.     

实时测量的X射线针孔相机信号强度估算

 对用X射线CCD作测量设备的在线针孔相机信号强度进行了估计。利用激光原型装置柱腔能谱曲线、PI-SX1300型号X射线CCD的量子效率曲线分别对在CCD加Be滤片和加不同材料的平面镜两种情况下的针孔相机成像获得的Ｘ射线信号在CCD上的信号强度计数进行了估算,结果表明：厚度不大于200 μm的Be滤片只能将信号强度的计数降低一个量级;3°入射的金平面镜,5°入射的镍、碳平面镜和硅平面镜虽然也可将信号强度计数降低一个量级,但这两种衰减方法得到的强度计数超过了CCD的饱和计数值。计算了不同厚度的Be滤片结合平面镜的针孔相机对信号强度计数的衰减情况,结果表明：Be的厚度在20～40 μm时,平面镜选择3°入射的金平面镜或者5°入射的镍平面镜,两者结合可以较好地衰减信号。     

实时测量的X射线针孔相机信号强度估算

对用X射线CCD作测量设备的在线针孔相机信号强度进行了估计。利用激光原型装置柱腔能谱曲线、PI-SX1300型号X射线CCD的量子效率曲线分别对在CCD加Be滤片和加不同材料的平面镜两种情况下的针孔相机成像获得的Ｘ射线信号在CCD上的信号强度计数进行了估算,结果表明：厚度不大于200 μm的Be滤片只能将信号强度的计数降低一个量级;3°入射的金平面镜,5°入射的镍、碳平面镜和硅平面镜虽然也可将信号强度计数降低一个量级,但这两种衰减方法得到的强度计数超过了CCD的饱和计数值。计算了不同厚度的Be滤片结合平面镜的针孔相机对信号强度计数的衰减情况,结果表明：Be的厚度在20～40 μm时,平面镜选择3°入射的金平面镜或者5°入射的镍平面镜,两者结合可以较好地衰减信号。     

The beam-based calibration of an X-ray pinhole camera at SSRF

A pinhole camera for imaging X-ray synchrotron radiation from a dipole magnet is now in operation at the Shanghai Synchrotron Radiation Facility (SSRF) storage ring. The electron beam size is derived by unfolding the radiation image and the point spread function (PSF) with deconvolution techniques. The performance of the pinhole is determined by the accuracy of the PSF measurement. This article will focus on a beam-based calibration scheme to measure the PSF system by varying the beam images with different quadrupole settings and fitting them with the corresponding theoretical beam sizes. Applying this method at SSRF, the PSF value of the pinhole is revised from 37 to 44 μm. The deviation in beam size between the theoretical value and the measured value is minimized to 4% after calibration. This optimization allows us to observe the horizontal disturbance due to injection down to as small as 0.5 μm.     

HL-2A中子相机屏蔽系统模拟

利用蒙特卡罗模拟程序,建立了HL-2A中子相机蒙特卡罗粒子输运(MCNP)物理模型,对D-D聚变中子和γ射线的屏蔽进行了模拟计算。对石蜡碳酸锂混合物、聚乙烯、铅和316L不锈钢4种常用中子慢化吸,收剂组成的屏蔽层材料的屏蔽效果进行了对比。计算结果表明,石蜡碳酸锂混合物和铅组合是中子相机的最佳屏蔽层材料,其中石蜡碳酸锂混合物用于慢化吸收中子,铅用于屏蔽中子和γ射线。此外,利用MCNP模拟计算得到了屏蔽中子和γ射线所需的屏蔽厚度,以及准直管的中子散射率。     

Results of spectral monitoring of environmental gamma background in a fault zone of the Western Caucasus for seismological application

Results of continuous spectral monitoring of indoor gamma background are reported for seismological application in one fault zone of the Western Caucasus. Background count rates were recorded every 5 min since 2004. Two detectors (a scintillation crystal CsI(Tl), 200 mm × 150 mm in a low background metal screen and a NaI(Tl) detector, 90 mm × 90 mm outside of the screen) were used. Various intervals of energy of gamma rays, for example, (2.50–3.40) MeV, (1.70–2.00) MeV, (1.35–1.55) MeV and others were analyzed. Averages for all measurements as well as seasonal and hourly changes of count rate of detectors were obtained. As an example, for the interval (1.70–2.00) MeV a minimal monthly count rate of detector CsI(Tl) was observed in June, and the maximal monthly count rate of detector NaI(Tl) was observed in July. Factors of correlation between different intervals of energy of gamma rays were also investigated. Strong changes of annual, monthly and daily factors were obtained.In each daily curve of all intervals of energy of gamma rays, the first Fourier harmonic was calculated. The deviations from 3σ (“splash”), which are upward or downward from the first harmonic, were compared with the seismological data. It was possible to correlate the low background dates of “splashes” with the dates of regional earthquakes through 9 ± 1 days.Change of ratio of count rate in different intervals of energy of gamma rays can be used to study processes of preparation of earthquakes.The factor of correlations between intervals (2.50–3.40) MeV and (1.70–2.00) MeV increased to almost 1.00 close to earthquakes. This effect was obtained in low background screen.Connection of the gamma data with the meteorological data was not obtained.     

Development of a panorama coded-aperture gamma camera for radiation detection

For radiation detection, the imaging system should have a large field of view (FOV) and high detection efficiency because it has to be used in a radiation environment where the quantity and direction of radioactive sources are unknown. A panorama coded-aperture gamma camera optimized for use in complex nuclear environment has been developed and evaluated with an angular resolution of 3.5°. Typical gamma cameras have the limited field of view ranging from 10° to 60° in both horizontal and vertical direction. The system presented in this paper extends the field of view to 360° in the horizontal direction and 60° in the vertical direction. The partial encoding of coded aperture imaging is mitigated by convolving the data of diverse adjacent modules with a partial transmission function. The experimental feasibility of measuring multiple sources in the 360° horizontal field of view was demonstrated with a panoramic image. The results showed that the system could clearly identify the direction of multiple radiation sources in an unknown extended radiation environment. The system can help to simplify the clean up and decommissioning of nuclear sites.     

Optimization of a pinhole camera for neutron diffraction of a thermonuclear laser plasma

The nonstationary transport equation of DD and DT neutrons in a polyethylene wall with a cylindrical opening is solved by the Monte Carlo method. It is shown that the proposed pinhole camera lowers the requirements for brightness of a neutron source by two orders of magnitude in comparison to the existing analogs. Analytical estimates of the resolving power of the pinhole camera are given, and ways to improve it are analyzed. The region of permissible values of the parameters of the pinhole camera is constructed. Contour lines of the images of neutron point sources as functions of their number and position in the thermonuclear target are calculated. Zh. Tekh. Fiz. 68, 104–109 (September 1998)     

CCD摄像机技术的发展趋势及应用前景

本文系统地介绍了国内外ＣＣＤ 技术的发展和未来ＣＣＤ 市场的需求,并给出了统计参考数据。讨论了ＣＣＤ 传感器需改进的几个方面和ＣＣＤ 摄像机技术性能的优化指标。文中详细地阐述了ＣＣＤ 应用的多种领域及其发展的趋势。对ＣＣＤ 摄像机技术性能的改进如Ｈｙｐｅｒ Ｄ、ＤＳＰ、ＰＳ 等作了具体介绍。     

针孔相机全场X射线荧光成像的模拟研究

为解决全场X射线荧光(XRF)成像中针孔形状和尺寸的选取问题,采用Geant4软件,模拟了6种不同类型针孔和4种不同的针孔孔径,分析了这些参数对点扩散函数和调制传递函数的影响;模拟了不同能量X射线荧光平面源的成像过程,并用均值滤波和Richardson迭代法对图像进行处理,分析了图像处理的效果。模拟结果表明：对于能量小于20 keV的荧光X射线,双锥孔结合直孔模型的点扩散函数尖锐性和等晕性更好,调制传递函数的截止频率更大,空间分辨更好,更适合做全场XRF成像的针孔;均值滤波结合Richardson迭代法的图像处理算法对全场XRF图像处理的效果较好。     

Investigation of high resolution compact gamma camera module based on a continuous scintillation crystal using a novel charge division readout method

The objective of this study is to investigate a high performance and lower cost compact gammacamera module for a multi-head small animal SPECT system.A compact camera module was developed usinga thin Lutetium Oxyorthosilicate(LSO)scintillation crystal slice coupled to a Hamamatsu H8500 positionsensitive photomultiplier tube(PSPMT).A two-stage charge division readout board based on a novel subtractive resistive readout with a truncated center-of-gravity(TCOG)positioning method was developed for the camera.The performance of the camera was evaluated using a flood 99mTc source with a four-quadrant bar-mask phantom.The preliminary experimental results show that the image shrinkage problem associated with the conventional resistive readout can be effectively overcome by the novel subtractive resistive readout with an appropriate fraction subtraction factor.The response output area(ROA)of the camera shown in the flood image was improved up to 34%,and an intrinsic spatial resolution better than 2 mm of detector was achieved.In conclusion,the utilization of a continuous scintillation crystal and a flat-panel PSPMT equipped with a novel subtractive resistive readout is a feasible approach for developing a high performance and lower cost compact gamma camera.     

Investigation of high resolution compact gamma camera module based on a continuous scintillation crystal using a novel charge division readout method

The objective of this study is to investigate a high performance and lower cost compact gamma camera module for a multi-head small animal SPECT system. A compact camera module was developed using a thin Lutetium Oxyorthosilicate （LSO） scintillation crystal slice coupled to a Hamamatsu H8500 position sensitive photomultiplier tube （PSPMT）. A two-stage charge division readout board based on a novel subtractive resistive readout with a truncated center-of-gravity （TCOG） positioning method was developed for the camera. The performance of the camera was evaluated using a flood 99roTe source with a four-quadrant bar-mask phantom. The preliminary experimental results show that the image shrinkage problem associated with the conventional resistive readout can be effectively overcome by the novel subtractive resistive readout with an appropriate fraction subtraction factor. The response output area （ROA） of the camera shown in the flood image was improved up to 34%, and an intrinsic spatial resolution better than 2 mm of detector was achieved. In conclusion, the utilization of a continuous scintillation crystal and a flat-panel PSPMT equipped with a novel subtractive resistive readout is a feasible approach for developing a high performance and lower cost compact gamma camera.     

CCD摄像技术在大气光学传输特性监测研究上的应用

介绍以CCD摄像机为光学图像传感系统 ,通过定量测量景物 (目标 /背景 )亮度的大气传输衰减 ,来测定白天大气的光学传输特性的一种光学图像测量方法。介绍了系统的测量原理、方法、系统基本构成、基本技术指标要求和所采用的技术方案 ,给出该系统与激光雷达进行对比试验的结果。实验结果表明 ,经过一定的对比和标定 ,该系统可直接用来测量、监测白天大气的消光系数或水平气象能见度。     

大气环境对空间CCD相机成像的影响

分析了大气环境对空间CCD相机在轨成像的影响,应用计算软件对大气环境影响空间相机成像的传递函数进行了初步的计算。     

摄像型等厚干涉实验仪器的研究

介绍了“摄像型等厚干涉实验仪”的构造及等厚干涉实验新的测量方法。     

High‐resolution angular beam stability monitoring at a nanofocusing beamline

Two semi‐transparent imaging beam‐position monitors developed at the ESRF have been installed at the micro‐analysis beamline ID22 for monitoring the angular stability of the X‐ray beam. This system allows low‐frequency (10 Hz) angular beam stability measurements at a submicroradian range. It is demonstrated that the incoming macro‐beam angular fluctuations are one of the major sources of focal spot instabilities downstream of the Kirkpatrick–Baez mirrors. It is also shown that scanning the energy by rotating the so‐called fixed‐exit monochromator induces some unexpected angular beam shifts that are, to a large extent, deterministic.     

Developing a gamma ray fluid densitometer in petroleum products monitoring applications using Artificial Neural Network

In gamma-ray densitometry the determination of density is performed by the use of calibration tables. Calibration and consequently the accuracy of the system can be influenced when a number of important system parameters such as pipe diameter, source to detector distance and so on are changed from one case to another. In this work an Artificial Neural Network model was proposed for developing a previously designed and constructed gamma ray densitometer in prediction of fluid density of different petroleum products. The required data for training and testing the ANN model has been obtained based on simulations using MCNP4C Monte Carlo code. Simulations for 4-inch polyethylene pipe had been validated with the experimental data previously. The Mean Relative Error (MRE) from ANN modeling was less than 0.5%. Results show that proposed ANN model represents a good estimation of the density in petroleum products monitoring application and can be used as a reliable and accurate tool.     

微光ICCD电视摄像技术的发展与性能评价

利用微光像增强器的图像增强功能,将微光像增强管耦合到电荷耦合器件(CCD)上即构成微光图像增强CCD(简称ICCD)。它具有两个重要的特性:一是通过选择适当的像管输入窗及光电阴极,使ICCD光谱响应范围由可见光扩展到X射线、紫外、近红外区域,从而使该器件能适用于各种用途;二是使ICCD的灵敏度达到10-4lx以下,实现了ICCD摄像器件在黎明或黄昏的照度下(102lx)在1/4月光下(10-2lx)、在星光下(10-4lx)都能有效的工作。微光ICCD电视摄像系统可应用在天文、医疗、火控、制导、飞机紫外预警等方面。重点阐述了微光ICCD电视摄像技术的发展与性能评价。     

Design and fabrication of a high temperature X-ray powder diffraction camera

A high temperature X-ray powder diffraction camera has been designed and fabricated with indigenous material. The camera design is similar to the Unicam model but overcomes some inconvenient features of the latter. The camera incorporates a miniheater which is inexpensive and easily replaceable. The camera enables determination of lattice parameters with an accuracy of ±0.0002 Å up to 800°C.