用于原位小角X射线测量的可变温液体样品槽的研制

根据小角X射线散射(Small angle X-ray scattering,SAXS)技术特点和北京同步辐射装置1W2A小角站光源参数,设计了一款用于液体样品原位变温测试的样品槽。该样品槽采用双面变温方式使样品温度整体均匀,涵盖5-95oC较宽温度范围;待测溶液厚度不仅可根据溶液组分进行调节,且在变温过程中保持恒定,利于提高数据质量。通过设计,实现了待测溶液和背底溶液同时变温和交替测量,节省了宝贵的同步辐射机时。ANSYS热分析表明,设备结构设计合理,样品处温度精度通过校正能得到进一步提高。通过检测聚酰胺-胺(Polyamidoamine,PAMAM)树形大分子结构随温度的变化,表明该样品槽满足液体原位变温SAXS测试要求。     

450keV锥束CT系统的散射校正研究

在450keV锥束工业CT成像系统中,对投影数据进行适当的散射校正是一步重要的数据校正.结合国内外散射校正方法研究的现状,对一种用散射校正板来进行散射校正方法的原理和实现进行了深入的研究.实验结果表明,这种校正方法能够对450KeV锥束CT成像系统进行有效地散射校正.     

中子小角散射实验及原始数据的处理

中子小角散射技术是研究纳米尺度范围材料结构的有力工具。中子小角散射实验测量和原始数据的处理方法相对较复杂。为了获得样品的绝对中子小角散射强度数据,通常需要进行入射中子束强度、散射强度、样品的透射率、实验本底以及空样品盒的散射强度和透射率等多项实验测量。若要获取较宽散射矢量范围的实验数据,还要改变实验仪器设置,对同一样品进行几次测量。而对所测数据也需要进行多项处理,才可获得便于分析的小角散射强度曲线。本文简单介绍实验原理和测量方法,重点讨论原始数据的处理方法,其中详细讨论了各向同性散射数据的平均以及合并方法。     

同步辐射小角X射线散射数据批量预处理程序PreSAXS1.0

随着同步辐射小角X射线散射(Small-angle Scattering of X-ray,SAXS)技术的快速发展,很大程度提高了散射实验的速度。对于高通量散射实验采集到的海量原始数据,尽管已有国际通用的批量处理软件,但对于高通量表征产生的海量数据进行快速处理还存在难度,国内尚无批量处理程序可用。因此根据实验需求,自行编写了SAXS数据批量处理程序PreSAXS1.0。该程序基于MATLAB平台开发,其功能包括:小角X射线散射实验数据的自动背底扣除、二维散射图像中心定位、样品到探测器距离的校正、批量二维散射图转换成一维曲线。数据以文本格式保存,可直接打开查看并可供相关软件作进一步的分析。     

一种生物X射线小角散射光束线站自动换样溶液蠕动装置

利用同步辐射X射线小角散射技术可以研究溶液中蛋白质的结构信息。但是在实验过程中,高通量的X射线易造成蛋白质的辐射损伤,发生结构变化。本文介绍了一种自动换样溶液样品蠕动装置,在实验过程中利用Hamilton的PSD/4注射泵控制样品上下运动,减小单位体积照射时间以降低X射线对蛋白质的辐射损伤。此外,通过对注射泵、准直调节台和样品/缓冲液支撑台的协调控制实现了自动换样、回样和清洗功能,提高了实验效率。在上海光源生物X射线小角散射实验站进行了实验,通过对静止模式和蠕动模式下溶菌酶的散射曲线及回旋半径的测量,表明该装置可达到很好的防辐射损伤效果,实现了预期的样品蠕动装置功能。     

同步辐射X射线小角散射溶液样品蠕动实验装置的研制

研制了用于同步辐射X射线小角散射实验的溶液样品蠕动实验装置,其主要特点为可有效抑制X射线对溶液样品的辐射损伤、密封性能好、操作简便,且背景散射低、消耗样品量小,还可根据实验要求实现对样品温度的控制,进行变温原位测量。此外,通过实验对该装置的进样量和蠕动速度进行了标定,对防辐射损伤效果进行了验证。结果表明,该装置控制精度高,并可有效减小X射线在测量过程中对样品的辐射损伤。     

小角X射线散射实验数据的初步处理

本介绍北京同步辐射装置(BSRF)小角X射线散射实验站实验数据的初步处理方法，即由成像板探测器检测到的散射信号转换成角度及其对应的强度数据的方法，并对数据转换过程中可能遇到的问题进行了详细的讨论．     

铀生产工艺设备中滞留量测量的自吸收校正方法

实现铀生产工艺设备中滞留量的准确测量是核材料衡算与控制过程的一个关键点。由于γ射线的自吸收效果显著,工艺设备几何结构特殊,无法采用常规校准方法进行数据处理。本文开展该情况下的自吸收校正方法研究,在物料厚度、介质成分、几何参数不确定的条件下,初步建立了自吸收二维校正模型。模拟样品验证表明,建立的自吸收二维校正模型满足铀生产工艺设备滞留量测量的需求。     

同步辐射X射线反射技术及其在测量δ掺杂晶体中原子表层深度分布的应用

X射线低角反射实验技术是测定固体材料表层中杂质原子深度分布的有效手段。利用同步辐射X射线反射技术和近年来发展的由反射实验数据逆向求解原子深度分布的分层逼近法，研究了不同温度下分子束外延生长的δ掺杂（Sb)Si晶体样品，成功地测量了样品中几个纳米范围内的Sb原子深度分布，所得结果表明，300℃以下是用分子束外延方法在Si晶体中生长Sb原子δ掺杂结构的合适温度。     

几何布置对核料位测量性能影响的实验研究

为了研究几何布置对核料位测量工作性能的影响,并找出最佳的布置方式,分别对三种实验装置几何布置进行了实验模拟。结果表明,吸收法精确度最高,散射法次之,工作曲线法最差;从实验过程来看,吸收法和散射法需测多组数据才可得出料位位置;而工作曲线法,当作出工作曲线后,只需测一组数据,就可得出物料的料位位置,此方法更方便、简单和省时。     

Iterative and accurate determination of small angle X-ray scattering background

X-ray scattering is widely used in material structural characterizations.The weak scattering nature,however,makes it susceptible to background noise and can consequently render the final results unreliable.In this paper,we report an iterative method to determine X-ray scattering background and demonstrate its feasibility by small angle X-ray scattering on gold nanoparticles.This method solely relies on the correct structural modeling of the sample to separate scattering signal from background in data fitting processes,which allows them to be immune from experimental uncertainties.The importance of accurate determination of the scaling factor for background subtraction is also illustrated.     

A novel Z-axis diffractometer for X-ray diffraction and fluorescence studies

Recently several X-ray techniques have been demonstrated to have high potential for providing needed structural information to understand the many physical and chemical phenomena that occur at surfaces and interfaces. In this article we will describe an instrument that facilitates the performing of these types of measurements and allows for the investigation of the gas-liquid interface using a variety of synchrotron X-ray scattering techniques. This instrument employs the z-axis diffraction geometry in which the detector has two degrees of freedom while the sample (the gas-liquid interface) has only one degree of freedom — rotation around the vertical axis. A distinctive feature of this diffractometer is that it leaves a fixed illuminated footprint on the liquid interface and allows for an accurate determination of the relative scattering or fluorescence intensity at very shallow angles. The unique capabilities of this novel instrument have been demonstrated at synchrotron facilities in a variety of X-ray techniques: grazing incidence diffraction (GID), shallow angle reflection (SAR), near total external fluorescence (NTEF) and EXAFS experiments from the surface of liquids     

放射性同位素XRF技术中一种与“特散比”法等效的新方法

在一定的条件下,待测元素特征X射线和康普顿散射强度比值,与待测元素特征X射线强度和带吸收滤片所测量的强度比值之间有着简单的双曲函数关系。利用这一函数关系,很容易在单道携带式放射性同位素X射线荧光分析仪上实现“特散比”法改善基体效应。用这种方法所得到的分析结果和用“特散比”法得到的分析结果,二者吻合很好,而且不需要增加任何设备,节省了测量时间和成本。已经测量了几种类型的锡矿样品和某些铜矿样品。     

Soft X-ray ptychography method at SSRF

Ptychography is a diffraction-based X-ray microscopy technique in which an extended sample is scanned by a coherent beam with overlapped illuminated areas and complex transmission function of the sample is obtained by applying iterative phase retrieval algorithms to the diffraction patterns recorded at each scanned position.It permits quantitatively imaging of non-crystalline specimens at a resolution limited only by the X-ray wavelength and the maximal scattering angle detected.In this paper,the development of soft X-ray ptychography method at the BL08U1A beamline of Shanghai Synchrotron Radiation Facility is presented.The experimental setup,experimental parameters selection criteria,and post-experimental data analyzing procedures are presented in detail with a prospect of high-resolution image reconstruction in real time.The performance of this newly implemented method is demonstrated through the measurements of a resolution test pattern and two real samples:Pt-Co alloy nanoparticles and a breast cancer cell.The results indicate that strong scattering specimens can be reconstructed to sub-20 nm resolution,while a sub-25 nm resolution for biological specimens can be achieved.     

The effect of an external electric field on radiation transmission and Compton scattering in plexiglass

The effect of an external electric field on radiation transmission of a plexiglass sample has been studied by using an extremely narrow-collimated-beam transmission method. Also, the photon scattering properties of the charge centers have been determined by changing the charge density distributions of the plexiglass sample with an external electric field having an intensity in the range 0-1000 V/cm. The plexiglass sample was bombarded by 59.5 keV gamma rays emitted from an Am-241 point source. The transmitted and Compton scattered photons were detected by a Si(Li) detector. Appreciable variations were observed in the transmission factors of the plexiglass sample as a function of applied field. The results show that the electrical properties of the plexiglass sample changes with the applied electric field and the gamma ray irradiations although it is a dielectric material. Furthermore, the negatively charged scattering centers are slightly more effective than the positively charged scattering centers in the Compton scattering of gamma rays from an insulator sample, similar to result found for conductor and semiconductors.     

Absolute mass thickness determination of thin samples by X-ray fluorescence analysis

An absolute method for mass thickness determination of thin samples by X-ray fluorescence analysis has been developed. The method is based on the experimental determination of the fluorescence intensities of the sample's constituent elements in reflection and transmission geometries. The samples studied were elemental and compound foils. A set of numerical calculations, Monte Carlo simulations and experimental measurements with thin samples including super-conductor monocrystals were performed with very good results. The range of thicknesses which can be determined by the proposed technique depends on the sample's composition, the excitation energy and the geometrical arrangement.     

BSRF-1W2A光束线弯晶单色器的改进

为解决北京同步辐射装置(BSRF)小角散射实验站样品处光斑的水平聚焦效果差、光斑展宽及光斑水平位置随流强变化有一定的移动等问题,本文设计了一种能够满足实验站稳定用光的新的弯晶单色器.     

Simulation of central sloshing experiments with smoothed particle hydrodynamics (SPH) method

Liquid sloshing phenomena can be observed whenever a liquid in a container has an unrestrained surface and can be excited. A particular type of sloshing motion can occur during the core meltdown of a liquid metal cooled reactor (LMR) and can lead to a compaction of the fuel in the center of the core possibly resulting in energetic nuclear power excursions. This phenomenon was studied in series of “centralized sloshing” experiments with a central water column collapsing inside the surrounding cylindrical tank. These experiments provide data for a benchmark exercise for accident analysis codes. To simulate “centralized sloshing” phenomena, a numerical method should be capable to predict the motion of the free surface of a liquid, wave propagation and reflection from the walls. In this study, a meshless method based on smoothed particle hydrodynamics (SPH) for the simulation of a 3D free surface liquid motion has been developed. The proposed method is applied to the simulation of “centralized sloshing” experiments. Simulation results are compared with the experimental results as well as with results of computations performed with the 3D code SIMMER-IV which is an advanced reactor safety analysis code that implements the traditional mesh-based numerical method. In a series of numerical calculations it is shown that overall motion of the liquid is in a good agreement with experimental observations. Dependence on the initial and geometrical symmetry is studied and compared with experimental data.