同步辐射软X射线对单细胞的辐射损伤

应用国家同步辐射实验室软X射线显微术光束线的光学系统,搭建了适合软X射线单细胞辐照损伤效应研究的实验装置,选择氧元素K吸收边能量对Hela细胞进行单细胞辐照,运用单细胞凝胶电泳技术进行辐照损伤评价.实验结果表明,辐射损伤效应与辐射剂量有依赖性关系.     

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.     

NSRL软X射线磁性圆二色光束线

本文对合肥同步辐射（NSRL）二期工程软X射线磁性圆二色光束线进行了介绍。束线主要包括斩波器系统、前置镜系统、单色器系统、后置镜系统、真空系统、软件及电子学系统。光束线的预期指标为：光通量10^8s^-1,实验站的波长范围为100-1000eV,圆偏振度0．6-0．8（随波长变化而变化）,在1000ev处的能量分辨率为1000,在实验站的焦点处光斑大小为水平方向3mm,垂直方向1mm。     

软X射线激发稳态瞬态发光探测系统研制

在上海同步辐射光源软X射线显微谱学光束线站BL08U1A搭建了软X射线激发稳态瞬态发光探测系统,可探测紫外到近红外波段的光子(200～900 nm),实现了常规软X射线激发发光光谱(X-ray Excited Optical Luminescence,XEOL)和时间分辨XEOL(Time-resolved XEOL,TRXEOL)光谱探测。通过将光谱仪数据采集程序与该实验站原有的数据采集软件集成,实现了不同X射线能量激发下XEOL和全电子产额谱(Total Electron Yield,TEY)的同时检测。基于该探测平台,获得了CsPbI3亚微米线样品在Cs元素M4,5边的二维XANES-XEOL谱图,并研究了光子晶体对闪烁体光输出的影响。基于TRXEOL探测平台,成功获得了ZnO样品在不同时间窗下的XEOL谱和发光衰减曲线。实验结果表明:BL08U1A实验站具备XEOL和TRXEOL探测能力,为研究材料的发光机制和发光动力学过程提供了很好的技术手段。     

YAG晶体在软X射线荧光靶探测器中的应用

荧光靶探测器是同步辐射光源光束位置定位的重要设备之一,本文在96 500 eV软X射线内对CVD金刚石薄片和Ce:YAG晶体薄片进行光致发光亮度的测试,观察到Ce:YAG在该能量段的发光亮度比金刚石高,完成了上海光源软X射线荧光靶探测器靶材的实验研究与探测器的设计;同时给出了YAG晶体荧光靶探测器在线使用时观察到的相干光的衍射图像。     

面形误差对自由电子激光聚焦光斑影响的研究

正在建设中的上海软X射线自由电子激光(Self-amplified Spontaneous Emission,SASE)光束线—活细胞成像光束线,能量范围100～1 000 eV,束线主要设备包括前端区、插入件、偏转平面镜PM1、诊断光栅PM2、单色器、压弯镜、KB镜(Kirkpatrick-Baez)和椭球镜等。分为两条支线,其中北支线的KB镜组由一个平面镜和两个椭圆柱面镜构成,主要应用于生物细胞成像实验站。实际光学元件在加工过程中会存在一定的面形误差,面形误差是衡量光学元件表面质量的重要指标。自由电子激光光束线系统中,要求镜子表面具有高精度和高可靠度,镜子的面形和高度误差相关联,会影响光束的相干性和波前,进而影响最终的光斑。为了准确研究面形误差对X光经过光束线传播后相干性和波前变化的影响,使用软件SHADOW和SRW对北支线X光的传播进行模拟。模拟结果表明:平面镜面形误差控制在0.1～0.2μrad,同时椭圆柱面镜控制在0.4μrad以内,聚焦光斑尺寸在4μm以内,可满足生物成像实验站成像需求。该结果为软X射线自由电子激光的优化设计提供了参考和依据。     

微通道板在软X射线能区的绝对标定

在北京同步辐射装置(Beijing synchrotron radiation facility,BSRF)的3W1B软X射线光束线上利用Si光电二极管传输标准探测器对微通道板(Microchannel plate,MCP)探测器进行了能量响应效率的绝对标定.给出了能量范围在50-250eV的能量响应的标定结果,并给出了标定的不确定度.利用标定后的MCP对同步辐射光束线能谱及偏振特性进行了测量,得到了理想的结果.     

北京同步辐射软X射线装置与软X射线探测器标定

软X射线计量标准的建立和软X射线探测器标定是目前国内急需解决的课题，本简单介绍了两套北京同步辐射软X射线装置，它们主要用于软X射线光学元件测量和软X射线探测元、器件的标定。另外给出了近年来在软X射线测量装置上开展的计量标准和探测器标定方面的研究结果。     

北京同步辐射装置3B3光束线吸收谱测量及装置设计

介绍了在北京同步辐射装置(BSRF)3B3中能光束线(1.2～6.0keV)进行X射线吸收谱(XAS)的简易装置,并利用透射法对低原子序数元素(S、P、Cl、Ca、Al、Mg等)进行X射线吸收谱测量,分析结果表明在3B3中能X射线能区开展吸收谱学研究工作是可行的.根据计算X射线吸收谱信号的结果,设备设计满足测量要求,一套包含3种X射线吸收谱测量方式(透射法、荧光法和电子产额法)的精密设备正在建设,将有利于中等能区X射线谱学研究工作的广泛开展.     

北京同步辐射软X射线装置与软X射线探测器标定

简单介绍了2套北京同步辐射软X射线装置，主要用于软X射线光学元件测量和软X射线探测元、器件的标定。给出了在软X射线测量装置上计量标准和探测器标定方面的研究结果。     

北京同步辐射软X射线偏振测量装置及其应用

在北京同步辐射装置(BSRF)设计建造了-套基于多层膜偏振元件的软X射线偏振测量分析装置,可工作在双反、双透、前反后透和前透后反四种工作模式,既可作为偏振测量装置,用于同步辐射光束线和多层膜偏振元件偏振特性测量,也可作为通用反射率计,用于多层膜和薄膜的反射或透射率测量,又可用于磁性材料的磁光效应研究等.利用自行研制的装置和光学元件对BSRF的3W1B光束线的偏振特性进行了系统的测量.测量结果指出,在206 eV时,输出光的线偏振度从起偏前的O.585上升到起偏后的0.995,同步光的线偏振度得到极大改善.利用非周期宽带Mo/Si多层膜开展了铁磁性材料的磁光法拉第效应测量,获得了Ni薄膜3p边附近(60-70 eV)的法拉第旋转角度,最大偏转角度在65.5 eV和68 eV分别为1.85±0.19°和-0.75±0.09°.     

Proton bremsstrahlung and its radiation effects in fusion reactors

Protons and neutrons are emitted in many fusion processes of light nuclei. In a fusion reactor, a proton and a neutron thus generated may again fuse with each other. Or they can in turn fuse with or be captured by an un-reacted nuclear fuel, for example deuterium. The average center-of-mass energy for such reaction is around 10 keV in a typical fusion reactor. At this low energy, the reacting nucleons are in an s-wave state in terms of their relative angular momentum. The single-gamma radiation process is thus strongly suppressed due to conservation laws. Instead the gamma ray released is likely to be accompanied by soft X-ray photons from a nuclear bremsstrahlung process. The generated soft X-ray has a continuous spectrum and peaks around a few hundred eV to a few keV. The average photon energy and spectrum properties of such a process are calculated with a semi-classical approach, with the explicit example of proton-neutron capture. This phenomenon may have been observed in some prior tokamak discharge experiments, and its interpretation is complicated by the presence of electron bremsstrahlung. However, it also opens up the possibility of new plasma diagnostics which are more sensitive to the ionic or nuclear degree of freedom.     

A windowless ionization chamber for soft X-ray dosimetry

A new simplified model of a free air ionization chamber called a windowless air ionization chamber (WIC), for kerma in air measurements from the soft X-ray sources, has been designed and tested. The design is based on Monte Carlo calculations. The assembled WIC for testing has the electrodes in the form of half cylinders (internal diameter 36 mm; internal length 85 mm). The volume of the collecting sector of this chamber is around 1 cm³. An entrance aperture has 6 mm diameter. The results of MC calculations and tests for X-ray qualities: ranging 0.3-0.7 mm Al HVL are given.     

Hydrogen ion desorption from amorphous carbon films induced by resonant core electron excitations

In order to get insight into the mechanism of structural change in tetrahedral amorphous carbon (ta-C) films that is induced by soft X-ray illumination at photon energies near the carbon core edge, the desorption of ions from ta-C films, as a possible process taking place concurrently with the photo-induced restructuring, was studied by time-of-flight (TOF) measurements of photo-ions as a function of photon energy. The results show that (1) the main ions detected are H⁺, (2) the desorption efficiency spectra exhibit a resonant peak at 286-287 eV which is common to all detected ions, and (3) is 3 eV lower than the resonant peak in the efficiency spectrum of photo-induced restructuring. These rule out the hypothesis that it is the photo-induced C-H bond rupture that causes the resonant soft X-ray-induced restructuring in ta-C films.     

高功率Z箍缩软X射线功率测量

针对“强光一号”装置喷氪气高功率Z箍缩等离子体实验产生1keV以下的软X射线，研制了脉冲恒压电源驱动的镍薄膜量热计，测量Z箍缩软X射线总能量，用快时间响应的X射线二极管(XRD)探测器建立了软X射线功率测量系统，给出了实验测量结果。     

The Columbia University proton-induced soft x-ray microbeam

A soft X-ray microbeam using proton-induced X-ray emission (PIXE) of characteristic titanium (K_α 4.5 keV) as the X-ray source has been developed at the Radiological Research Accelerator Facility (RARAF) at Columbia University. The proton beam is focused to a 120 μm × 50 μm spot on the titanium target using an electrostatic quadrupole quadruplet previously used for the charged particle microbeam studies at RARAF. The proton induced X-rays from this spot project a 50 μm round X-ray generation spot into the vertical direction. The X-rays are focused to a spot size of 5 μm in diameter using a Fresnel zone plate. The X-rays have an attenuation length of (1/e length of ∼145 μm) allowing more consistent dose delivery across the depth of a single cell layer and penetration into tissue samples than previous ultrasoft X-ray systems. The irradiation end station is based on our previous design to allow quick comparison to charged particle experiments and for mixed irradiation experiments.     

Development of a soft X-ray microprobe for single cell radiobiology

An X-ray microprobe for radiobiological studies was developed which deliver precise doses of radiation to the selected individual cells. The facility used synchrotron radiation as soft X-ray source. A zone plate combining with a pinhole produced a fine probe from bending magnet for single cell irradiating with defined doses. The diameter of microprobe at the target position was about 2 μm by scanning a knife-edge with an AXUV photo diode. The fluxes of soft X-rays at 516.7 eV (2.4 nm) were about 5.4×104 photons/s.100mA measured with the photo diode. The absorbed dose rate for typical yeast cells was about 11.34 Gy/s with the storage current of 100 mA. A preliminary experiment for yeast cells irradiation has shown that the microprobe had a definite biological effect for radiobiological investigations. The soft X-ray microprobe at "water window" region has provided a useful tool for single cell irradiating damage and a capability of individually irradiating a certain numbers of cells each time.     

细胞样品的高分辨率软X射线接触显微术图像的研究

在建立适于软Ｘ射线接触显微术（ＳＸＣＭ）观察细胞样品制备方法的基础上，以培养的肿瘤细胞为生物样品，应用细聚焦软Ｘ射线光源进行ＳＸＣＭ研究，获得了分辨率优于２８ｎｍ的高质量肿瘤细胞ＳＸＣＭ图像。