X-ray tomography system for industrial applications

X-ray radiography and tomography are two of the most used non-destructive testing techniques both in industrial and cultural heritage fields. However, the inspection of heavy materials or thick objects requires X-ray energies larger than the maximum energy provided by commercial X-ray tubes (600 kV). For this reason, and owing to the long experience of the INFN-Gruppo Collegato di Messina in designing and assembling low energy electron linacs, a 5 MeV electron linac based X-ray tomographic system has been developed at the Dipartimento di Fisica, Università di Messina. The X-ray source, properly designed, provides a 16 cm diameter X-ray spot at the sample position, and a beam opening angle of about 3.6 degree. Optimization of the parameters influencing the e-γ conversion and the X-ray beam characteristics have been studied by means of the MCNP-4C2 (Monte-Carlo-N-Particle, version 4C2) code. The image acquisition system consists of a CCD camera and a scintillator screen. Preliminary radiographies and tomographies showing the high quality performances of the tomographic system have been acquired. Finally, the compactness of the accelerator system is one of the advantages of the discussed tomography device which could be made transportable.     

Two-colored Laser Circulation System for Monochromatic Tunable Hard X-ray Source

A two-colored laser pulse circulation system for a monochromatic tunable hard X-ray source via laser electron Compton scattering is investigated. The demonstration system of the X-ray source is under construction at the University of Tokyo. It consists of the X-band (11.424 GHz) electron linear accelerator and two Nd: YAG laser systems. The main advantage of this system is a monochromatic tunable hard X-ray. It is calculated that the X-ray intensity will be about 10⁸ photons/s. In order to enhance the X-ray intensity for medical applications such as dual energy X-ray CT, a two-colored laser pulse circulation system has been designed. The laser pulse circulation experiment without an electron beam has been carried out by using a Nd: YAG laser fundamental wave (50 mJ) and a second harmonics wave (25 mJ). The result shows that the X-ray intensity can be enhanced by a factor of 10 times higher (i.e., up to 10⁹ photons/s). This work is a part of the JST (Japan Science and Technology Agency) project. The entire X-ray source system is a part of a larger national project on the development of an advanced compact medical accelerator sponsored by the NIRS (National Institute for Radiological Science). The University of Tokyo and KEK are responsible for the X-ray source.     

An intense channeling radiation source

A non-conventional X-ray source which is based on the production of electron channeling radiation in a diamond crystal has been installed at the radiation source ELBE. The brilliant electron beam with an average current of up to 200 μA allows to reach photon rates of quasi-monochromatic channeling radiation between 10¹⁰ s⁻¹ and 10¹¹ s⁻¹ per 10% bandwidth. The photon energy can be tuned by variation of the beam energy. On-line X-ray monitoring was realised at high beam currents using a Compton spectrometer. Monochromisation of channeling radiation and bremsstrahlung background reduction has been investigated applying X-ray diffraction at a highly ordered pyrolytic graphite crystal.     

Measurement of focal spot size in a 5.5 MeV linac

High energy X-ray beams allow to perform analysis on different materials and objects of relevant interest that cannot be investigated with conventional X-ray sources. A 5.5 MeV endpoint energy bremsstrahlung source has been characterized by evaluating the size of X-ray emitting area. In order to perform a proper characterization, an ‘ad hoc’ slit-camera has been designed and a specific technique has been adopted. Due to the characteristics of the beam, a highly attenuating slit with variable aperture has been designed using Monte Carlo simulations of the X-ray beam and set up. Since the slit camera is far from the ideal model (negligible X-ray transmission and very thin aperture), a whole set of image profiles of the slit at different width sizes have been acquired and analyzed. Imaging correction procedures and data fitting lead to satisfactory experimental results according to the theoretical model.     

X-ray microprobe – A new facility for cell irradiations in Kraków

A new, multi-purpose X-ray microprobe has been constructed in Kraków. The Hamamatsu L9191 microfocusing X-ray tube is used as a source of radiation. The microprobe is equipped with three dedicated experimental lines serving for the computed microtomography (CMT), for micro-XRF or TXRF measurements (micro-X-ray induced Fluorescence, Total reflexion XRF) and for mammalian cell irradiations. Details of the construction of the experimental line dedicated to irradiations are presented.     

Energy spectra measurements of X-ray emission from electron interaction in a dense plasma focus device

Electrons generated during a pinch implosion in a hollow anode Mather-like plasma focus device (PF) are considered as a possible X-ray source via the impinging of those particles on medium and high-Z targets. A usual PF device has been slightly modified to optimise the X-ray production and their measurements by means of a suitable and non-invasive spectrometer. This ensemble allows measurements of X-rays generated booth by electrons turning back to the anode and by target collision of the so-called relativistic electron beam. The spectrum of the emitted photons is evaluated by using a differential absorption based technique. The X-ray spectrometer consists of a stack of LiF dosimeters which act both as detectors and filters to give curves of attenuated intensities. Finally, the energy distribution is calculated from such attenuation curves using an iterative procedure based on spectral algebra formalism.     

Synchronize of RF Signal to Femtosecond Laser Pulse Train

作为裂变产物和中子活化产物的^93Zr是一种长寿命纯β放射性核素，它的测量对提供核数据有重要意义。但由于^93Zr放射性衰变计数率低，且^93Nb对^93Zr的测量造成很强的本底干扰，大大影响了^93Zr的超高灵敏测量。AMS是实现^93Zr的超高灵敏测量的方法之一。     

重复频率亚纳秒硬X射线源研制及应用

为获得一种多用途X射线源,满足核辐射探测器研制、脉冲成像等多任务应用需要,本文研制出具备重复频率、超快、高稳定性、便于连续调节脉冲电压和脉宽等的多用途X射线源,其上升沿达98.6 ps,运行电压达425 kV,10 cm处峰值注量率高达2.07×10¹⁸ cm^-2•s^-1,为开展相关应用研究提供了理想的辐射条件。     

Proton induced X-ray fluorescence analysis and its application to the measurement of trace elements in hair

This paper describes the use of proton-induced X-rays as the exciting source in X-ray fluorescence analysis. The possible advantages arising from the virtually mono-energetic nature of this radiation are discussed. A system has been developed using this approach for measuring trace element levels in biological samples and the performance characteristics have been evaluated. The system has been used to analyse a range of specimens and the results of analysis of a set of hair samples are presented as an illustration.     

平行板气体闪烁正比管

本文简述了气体闪烁正比管的原理、基本结构和制作工艺,对~(55)Fe 5.9keV X射线得到的能量分辨率约为9％。     

Si(Li)探测器对体状X射线源的探测效率

本文用蒙特卡罗方法确定Si(Li)探测器对体状X射线源的探测效率。在体状源被压缩到近似点状源的情况下,用模拟方法所得的效率与能量的关系曲线,同标称值有很好的符合。     

Imaging of voids due to deformation in alloy steel using micro-focus X-ray beam

A micro-focus X-ray beam source along with computed tomography technique has been used to image the voids developed during tensile deformation in alloy steel used as structural material for nuclear power plant components. The technique was successful to characterize the internal void structure in the necked region of CrMoV type steel in terms of the size, distribution and volume fraction. The void volume fraction was found to be about 0.03% in a volume of 1.4 mm³ of the necked region reduced in diameter by 32% as a result of tensile deformation.     

康普顿背散射X射线源的初步设计

文章提出一种由北京大学DC-SC光阴极注入器驱动、基于超导加速器和能量回收技术（ERL）的康普顿背散射X射线源的设计方案。理论分析和程序模拟表明,利用该方案可获得具有良好单色性的、高通量X射线。     

Large-area APDs and monolithic APD arrays

In this paper, development of large-area planar avalanche photodiodes (APDs) and monolithic APD arrays for X-ray and scintillation detection is discussed. Single APDs with areas as large as 10 cm² have been fabricated and tested with a CsI(Tl) scintillator (3.8 cm diameter, 2.5 cm height). The resolution of the 662 keV photopeak has been measured to be 9% (FWHM). The X-ray detection performance, gain, and noise of these large APDs have been characterized. Multielement APD arrays have also been fabricated in various formats, such as 4×4 to 14×14 elements (2 mm pixels), and the uniformity of gain, noise, and sensitivity has been evaluated for 4×4 arrays using an ⁵⁵Fe source. Timing properties have been measured. Packaging issues related to the APD arrays are discussed     

A novel compact Tokamak Hard X-ray diagnostic detector

A compact X-ray detector based on the lutetium yttrium oxyorthosilicate scintillator(LYSO) and silicon photomultiplier(Si PM) has been designed and fabricated for the hard X-ray diagnosis on the HL_2A and HL_2M Tokamak devices. The LYSO scintillator and Si PM in small dimensions were combined in a heat shrink tube package, making the detector compact and integrative. The Monte Carlo particle transport simulation tool,Geant4, was utilized for the design of the detector for the hard X-ray from 10 keV to 200 keV and the best structure scheme was presented. Finally, the detector was used to measure the photon spectrum of a ~(137)Cs gamma source with a pre-amplifier and a multichannel amplitude analyzer. The measured spectrum is consistent with the theoretic spectrum, it has shown that the energy resolution of the detector is less than 14.8% at an energy of 662 keV.     

X-Ray Measurement and Enhancement of SBUPF1 Plasma Focus Device in Different Ar Pressures and Operating Voltages

In this paper, best condition of filling gas pressure and operating voltage for SBUPF1 plasma focus device to have maximum intensity of hard and soft X-ray emission has been reported. For time resolved X-ray detection, PIN detector and fast plastic Scintillator detector with appropriate filters have been used and for time integrated X-ray emission measurement, radiography films with appropriate filter masks have been used. Rogowski coil has been used for pinch detection. The highest hard X-ray emission has been observed at the pressure of 0.45 mbar of Argon and discharge voltage about 23.5 kV. The highest Soft X-ray emission has been observed at the pressure of 0.35 mbar of Argon and discharge voltage about 23.5 kV. For enhancement of hard X-ray emission intensity, lead disk was placed in copper anode tip and measurements were repeated. Results have shown that hard X-ray emission has been enhanced about 23% and soft X-ray emission has been enhanced about 33% with inserting a high atomic number metal disk like lead. Results from integral X-ray measurement have shown presence of dominant peaks in ranges 13.2–15, 21–21.9 and 23.4–24.3 keV with significant spectral components in the range of 0–50 keV. Pinch size has measured with pin hole camera and it is about 0.6 mm × 2.12 mm. Captured images with SBUPF1 have confirmed that it is a suitable source for introspective imaging with capability of showing very fine details.     

一个基于EPICS框架的EPU前端反馈系统

插入件是现代光源重要组成设备之一,其质量直接影响上海光源整体性能。由于建造和安装工艺的限制,插入件的磁场会对束流轨道稳定性产生影响。为降低对束流的扰动,在插入件电子束流入口和出口位置增加校正线圈实现自动补偿功能。因此我们设计了基于EPICS的插入件前端反馈系统,经测试,该前馈系统用户界面简洁,反馈控制功能完整可靠,实时性高,提高了束流的稳定性,为试验站稳定供光提供了保证。     

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 new X-ray source using backscattered X-ray with the use of a cold cathode

The development of an intense X-ray source using backscattered X-ray produced using an advanced electrode configuration is described. The electrodes were composed of field emitters deposited on a wire mounted on a perforated plate as the cathode and a copper plate as the anode. Electrons from these emitters collided with the copper plate and X-ray was generated at collision points. The backscattered X-ray in the direction normal to the electron trajectory through a hole in the anode escaped from the vacuum chamber through a beryllium window. Continuous and characteristic X-rays were detected at an applied voltage lower than that of a conventional X-ray source from 3.0 to 9.4 kV, respectively. Moreover, the X-ray dosage measured with a survey meter reached 0.95 mSv/h at 5.0 kV of applied voltage. The transmission images of three types of material used as an X-ray source for the X-ray imaging system indicate three advantages; low power consumption, focal point controllable by adjusting applied voltage, and photographable motion picture of X-ray transmission.