Vol.8 No.2 2015

Research paper : Application of laser Compton photon beam to nondestructive tests (H. TOYOKAWA)−94−Synthesiology - English edition Vol.8 No.2 (2015) magnet that can achieve highly precise magnetic field; and improvement in bunch charge density and management of severe space charge effect. Downsizing and weight reduction are also necessary for all parts being used. It is difficult to achieve full performance equivalent to that of a large accelerator system with a small accelerator system. The best way is to develop an electron accelerator of specific performance for specific usage, with a moderate cost.Now, the usefulness and the problem of an industrial high-energy photon CT system became clear. Unlike the medical X-ray CT system, various materials are the subjects of measurement in industrial radiography. So, it is important to accurately measure the shape, outer and inner sizes, and the density distribution of industrial products using a high-energy X-ray CT system. A research project to evaluate the precision and reliability of the measurement of the inner structure of industrial products obtained with CT images compared with other methods, such as a three-dimensional coordinate measuring machine, is being conducted, as one of the important translational research projects for industry.[12]4 Future developmentsAt present, the present research has entered the phase of investigating downsizing and weight reduction of the electron accelerator for a specific purpose. A 0.9 MeV portable electron accelerator system for infrastructure measurement is being developed. We use a coniferous carbon nanostructure (CCNS) material[13] as an electron emitter for the electron gun to minimize the system size and weight. We started up a project to build a radiography system that observes the internal part using backward scattering of X-rays, and to apply this system to nondestructive tests for infrastructures.[14]Although it may be a repetition of the first chapter, the scenario of the present research is as follows.(1) Development and compilation of elemental technologiesFig. 7 (Left) Plot of the linear attenuation coefficients of various materials and the CT values expressed by HU.[10] The symbols in the diagram represent the substances, e.g. D2O = heavy water.Fig. 8 Improvement of elemental technologies, elements that determine the performance index, and relationship of the sophistication of devices and methods 10 mm attenuation coefficient (cm-1)Hounsfield unit(×103)Barium fluoride : BaF2Chrome : CrMagnesium : MgCopper : CuAluminum : AlHeavy water : D2OLight water : H2OSilicon : Si ImprovementImprovementImprovementImprovementImprovementImprovementImprovementEase of measurement (automation, etc.)Values setPhoton beam intensityValues setValues setDevice, methodElements that determine performance indexesImprovement of elemental technologiesPerformance indexesSubject to be measuredCost-effectiveness ratioElectron accelerator control systemPhoton beam luminanceDegree of stability of photonsSpatiotemporal collision precision of lasers and electronsIndustrial radiographyTemporal resolution (measurement time)Density resolutionSpatial resolutionDetector sizePhoton beam diameterOptimal photon energy


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