Journal of X-Ray Science and Technology - Volume 5, issue 2
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Journal of X-Ray Science and Technology is an international journal designed for the diverse community (biomedical, industrial and academic) of users and developers of novel x-ray imaging techniques. The purpose of the journal is to provide clear and full coverage of new developments and applications in the field.
Areas such as x-ray microlithography, x-ray astronomy and medical x-ray imaging as well as new technologies arising from fields traditionally considered unrelated to x rays (semiconductor processing, accelerator technology, ionizing and non-ionizing medical diagnostic and therapeutic modalities, etc.) present opportunities for research that can meet new challenges as they arise.
Abstract: We present experimental and theoretical studies of the diffraction by an x-ray lamellar multilayer amplitude grating. The main diffraction properties of such a device are given. Experimental efficiency curves are obtained at 800 eV photon energy using synchrotron radiation. The features observed in these curves are identified and interpreted by means of two theoretical methods. Particular emphasis is given to structures observed for the first time which had been theoretically predicted.
Abstract: The engineering aspects of a nine-channel digital radiographic system developed for bioimaging research, based on high gas pressure ionography and kinestatic principles, are presented. The research imaging system uses a pulsed x-ray beam which allows one to study simultaneously the ionic signal characteristics at 10 different ionization sites along the drift axis. This research imaging detector system allows one to investigate methods to improve the detection and image quality parameters as part of the development of a large scale prototype medical imaging system.
Abstract: Ultra thin silicon foils with thicknesses below 100 nm and large diameters have been produced. Foils with a thickness of 50–60 nm have been used as supporting foils for zone plates and as vacuum windows withstanding a pressure difference of 1 atm.
Abstract: A performance model for an x-ray imaging camera that is currently being developed at York University for the recording of crystallographic diffraction patterns produced by synchrotron radiation is presented. The camera is based on charge coupled device (CCD) sensors which are coupled to a CsI(Tl) x-ray scintillator screen using 3:1 reducing fiber optic tapers. The model predicts the accuracy to which diffraction spot intensities can be measured over a range of incident x-ray flux. The effect of the point spread function of the scintillator and optics and the typical expected diffraction spot geometry is included in the model and shown…to have the most significant effect on the system performance for low spot intensities, limiting the camera's effective dynamic range. However, it is shown that quantum limited performance for incident dose fluxes as low as 100 photons per spot can be readily achieved in this design. Finally, the camera performance is predicted for x-ray energies above the scintillator K absorption edges (>33 keV). The effects of energy loss through scintillation K shell fluorescent escape photons reduces the camera’s detective quantum efficiency.
Abstract: Ray tracing calculations for crystal-diffraction spectrometers with position-sensitive detectors are done. After describing fundamentals of the ray tracing formalism, the paper presents selected results for a given spectrometer geometry. The developed method allows a three-dimensional representation of diffraction reflections as well as a matrix display of the recorded events in the detector plane. Applying the formalism of Monte Carlo simulation it is possible to calculate other important quantities, such as the resolving power and luminosity of the analyzed spectrometer.
Abstract: Gas ionization x-ray detectors operating at pressures up to 100 atm offer inherently high spatial and contrast resolution. However, incorporating the detector x-ray entrance window in a conventional pressure vessel designed for such pressures can result in high primary beam loss in the window and a much reduced overall detective quantum efficiency. The design of a gas chamber cover plate for a strip beam detector which mechanically isolates the x-ray entrance window from the lateral tensile stresses in the chamber body is described. A number of test windows of this design, varying in three geometric parameters—thickness, window curvature, and fillet…radius—were fabricated from wrought aluminum [6061-T651 ] and subjected to pressures of up to 400 atm for the purpose of selecting an optimum window for a prototype digital x-ray imaging detector. The experimental data indicate that windows can be designed for a detector admitting a 1.0 cm wide x-ray beam that have rupture pressures exceeding 500 atm while maintaining x-ray transmittances of as much as 93.4% for a 120 kVp tungsten anode spectrum.