Journal of X-Ray Science and Technology - Volume 9, issue 1

Authors: Lunt, Shannon | Turley, R. Steven | Allred, David D.

Article Type: Research Article

Abstract: We designed multilayer mirrors for the IMAGE/Explorer mission that were intended to reflect well at 304 * and poorly at 584 *. The best designs utilized the novel materials U and Y_2 O_3 with Al or Si as spacer layers. The highest design reflectivities were obtained with aperiodic multilayers, although these were too hard to grow in practice. We found these novel designs using a genetic algorithm calling on a database of 43 promising …materials with the freedom of aperiodic multilayer stacks. Show more

Citation: Journal of X-Ray Science and Technology, vol. 9, no. 1, pp. 1-11, 2001

Authors: Kunze, H.-J. | Juschkin, L. | Ellwi, S.

Article Type: Research Article

Abstract: The possible emission from dense plasmas produced in discharges is analyzed with respect to optimize the achievable radiance at 11.5 and 13.5 nm for applications in EUV lithography, although the considerations may readily be applied to other spectral regions and to laser-produced plasmas. Density and temperature requirements of the plasma are discussed. Once an emission line has been selected, the optimum temperature of the plasma for quasi-steady state conditions is around the temperature for maximum fractional …abundance of the respective ion, and the maximum possible radiance is given by the Planck function. Suitable lines are identified and discussed. Show more

Citation: Journal of X-Ray Science and Technology, vol. 9, no. 1, pp. 13-18, 2001

Authors: Jiang, Hangyi | Liu, Hong | Chen, Wei R.

Article Type: Research Article

Abstract: A simple method for determination of the geometric parameters of monoplane stereo x-ray system is proposed in this paper. According to the principle of perspective projection, a monoplane stereo imaging model was established. The geometric parameters required for 3D point recovering were described. Applying the perspective projection rule and similar triangles concept, the system geometry can be calculated with three calibration line segments in 3D space. Calibration accuracy analysis has been performed. A cube …phantom with radio-opaque line segments of known length and orientation is employed during calibration procedure. Experiments were carried out using a CCD based monoplane stereo x-ray system prototype. The results are consistent with the expected value predicated by theoretic analysis. Our promising application of this technique for the system calibration lies in digital mammography imaging guidance, but applications in other type of radiographic imaging are possible also. Show more

Citation: Journal of X-Ray Science and Technology, vol. 9, no. 1, pp. 19-28, 2001

Authors: Fraenkel, Benjamin S. | Bitter, Manfred

Article Type: Research Article

Abstract: Recently X-ray spectrometers with spherically curved large crystals, which are designed for the diagnostics of extended X-ray sources, have been shown to reach a throughput of an order of magnitude more than the usual cylindrically curved Johann crystal spectrometers, for large Bragg angles. Here, the possibility of applying 2D curving also to ground and curved Johansson crystals is discussed, to further enhance the throughput.

Citation: Journal of X-Ray Science and Technology, vol. 9, no. 1, pp. 29-33, 2001

Authors: Fedorenko, A.I. | Pershin, Yu.P. | Poltseva, O.V. | Ponomarenko, A.G. | Sevryukova, V.S. | Voronov, D.L. | Zubarev, E.N.

Article Type: Research Article

Abstract: The structure, phase and chemical compositions of Sc/Si multilayer XUV mirrors (MLMs) were studied by cross-sectional electron microscopy, hard X-ray (\lambda =0.154 nm) diffraction and X-ray microanalysis. In as-deposited state Sc/Si MLMs with periods D>18 nm consist of polycrystalline Sc- and amorphous Si-layers divided by intermixed amorphous zones (IAZs) with thickness around \sim 3 nm on each interface. A few percent of oxygen in Sc layers …is responsible for its FCC structure instead of stable HCP one. According to simulations, composition and density of IAZs are close to silicide ScSi. Integral diffusivity of Sc-Si alloys during formation of IAZs in the process of multilayer growth was 10^{-14} --10^{-15} cm^2 /s. Deposited by e-beam evaporation Sc/Si MLMs have interface roughness as high as 2.5 nm exceeding by a factor of two those produced by magnetron technology. Heating up to 500^{\circ} C is accompanied by planar broadening of IAZs with substantial period decrease, reaching up to 12% with D=24.5 nm. After annealing at 500^{\circ} C MLM of crystalline Sc_3 Si_5 /amorphous Si was formed instead of the original one. The periodic structure of MLMs deteriorated after annealing at 530^{\circ} C for one hour. Show more

Citation: Journal of X-Ray Science and Technology, vol. 9, no. 1, pp. 35-42, 2001

Authors: Lee, H.-R. | Ellingson, W.

Article Type: Research Article

Abstract: The characteristics of an amorphous silicon detector for use in an X-ray imaging system have been evaluated. The primary use of the detector is in a three-dimensional (3-D) computed tomography (CT) system. The detector is a two- dimensional (2-d) flat panel array consisting of a 1024 \times 1024 matrix of photodiodes placed on a 100-\mu m center. Combined with a Lanex(tm) scintillator, the detector-sensor presents an ideal solution for high-resolution industrial X-ray …imaging applications. Modulation transfer function (MTF), determined from a 2-D projection image of a line-pair phantom, shows that the detector can achieve a resolution of 140 \mu m at 50% contrast, and a resolution of approximately one pixel (100 \mu m) at 20% of maximum image contrast. Further, examination of monolithic ceramic material with projection data from this detector demonstrates that such a flat-panel detector has promise for use in a CT system to provide highly resolved information. The reconstructed CT image of a ceramic hole-phantom demonstrates that the smallest holes (with a diameter of 300 \mu m) can be detected with a spatial resolution of \sim 150 \mu m at 50% contrast. Show more

Citation: Journal of X-Ray Science and Technology, vol. 9, no. 1, pp. 43-53, 2001