Journal of X-Ray Science and Technology - Volume 2, issue 2

Authors: Christensen, F. E. | Hornstrup, A. | Frederiksen, P. | Grundsøe, P. | Henrichsen, S. | Jacobsen, E. | Jonasson, P. | Madsen, M. M. | Nilsson, C. | Schnopper, H. W. | Westergaard, N. J. | Ørup, P.

Article Type: Research Article

Abstract: A versatile x-ray diffractometer is described in detail. Two applications to the study of x-ray optical elements are presented. The first is a Bragg reflection study of state-of-the-art multilayers deposited both on conventional Si-wafer substrates and on superpolished substrates such as fused quartz and electroless nickel. These data are compared to data previously obtained at FeKα. The second study is a reflectivity and scattering study of various thin-foil x-ray reflectors proposed for up-coming x-ray satellite missions. All the data have been obtained at MgKα = 1.2536 keV.

DOI: 10.3233/XST-1990-2201

Citation: Journal of X-Ray Science and Technology, vol. 2, no. 2, pp. 81-94, 1990

Authors: Niu, Aiqun | Han, Chia Yung | Wee, William G.

Article Type: Research Article

Abstract: Three-dimensional image reconstruction plays a very important role in noninvasive diagnosis of biological systems and nondestructive evaluation of manufactured work-pieces. A new direct three-dimensional reconstruction algorithm, called TART (Three-dimensional ART), is presented in this paper. Oblique projection data are used and an ART-based algorithm is introduced to compensate for the limiting constraints of incomplete projection and/or limited angular coverage. The fact that oblique projection gives useful information to the reconstruction algorithm is shown mathematically. The algorithm can be used to solve the reconstruction problem under the conditions of both complete data and incomplete data. The algorithm first maps geometric information …and projection data from an oblique plane into a horizontal plane, then calculates the weighting factors for the voxels based on this horizontal plane, and finally performs a 3-D ART reconstruction. Two experimental results illustrate the superiority of the algorithm over the previous reconstruction methods. Show more

DOI: 10.3233/XST-1990-2202

Citation: Journal of X-Ray Science and Technology, vol. 2, no. 2, pp. 95-116, 1990

Authors: Chapman, H. N. | Nugent, K. A. | Wilkins, S. W. | Davis, T. J.

Article Type: Research Article

Abstract: Focusing and collimation of 8 keV x rays has been demonstrated using microchannel plate (MCP) blanks with cylindrical channels. The focusing effect arises from total external reflection of x rays at the interior surfaces of the channels of a MCP and has been described previously by the authors. Point to point focusing was observed with flat and curved MCPs, and collimation from a point source to a quasi-parallel beam was observed with a curved MCP. Intensity profiles at the image plane and at other planes behind a flat MCP were obtained for a 20 × 40 μm2 x-ray source, …and agree well with theoretical predictions. The flux in a 40-μm-diameter collector in the image plane was compared with the flux in the same plane, but without a MCP. The relative gain in flux increases linearly with the source to MCP distance, as predicted. A maximum relative gain in flux of 18 ± 1 was observed for a source to detector distance of 50 cm. Show more

DOI: 10.3233/XST-1990-2203

Citation: Journal of X-Ray Science and Technology, vol. 2, no. 2, pp. 117-126, 1990

Authors: Murakami, M. | Meyer-Ter-Vehn, J. | Ramis, R.

Article Type: Research Article

Abstract: The conversion of ion beam energy into thermal x-ray radiation by means of stretched cylindrical plasma volumes is studied by analytic modeling and numerical simulation. The analysis is restricted to one-dimensional radiation hydrodynamics. Scaling relations for different materials are derived. Due to equation-of-state properties, high-Z material turns out superior for achieving high conversion efficiency. The paper provides practical answers for thermal x-ray generation with intense heavy ion beams. Deposition powers in the order of 10l6 W/g are required for applications to ion beam inertial confinement fusion.

DOI: 10.3233/XST-1990-2204

Citation: Journal of X-Ray Science and Technology, vol. 2, no. 2, pp. 127-148, 1990

Authors: Rodé, A. V. | Maksimchuk, A. M. | Sklizkov, G. V. | Ridgeley, A. | Danson, C. | Rizvi, N. | Bann, R. | Forster, E. | Goetz, K. | Uschmann, I.

Article Type: Research Article

Abstract: A novel method of measuring absolute x-ray wavelengths using simultaneous Bragg reflections at two parallel crystal plates of equal atomic spacing is presented. The accuracy of wavelength determination Δλ/λ for this method is discussed and a value of 5 × 10−5 is achieved. Absolute wavelengths of L-shell laser-produced spectra of Cu, Ge, As, and Se and M-shell spectra of Gd and Tb have been measured in the wavelength region 7.5–8.5 Å using a quartz (10T0) quasimonolithic crystal blank.

DOI: 10.3233/XST-1990-2205

Citation: Journal of X-Ray Science and Technology, vol. 2, no. 2, pp. 149-159, 1990