1. Novel Digital K-Edge Imaging System with Transition Radiation from an 855-MeV Electron Beam
- Author
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Hagenbuck, F., Backe, H., Clawiter, N., Euteneuer, H., Gorgen, F., Holl, P., Johann, K., Kaiser, K.-H., Kemmer, J., Kerschner, Th., Kettig, O., Koch, H., Kube, G., Lauth, W., Matthay, H., Schutrumpf, M., Stotter, R., Struder, L., Walcher, Th., Wilms, A., Zanthier, C. v., and Zemter, M.
- Subjects
Imaging systems -- Evaluation ,Image processing -- Digital techniques ,Charge coupled devices -- Usage ,Business ,Electronics ,Electronics and electrical industries - Abstract
A novel K-edge imaging method has been developed at the Mainz Microtron MAMI aiming at a very efficient use of the transition radiation (TR) flux generated by the external 855-MeV electron beam in a foil stack. A fan-like quasi-monochromatic hard X-ray beam is produced from the [+ or -] -1-mrad-wide TR cone with a highly oriented pyrolytic graphite (HOPG) crystal. The absorption of the object in front of a 30 mm x 10 mm pn charge-coupled device (pn-CCD) photon detector is measured at every pixel by a broad-band energy scan around the K-absorption edge. This is accomplished by a synchronous variation of the lateral crystal position and the electron beam direction which defines also the direction of the TR cone. The system has been checked with a phantom consisting of a 2.5-btm thick molybdenum sample embedded in a 136- or 272-[micro]m-thick copper bulk foil. A numerical analysis of the energy spectrum for every pixel demonstrates that data as far as [+ or -] 0.75 kev away from the K edge of molybdenum at 20 kev still improve the signal-to-noise ratio (SNR). Prospects are discussed to investigate the human lungs with xenon as a contrast agent at the available total primary photon flux of 2 x [10.sup.10]/(s [multiplied by] 0.1% bandwidth (BW)) only. Index Terms--Highly oriented pyrolytic graphite (HOPG) crystal, K-edge imaging, pn charge-coupled device (pn-CCD), transition radiation.
- Published
- 2001