Berlin 2005 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 42: Instrumentation und Anwendungen

HK 42.7: Talk

Wednesday, March 9, 2005, 15:45–16:00, TU MA042

Investigation of Axial Channelling of 600 MeV Electrons in Silicon Single Crystals at the Mainz Microtron MAMI — •H. Backe, W. Lauth, A. Rueda, M. El Ghazaly, P. Kunz, and T. Weber — Institut für Kernphysik der Universität, D-55099 Mainz

The flux of electrons impinging on a single crystal close to an axial channel is redistributed in transverse energy and impact parameter due to multiple scattering which results either in bound trajectories of spiral type or chaotic unbound motion of the electrons in the two dimensional potential energy surface of the crystal. To study these motions in more detail we initiated experiments at the Mainz Microtron MAMI which are based on the measurements of the 1.74 keV characteristic X-ray yields after K-shell ionization. The small absorption length of 12.2 µm for the K X-rays allows insight into the channelling process directly at the exit interface of the crystal even if the electron traversed a rather thick layer. A surprisingly large enhancement of the K X-ray yield has been observed at channelling of 600 MeV electrons along the [100] strings of silicon indicating small impact parameters and a rapid dechanneling. In addition, a very strong enhancement of intensity at a photon energy of 60 keV was observed with a CdZnTe detector positioned in forward direction which might be explained by synchrotron radiation like emission at deflection of the electrons in their chaotic unbound motion.

Work supported by Deutsche Forschungsgemeinschaft DFG under contract BA 1336/1-3.