Channeling and Photon Emission of Electrons in Crystalline Undulators-Experiments
Zusammenfassung der Projektergebnisse
Dechanneling length measurements for silicon single crystals, performed for electron beam energies between 195 and 855 MeV at the Mainz Microtron MAMI, have been reanalyzed under more realistic model assumptions. The results for the (110) plane suggest that below an electron energy of about 350 MeV low lying quantum states in the channeling potential pocket enlarge the dechanneling length in comparison with classical expectations. On the way to realize a crystal undulator, the dechanneling process has also been studied for a bent crystal with a bending radius of 33.5 mm at a beam energy of 855 MeV. The experimental results for the (111) plane have been interpreted with the aid of Monte Carlo simulations. The extracted dechanneling length of 16.5 µm is in accord with the results obtained by the former method for the (110) plane. Experiments with a 4-period epitaxially grown strained-layer Si1-xGex undulator with a period length of 9.9 µm and large amplitude of about 5 Å have been performed at various electron beam energies between 195 and 855 MeV. In all experiments a clear enhancement of radiation in the expected low energy domain has been observed. Analysis with a simple analytical model suggests that the gross structure can be explained by synchrotron-like radiation emitted from small arc elements of the undulator. For the beam energies of 270 and 375 MeV additional humps appear at the expected peak energies of 0.069 and 0.132 MeV, respectively. The results suggest that evidence for a weak undulator effect has been observed for the first time for electrons. In addition, a novel scheme of a Si1-xGex crystalline undulator with a small amplitude for the (110) lattice plane of only 0.12 Å and a period length of 0.43 µm has been tested at MAMI at beam energies of 600 and 855 MeV. Peak structures have been observed at the expected photon energies of 7.94 MeV and 16.2 MeV, respectively. Since for both types of undulators the intensities of the peaks are much smaller than expected, the quality of the epitaxially grown undulators have been or will be investigated by x-ray topography methods at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France.
Projektbezogene Publikationen (Auswahl)
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Channeling experiments with electrons at the Mainz Microtron MAMI. International Journal of Modern Physics A Vol. 25, Supplement 1 (2010) 136-143
W. Lauth, H. Backe, P. Kunz, A. Rueda
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Photon emission of electrons in a crystalline undulator. Charged and Neutral Particles Channeling Phenomena, Channeling 2008, Proceedings of the 51 st Workshop of the INFN ELOISATRON Project, 25 October - 1 November 2008, Erice, Italy, Editors Sultan B. Dabagov & Luigi Palumbo, World Scientific 2010, p. 281 – 290
H. Backe, W. Lauth, P. Kunz, A. Rueda, J. Esberg, K. Kirsebom, L. Lundsgaard Hansen, U.K. I. Uggerhøj
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Positron channeling at the DAφNE BTF facility: The CUP experiment. Charged and Neutral Particles Channeling Phenomena, Channeling 2008, Proceedings of the 51 st Workshop of the INFN ELOISATRON Project, 25 October - 1 November 2008, Erice, Italy, Editors Sultan B. Dabagov & Luigi Palumbo, World Scientific 2010, p. 319 – 330
L. Quintieri, B. Buonomo, S.B. Dabagov, G. Mazitell, P. Valente, H. Backe, P. Kunz, W. Lauth
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Future aspects of X-ray emission from crystal undulators at channeling of positrons. Il Nuovo Cimento 34 C, 175-180 (2011)
H. Backe, D. Krambrich, W. Lauth, B. Buonomo, S. B. Dabagov, G. Mazzitelli, L. Quintieri, J. Lundsgaard Hansen, U. I. Uggerhøj, B. Azadegan, A. Dizdar, W. Wagner
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X-ray emission from a crystal undulator - Experimental results at channeling of electrons. Il Nuovo Cimento 34 C, 157-165 (2011)
H. Backe, D. Krambrich, W. Lauth, J. Lundsgaard Hansen,U. I. Uggerhøj
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Channeling and Radiation of Electrons in Silicon Single Crystals and Si1-xGex Crystalline Undulators. Journal of Physics: Conference Series 438, 012017 (2013)
H. Backe, D. Krambrich, W. Lauth, K.K. Andersen, J. Lundsgaard Hansen, Ulrik I. Uggerhøj
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Radiation Emission at Channeling of Electrons in a Strained Layer Si1-xGex Undulator Crystal. Nuclear Instruments and Methods in Physics Research B 309, 37–44 (2013)
H. Backe, D. Krambrich, W. Lauth, K.K. Andersen, J. Lundsgaard Hansen, Ulrik I. Uggerhøj
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Experimental Realization of a New Type of Crystalline Undulator. Physical Review Letters 112, 254801 (2014)
Tobias N. Wistisen, Kristoffer K. Andersen, Serdar Yilmaz, Rune Mikkelsen, John Lundsgaard Hansen, Ulrik I. Uggerhøj, Werner Lauth, and Hartmut Backe
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Steering of a Sub-GeV Electron Beam through Planar Channeling Enhanced by Rechanneling. Physical Review Letters 112, 135503 (2014)
A. Mazzolari, E. Bagli, L. Bandiera, V. Guidi, H. Backe, W. Lauth, V. Tikhomirov, A. Berra, D. Lietti, M. Prest, E. Vallazza, and D. De Salvador
