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HK: Physik der Hadronen und Kerne
HK 4: Instrumentation und Anwendungen I
HK 4.13: Vortrag
Montag, 17. März 2003, 19:00–19:15, C
Investigation of multi–wave x–ray interference phenomena in crystals at the Mainz Microtron MAMI — •A. Sharafutdinov, C. Ay, H. Backe, N. Clawiter, M. El Ghazaly, K.-H. Kaiser, G. Kube, W. Lauth, H. Mannweiler, and T. Weber — Institut für Kernphysik, Universität Mainz, J.-J. Becher Weg 45, 55099 Mainz
In a cubic lattice structure, like that of a silicon single crystal, the
energy of the ⟨nnn⟩–Bragg reflection in backward
direction coincides with the energy of a ⟨hkl⟩ reflection
if the condition h2+k2+l2 = n(h+k+l) is fulfilled. This equation
is satisfied, e.g., for n=3, h=k=1, l=-1, or n=3, h=k=2, l=4. Together
with the cyclic permutations of these solutions seven beams are able to
interfere in backward direction. Multi–wave x–ray interference
phenomena occur which have been studied at MAMI. Parametric x radiation
and diffracted transition radiation have been observed when the 855 MeV
electron beam passes through silicon single crystals of thicknesses
between 50 µm and 525 µm. Angular distributions of (111), (333),
(444), and (555) reflections have been recorded with a 0.3 mm thick
pn–CCD detector of 10x30 mm2 size which was located in 11.5 m
distance from the target. Pronounced interference structures have been
observed in the angular distribution, in particular of the
(333) reflection at photon energy of ℏω = 5.96 keV, which
surprisingly depend on the orientation of the corresponding reciprocal
lattice vector with respect to the crystal surface normal. An overview of
the experimental results will be presented.
Work supported by the DFG under contract BA 1336/1-3