Geometrical aspects of QENS experiments in case of anisotropic samples
Tóm tắt
Diffusion in anisotropic samples is often studied by
quasi-elastic neutron scattering at time-of-flight (t-o-f)
instruments. During the data analysis the measured dynamic structure
factor S(Q,E) is fitted by a model function, which - reflecting the
anisotropy of the sample - depends on the sample orientation. The
error introduced in this way will be discussed. Correct measurements
can be performed for such cases at a triple axis spectrometer, where
energy scan can be performed for a certain Q vector fixed to the
sample orientation. Clays show 2D anisotropy in the structure, which
is supposed to be visible also in the diffusion of water located
between the clay sheets. A first experiment performed on TASP (SINQ)
will be shown.
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