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Struktur und Dynamik Poster: Mi., 14:00–16:30 M-P142
Anomalous neutron Compton scattering: convolution approximation vs.
model-free approach
Maciej Krzystyniak 1 , Tyno Abdul-Redah 1 , Aris Chatzidimitriou-Dreismann 1
1 Technische Universität Berlin, Institut für Chemie, Sekr. C2, Straße des 17. Juni 135,
10623 Berlin
A shortfall of the scattering intensity from protons has been observed in liquids (water,
benzene, etc.) and solids (metal hydrogen systems, organic polymers, etc) using
neutron Compton scattering (NCS). However, the conventional NCS data reduction
scheme [1], used to obtain the scattering intensities, based on the convolution approximation
(CA) of the nuclear momentum distribution with the instrument resolution
function was severely criticized. It was claimed that it is the way the energy resolution
function is incorporated in the data reduction scheme that leads to an underestimation
of the scattering intensity. In the present work the CA approximation is compared to a
newly proposed model-free approach that is independent of the form of the momentum
distribution and the resolution function [2 - 4]. The new data reduction scheme is
shown to lead to the same results as for the experimental data published earlier and
treated with the CA approximation thus refuting the criticisms claiming the way the
data reduction is performed responsible for the effect under consideration.
[1] J. Mayers, T. Abdul-Redah, J. Phys: Condens. Matter 16, 4811 (2004)
[2] B.Dorner, Journal of Neutron Research 13, 267 (2005)
[3] M. Krzystyniak and C. A. Chatzidimitriou-Dreismann, Phys. Rev. B 72, 174117
(2005)
[4] M. Krzystyniak and C. A. Chatzidimitriou-Dreismann, Journal of Neutron Research,
in press