[ Identification | Description | Input parameters | Links ]

The GISANS_sample Component

Identification

• Site:
• Author: H. Frielinghaus
• Origin:
• Date: 10.03.2023

Description

Sample for GISANS
The idea of this sample goes back to the real sample studied in the publication https://doi.org/10.1063/1.4723634
This is a sandwich of a sapphire and silicon slab through which the neutrons impinge and the sample in between where the scattering emerges from.
The sample consist of spherical polystyrene colloids in heavy water that form aligned crystallites at the solid-liquid interface,
while in the middle of the volume the crytallites are orientationally averaged in the polar angle that points in the lateral direaction.
The crystallites of the current verision are not highly realistic because they are monoclinic with a 60° angle mimicking a fraction
of a hexagonal structure with hexagonal planes stacked in the z-direction.
Inside the routine one can change between 2 or 3 different planes. Also the total crystallite size can be changed.
Especially the parallelogram with 60° angle is unrealistic because one usually would assume the crystallites to have a hexagonal shape.
However, the finite crystallites mimic the final correlation length inside the sample.
The sample works for neutrons impingin from the sapphire, the silicon at grazing angles and in transmission in the sense of a SANS sample.
If the neutrons impinge through the other layers (sample and silicon oxide) - the responses are not so realistic and need further development.
Also multiple scattering would be needed to be implemented still - but could be done.

What this sample component covers relatively well is the fact that damping of the intensity by scattering and absorption is also covered.
That means that even at larger angles than the critical angle the intensity is damped inside the sample and so only a certain near surface
layer scatters neutrons.
This effect is not covered by BornAgain.

I see this as a start for further developments.

Input parameters

Links

• Source code for GISANS_sample.comp.

[ Identification | Description | Input parameters | Links ]