Alignment

This repository is for discussion and recommendations for sample alignment.

Routines for sample alignment typically use:

• the fraction of transmitted direct beam while scanning different motors,
• the position of the specular reflection, or
• a combination thereof.

Literature

literature.md (WIP) contains quotes of publications discussing GISAS sample alignment.

Example: Alignment @MOUSE

As a spark for discussion we used the MOUSE alignment routine which, in its current form, uses the transmission:

Function to fit the incident angle scan: $$T(\theta', \theta_0, l_{\mathrm{sample}}, y_{\mathrm{beam}}, \sigma_{\mathrm{beam}}) = 1 - \frac{1}{2}\mathrm{erf}\left[\dfrac{\dfrac{l_\mathrm{sample}}{2} \cdot |\sin(\theta' - \theta_0)| - {y_{\mathrm{beam}}}}{\sigma_{\mathrm{beam}}}\right]$$