  Grazing incidence fast atom diffraction (GIFAD, or FAD) has developed as a
surface sensitive technique. GIFAD is less sensitive to thermal decoherence but
more demanding in terms of surface coherence, the mean distance between
defects. Such high quality surfaces can be obtained from freshly cleaved
crystals or in a molecular beam epitaxy (MBE) chamber where a GIFAD setup has
been installed allowing in situ operation. Based on recent publications by
Atkinson et al. and Debiossac et al, the paper describes in detail the basic
steps needed to measure the relative intensities of the diffraction spots. Care
is taken to outline the underlying physical assumptions.
