ESTIA

Reduction Workflows

Reduction of McStas Data

estia-mcstas-reduction.ipynb

Advanced reduction of McStas Data

estia-advanced-mcstas-reduction.ipynb

Angles and alignment

ESTIA computes angles in the laboratory x-z plane, with y vertical. The sample is aligned so that the central reflected beam hits the detector centre. After alignment, each sample rotation about y is accompanied by twice that rotation of the detector. Other alignment rotations stay fixed.

The sample mount angle (RawSampleRotation) is measured from laboratory +x towards -z using the mount’s transformed local +x axis projected onto the x-z plane. The sample may be tilted within its mount. Supply SampleRotationOffset to calibrate the angle, for example from a fit to a known critical edge. The corrected SampleRotation is the angle between the central reflected beam and the sample surface. Sample and reference runs can have separate offsets.

The detector reference is its transformed local +z direction. It must point from the sample to the detector centre. divergence_angle measures each outgoing ray’s angle from this direction, positive from laboratory +z towards +x. The reflection angle is theta = divergence_angle + sample_rotation.