X23A2 Beamline Evaluation: Energy Resolution

Vanadium pentoxide

Powdered vanadium pentoxide, V₂O₅, was spread onto a piece of kapton tape. Five layers of tape were stacked and affixed to a polycarbonate frame for easy handling. Several scans were measured, all of similar quality. The pre-mono slits were at 1mm and the hutch slits were also at 1mm tall by 5mm wide. The harmonic rejection mirror was in place and set to 0.24 deg.

Other scans gave results within the reported error bars. (Note that this result is about 0.1 volt narrower than APS 20BM.)

The analysis was performed using the script written by Matt Newville to analyze the similar data measured at APS 20BM. Here are the relevant files:

• Ifeffit script

• Athena project file

• Data file used by Ifeffit script

Effect of slits on vanadium pentoxide

I then got curious about the effect of the slit sizes on the energy resolution at this energy. We have slits in the white light before the mono and slits in the hutch before the ion chambers. Below are a sequence of 4 scans with the pre-mono slits set to 1mm and 0.5 mm and the hutch slits set to 1mm, 0.5mm, and 0.1mm. As you can see, the improvement in resolution is, at best, quite subtle.

Copper foil

This is an additional test of resolution that I performed. This is beyond the scope of the APS beamline evaluation protocol.

This is very similar to the slit size experiment on the vanadium pentoxide. Again, this is a sequence of 4 scans with the pre-mono slits set to 1mm and 0.5 mm and the hutch slits set to 1mm, 0.5mm, and 0.1mm. Again, the improvement in resolution is, at best, quite subtle.

Related files

• The Cu data as an Athena project file

Silver foil

This is an additional test of resolution that I performed. This is beyond the scope of the APS beamline evaluation protocol.