Beamline Alignment Quick Reference

Back to X-Ray Microscopy

1) Select x-ray energy:
Calculate scattering angle of Si 111 for desired energy with Bragg law calculator (or approximate Theta ~ asin(1.977084/E keV) )
Drive DCM Theta to the correct Bragg angle for the desired energy, drive undulators approximately to this energy as well

NOTES:
i) If DCM theta looks low for the current energy (~2-4 deg) you may need to re-set user offset (current calibrated theta offset = dial + 8.646deg)
ii) Approximate undulator offsets are ~ desired energy +0.1 keV

2) Scan mirror piezo:
Set slits to

Slit	H Size (mm)	V Size (mm)
PBS	0.2	2
NES	2	2
BDA	2	-

scan mirror piezo +/- 1 V. Set mirror piezo to the maximum.
NOTES:
i) mirror piezo feedback should be OFF
ii) CCD shutter should be set to "manual open"

3) Scan DCM 2nd crystal roll:
Set slits to

Slit	H Size (mm)	V Size (mm)
PBS	0.2	2
NES	0.2	2
BDA	2	-

scan roll +/- 0.15 mrad. Set roll to maximum - correct for backlash.
NOTES:
i) Correct for backlash by driving to first scan point, then to maximum (e.g. after scan drive relative position -0.15, then drive absolute position to max)
ii) Settling time of at least 1 second is necessary for this scan (this axis is UHV picomotor driven in PID)

4) Scan DCM 2nd crystal pitch:
Set slits to

Slit	H Size (mm)	V Size (mm)
PBS	2	2
NES	2	2
BDA	2	-

scan control voltage for DCM piezo tweak +/- 1.5 V. Set piezo to max.
NOTES:
i) if voltage is trending out of range (1V<V<9V), set tweak to 4.5V and scan theta2 motion +/- 0.1mrad

5) Scan Undulators: Scan upstream and downstream undulators +/- 0.25 keV, drive to max
NOTES:
i) Settling time of at least 1 second is necessary for this scan (possibly more)