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
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 Si 111 Bragg Theta = asin(1.977084/E keV)
iii) 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
NOTES:
i) Correct for backlash by driving to first scan point, then to maximum (e.g. after scan drive relative -0.15, then drive abs 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, check first point)