Users guide

All information for users can be found in the user guide webpages applicable for all beamlines.

Useful programs for data processing

Powder diffraction data can be integrated using FIT2D or DIOPTAS.

Integration of single-crystal data can be performed with CrysAlisPro.

Useful commands on the beamline

align Moves the diode into position between the DAC and detector, enabling graphing of Intensity in SPEC

dscan ceny -1 1 40 0.1 Translation of the sample stage horizontally from -1 to +1 with 40 points at 0.1 seconds

dscan dacz -1 1 40 0.1 Translation of the sample stage vertically from -1 to +1 with 40 points at 0.1 seconds

cen Moves to the center of a peak of the previous scan

peak Moves to the maximum of the previous scan

umv [motor] [value] Moves the motor to a given value

umvr [motor] [relative value] Applies a relative move to the motor

tw [motor] [relative value] Applies a relative move to the motor repetitively

cendac 0.25 5 0.1 Corrects for the DAC’s center of rotation (0.25 is the width of the scan for ceny, 5 degrees each way for 0.1s). Should correct up to 25 degrees rotation for single crystal diffraction and up to 10 for powder.

dscan cleanv -0.1 0.1 40 0.1 Scans the pinhole in the vertical direction for alignment

dscan cleanh -0.1 0.1 40 0.1 Scans the pinhole in the horizontal direction for alignment

ruby Moves the ruby stage into place for viewing the gasket hole and measuring the ruby.

beam Moves the ruby stage out

pm prepare measurement: closes the fast shutter and moves the diode out of the beam path.

oscillation Command to start a data collection: change the angle range, oscillation range, exposure time (always 1s for step scans), basename, and Image number. ‘c’ is used to start the data collection.

Collect a wide image for inspection of the crystal quality and intensities: from -20 to 20, oscillation 40, exposure time 2s. Using Fit2D or Dioptas work out the number of overexposed peaks using the equation:

Exposure limit = 300000*(Oscillation_step/time_step)/(oscillation_wide/time_wide)

e.g. Exposure limit = 300000*(0.5/1)/(40/2) = 7500.

All peaks above 7500 in the wide image scan could be overexposed in the step scans (0.5deg/1s).

umv IVU20c 17 Changes the gap in the undulator to vary the beam intensity. Lowest value is 7.1 (most intense beam) and highest is 30 (least intense beam). Usual to operate at a value of around 15. When changing the gap, type align beforehand to check how the intensity measured by the diode changes.

wa Gives the positions of all the motors.

mv dacrot 20 Rotates the sample stage by 20 degrees. Should be used to check there will be no collisions or entanglements when first placing the DAC.

wm ceny dacz Gives the positions of motors ceny and dacz

mempos Memorises the ceny and dacz motors. Can memorise up to 5 positions (mempos1, mempos2…)

gopos Moves to the ceny and dacz positions memorised

Increasing membrane pressure

Use the pace terminal to control the membrane pressure (make note which controller was connected to the DAC (pace 1 or pace 2). Check there is no leak after connection by putting 10 bars and then pressing ‘measure’.

umvr pace 1 Relative increase of the membrane controller 1 by 1 bar.

umvr pace2 1 Relative increase of the membrane controller 2 by 1 bar.   

Troubleshooting

SpecPLOT disappears: type crtl D in the exp window, this will close spec. Type exp in the exp window and run a standard dscan for the windows to reappear. May need to also restart spec on the computer in the hutch: type exp in the exp window.

Zaber console crashes: close the window and restart it. Choose COM1 as the device to connect. Change the units to mm for motors. Then make a small movement for each of the motors (0.01 moves) to see the absolute values of the microscope.

Error value out of range when measuring ruby: the beam is too intense and saturates, so either reduce the acquisition time, move slightly off the ruby, or reduce the laser power by typing umv la 0.64 in the exp window. Check first the value of la before changing it by typing wa. Lower values reduce the intensity of the beam, while higher values increase it.

PRL system crashes: Restart the PRL program. Need to do the calibration after restart. Place the light into the PRL system and press calibrate, should have three main peaks. Take away the light source and continue as before.

Oscillation macro crashes: if a letter or a very small number is typed into the oscillation range, then the macro crashes. Type:

P OSC_DATA[“step”]

P OSC_DATA[“range”]

To check the values recorded and

Osc_DATA[“step”] = 1

Osc_DATA[“range”]=1

to restore its functionality.

Beam loss: Check the IVU20c gap after a beam loss as sometimes it can be changed to higher values. Check that the front end is open.

No diffraction: Check that the pinhole is correctly centered (especially after moving/changing the cell). Check that the front end is open (especially after a beam loss). If not, open FE and start auto.

Also find the wiki link with more details.