Scanning Probe Diffraction Quick Reference
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This reference is intended for general users, notify staff of necessary revisions or to request more detail
Prior to this section it is expected that sample alignment has been performed (Sample Alignment Quick Reference)
All MEDM windows below can be found from the main beamline MEDM screen, to bring up this screen double click the desktop icon "26id MEDM" or type "start_epics" on a terminal screen
To process a new value in any MEDM command field this window MUST be selected (left click or double click) and the mouse MUST remain pointed into that field until the user enters the new value AND hits return
1) Setting up scan parameters
If necessary call up the scan1 and scan2 windows from the main beamline screen (found under SCANS-DCM on the bottom left), then hit the bottom right More button twice on each window
Remove prior positioners by double clicking the drive field until the text is highlighted, backspace, then return
Add a new positioner by middle clicking on the intended motor's command value field, holding the middle button down, dragging to the drive field in the scan window, then release the middle button, left click, then return
Select scanning range by EITHER adjusting the Start and End values OR adjusting the Center and Width values
Select scanning steps by EITHER adjusting the Step Size value OR adjusting the #PTS value on the top right of the window
For additional positioners in a single linear scan (ie to make a theta/two theta scan) click the green Positioners title box, and follow the above steps to modify the fields for positioners 2-4
For a two dimensional scan, follow the above steps to add outer loop positioners and scanning ranges into the scan2 window (do not add any detectors or modify the detector triggers in this window)
NOTES:
i) Make sure the flags below the scan parameter fields are set to LINEAR, RELATIVE, and PRIOR POSITION (to set up other types of scans consult staff)
ii) Make sure the number of active positioners (in parentheses to the right of the green positioners button) is correct, and that additional positioners from previous scans are removed
iii) Make sure the positioner settling time is appropriate for the slowest motor, usually 0.2-0.5 sec - in many cases (soft motors, picomotors, or undulators) this should be at least 1 second
iv) Do not use the "Clear positioners" button, this sets the scan type to "absolute" for all positioners
v) An X next to the drive field should briefly flash if the new positioner is added correctly, and the units field should update to the new motor units
2) Adding detector triggers
Remove unneeded detector triggers by double clicking the pink value field until the text is highlighted, backspace, then return
To activate scaler counters, select 32ch Scaler from the Scalers tab in the bottom right of the main beamline screen, drag the Count button to a DetTrigger field (then left click, return)
To activate fluorescence detectors, select 16-element SDD from the EDS tab in the middle left of the main beamline screen, drag the Erase/Start button to a DetTrigger field (then left click, return)
To activate the CCD detector enter 26id:ccd.AcquireCLBK in a DetTrigger field
Set the acquisition time of all three of these windows to the same value -if the CCD shutter is in use increase the exposure time for the scaler counter and fluorescence detector by ~0.2sec above the CCD exposure time
NOTES:
i) If saving images from the CCD make sure the change directory triggers are in the before scan and after scan placeholders in the scan1 window (consult with staff if these are absent)
ii) If the NPI has thermally equilibrated it's convenient to add 26idcnpi:coarse:allstop to an unused DetTrigger field to ensure no coarse motors are left on
3) Adding detector channels
To bring up an overview of current detector channels click on "DCM scan record detectors" on the NPI tab in the middle left of the main beamline screen
Click on the green Detectors title box immediately below CLIENT WAIT
Remove unneeded detector triggers or detectors by double clicking the pink value field until the text is highlighted, backspace, then return
To activate scaler counters, select 32ch Scaler from the Scalers tab in the bottom right of the main beamline screen, drag the Count button to a DetTrigger field (then left click, return)
To activate fluorescence detectors, select 16-element SDD from the EDS tab in the middle left of the main beamline screen, drag the Erase/Start button to a DetTrigger field
To activate the CCD detector enter 26id:ccd.AcquireCLBK in a DetTrigger field
Set the acquisition time of all three of these windows to the same value -if the CCD shutter is in use increase the exposure time for the scaler counter and fluorescence detector by ~0.2sec above the CCD exposure time
NOTES:
i) If saving images from the CCD make sure the change directory triggers are in the before scan and after scan placeholders in the scan1 window (consult with staff if these are absent)
ii) If the NPI has thermally equilibrated it's convenient to add 26idcnpi:coarse:allstop to an unused DetTrigger field to ensure no coarse motors are left on