• MOVE THE DETECTOR BACK ~20mm FIRST, THEN, MOVE THE GAS CELL DOWNSTREAM AT LEAST 5 mm PRIOR TO MOVING THE PINHOLE OUT OF POSITION AT -50 mm
  • Turn OFF both the X-ray and UV before moving any motors. We once damaged twice the pinhole in one beam time!!!

For gas phase experiments, we have ~20-30 um X-ray, and ~50 um laser beam size. 

  1. Close DIA 
  2. Close the laser shutter
  3. Move DG1 and DG2 YAG out (if they are still in)
  4. Move JungFrau detector downstream 20mm (to protect JungFrau from gas cell)
  5. Move gas cell Z downstream 4.8mm (that’s the length difference between YAG surface and the pinhole surface in the gas cell), if we want the center, 6mm is the value to go (the gas cell has 2.4mm depth, so that’s another 1.2mm from the surface to the center)
  6. Move gas cell X to frosted YAG position (170 → 175mm)
  7. Move pinhole out (-50mm is the out position, ~-27mm is the in position) (pinhole is in the way of observation, need to move it out to see the following gas cell and pinhole image via sc1navitar camera using a long working distance microscope). We should always move the pinhole the last step to avoid colliding with the gas cell.
  8. Reduce X-ray pulse energy and laser pulse energy so that neither saturates the YAG
  9. Block the pump laser: Laser → Laser Control → ATM shutter (CXI:LAS:SHT:03) IN
  10. Open DIA to see X-ray on the YAG, set marker positions
  11. Close DIA, unblock the pump laser: ATM shutter OUT, optimize the spatial overlap by referring to the X-ray markers using the holely mirror’s pitch (CXI:LAS:PIC:03) for the vertical alignment and yaw (CXI:LAS:PIC:02) for the horizontal alignment. 
  12. Once the spatial overlap is good, we follow the reverse steps to move things back to move the pinhole, the gas cell and JungFrau detector back to the data taking positions:
    1. Move pinhole back (X)
    2. Move gas cell back (X and Z)
    3. Move JungFrau back (Z)