You're faced with the following problem: you've somehow become responsible for bringing the beam to the sample in a simple jet experiment at CXI. This article will go into detail on how to do that.

Know the Dangers:

  1. CSPAD is in danger of being sliced in half by the SC1:VGC02 gate valve. This gate valve will close if there is an MPS trip. To prevent this one must pin the gate valve.
  2. Hitting a gate valve with a focused beam, i.e. SC1:VGC-02 (which is also why it can trip MPS).
  3. Make sure nothing is in the beam path that could produce a strong scattering reflection onto the CSPAD, such as a jet nozzle. Thin YAG screens are okay, given suitable attenuation (noted later).
  4. Take care that the sample manipulator vertical (Y) step is small and that you have tested the polarity of motion before letting the beam into SC1, as this can lead to dangerous reflections (see point #3).

Step-by-step guide

Prior to starting. Beam is coming in 15 minutes.

 

  1. Locate the following screens:
    1. OMS: Offset Mirrors Main: cxihome > XTOD > OMS (bottom right of this complex screen)
      2. This is so we can access our steering mirror M2H FEE.
    2. Also from the OMS screen we want access to the DG2 HFX stopper. You click towards the FEH. It's in the middle of the XRT:
    3. M3H Mirror control, aka M2H XRT mirror: cxihome > other screens > M3H
    4. DG1 PIM Y controls: CXI Home > Right Side.
      2. To insert this, use the drop down menu (shown in out) to YAG position.
    5. Python Viewer for GIGE cameras/ Opals, navigate to CXIDG1Yag1
    6. The vacuum screen: cxihome > click on the green/red bowties at the bottom of the main panel.
    7. Screen grabber (cxihome>tools column>logbook grabber)
  2. Check that your detectors are working: CSPad. Consider a `daq_control restart` if not. Consider also taking a dark by recording 1000 events and then deploying via `daq_control dark <run number>`.
  3. Verify that safety stopper S5 is closed (screen by the door). The stopper is physically located in the middle of the XRT. No risk of beam entering while we do some adjustments now.
  4. Verify that all chambers are under vacuum first, then open all gate valves up to and including SC1:VGC02, except VGC02 in the KB2 section (it has a diamond window) and is password protected anyhow.
    1. Note; upon opening SC1:VGC02 you should pin the gate valve immediately.
  5. Set CXI's attenuators (in the cxihome front screen) to 1E-1 (10% transmission).
  6. Make sure HFX DG2 stopper is closed (it should be)
  7. Run Alex Batyuk's "Are We Ready" script via `awr cxi`. This will inform you of potential beam blocking items. Note them and figure out what screens you will need (in addition and if any to the ones already called out), but do not yet act.
    1. This should catch a lot of the idiot problems (and some of the corner cases too). No reason not to do this.

Wait for beam. If you're cool, you're watching the ACR Slack channel. Or you can wait for a bell-shaped curve in the beam monitor (indicating they're tuning the energy). Or you can just wait for a call. Once they call they will tell you that you can manipulate the beam. Now we begin.

  1. If MEC was running, you will likely need to move M3H, aka M2H XRT, out. The out position is 18.5 (at least 18.1) on the X-gantry.
  2. Once MEC mirror is out, you're free to open the HFX DG2 shutter if you've satisfied all of the notifications awr raised.
  3. Open the pulse picker.
  4. Insert the pop in monitor (PIM) YAG for DG1 (by moving the motor to 0) and look at the python view. You should hopefully see a hint of beam. If yes, we proceed. If no, consult the debugging steps below.
  5. Use M2H FEE mirror (from the OMS panel opened earlier) to steer the beam left and right. Steps of 0.5 urad is big, 0.1 urad is small. Left is +, Right is -.
    1. If the beam vertical has to be changed, then we need to call ACR and request repointing. 20 um is a small ~1/4 screen move. 50 um is a larger ~1/2 screen width move.
  6. If we are multiplexing with XPP or XCS, then they will want to insert their diamond window to pick off a portion of the beam. This will add wrinkles to the beam in your DG1 view.
    1. Call XCS or XPP and get them to reposition the diamond window if wrinkles are not pushed to the borders of your DG1 view. You won't get rid of them, but you can move them to the sides.
  7. Once satisfied, screen grab the DG1 view and note the attenuation in the comment.
    1. Attach to inst. log
  8. Hit F12 to close the pulse picker.
  9. Remove the PIM Yag for DG1. Insert the PIM Yag for DG2 (after KB mirror) and navigate python viewer to CXIDG2Yag1
  10. Set CXI attenuation to 1E-3, then open pulse picker. You should see beam on DG2. That is all we need to do (confirm).
    1. Take a screenshot of DG2 result & attach to inst. log
  11. Hit F12 to close the pulse picker.
  12. Remove DG2 PIM YAG.
  13. Switch to the inline view of the jet (probably a DAQ camera, Opal variety)
  14. insert the "Dangly D", a diode called SC1 LED stick.
  15. Manipulate the stick Z (and possibly X/Y) until the crosshairs overlap the YAG.
    1. Remove the Dangly D.
    2. Turn off the LED
  16. Set CXI attenuation to 1E-3 (should already be there) and Open the pulse picker.
  17. hopefully you will see the beam on the YAG.
    1. Focus on the YAG using fine Z positioning of the stick. If necessary you can use coarse positioning.
    2. Take a screen shot of the YAG, noting the attenuation.

 

Beam is now on the sample. Close the pulse picker. Remove the Dangly-D. Set the fine position of the stick to 0 (as well as coarse position if that was moved). It's now time to break into the hutch and remove our diagnostic stick.

  1. Open the thumb-screw that retains the rod.
  2. Start pulling up the rod, until you can feel a hard stop. Avoid twisting the rod; pull straight up. Close the retaining thumb screw to keep the rod from falling down.
  3. Close the gate valve (red button will be fully receeded).
  4. Close the roughing pump (green ball valve on the shelving above the chamber, to the right as you see the smiley face of the chamber door).
  5. Open the venting valve (black ball valve, near roughing valve).
  6. Close the vent after the venting noise has ceased.
  7. Open the clamp retaining the road, it looks like a make-shift shackle.
  8. Pull out the rod.

 

Now we are ready to collect.

  1. Hit F12
  2. Position jet according to cross-hairs in inline view and cross-hairs in off-axis view using the fine motor controls of the rod.
  3. Move detector to the correct position in Z. Control can be found in DS1 on cxihome (it's a collection of green circles). The motor value is password protected. The usual password.
  4. Attenuate beam to 1E-8 and open fire
  5. Begin ramping up beam intensity on the jet whilst keeping a trigger finger on F12 and monitoring CSPAD for bad times.
  6. Once at target intensity, 1E-1 for LCP, hit F12, record a dark, then open for business.