NOTE: We align everything to DG1 slits.
- Make sure lenses are OUT (if not intentionally left IN for continuous shifts)
- Look at the FEL on DG1_YAG (cxi_dg1_yag_gige camera), use Slits 1 (DG1 Jaws) as reference. Transmission ~0.1 to 0.2.
- If the beam is not centered on the Slits 1 (DG1 Jaws) (or complete off)
- Call ACR for vertical pointing
- Use HOMS mirror pitch (mr2l0_homs_pitch) for horizontal pointing: LFE home button → Mirrors → mr2l0_homs_pitch
- The motor position depends on the photon energy we use
- ~2.2 urad for 10 keV
- ~5.44 urad for 16 keV
- If the beam is not centered on the Slits 1 (DG1 Jaws) (or complete off)
- Bring up and look at the FEL on DG2_YAG (cxi_dg2_yag_gige camera), transmission ~1E-4, move DG1 YAG out
- Close DG1 slits until we see hard edges from the lists, these will be our references for centering the other slits
- Set markers at the four corners of the hard edges
- Check slits 2 (KB1 JawUP) and slits 4 (DG2 Jaws) (skip slit 3, or KB1 JawDown, b/c they are not in use during the gas phase experiments), center them around the FEL
- Set markers on DG2 YAG camera
- Make sure we see hard edges from DG1 slits
- Then center KB1 and DG2 slits to the DG1 slits’ center: open all slits (~2mm), then check slits one by one (~0.3mm) by looking at their hard edges and center them to the reference markers
- Bring up and look at the SC1 YAG (cxi_sc1_inline camera), check slits 5 (DSB Jaws)
- Open all the slits except slits 1 (DG1 Jaws), make sure we see hard edges
- Close slits 1 (DG1 Jaws) even further if needed, set markers at the four corners
- Center slits 5 (DSB Jaws) to the DG1 reference makers
- Check the SC1 Slits mounted on piezo motors. Unlike other slits with centers and widths, we need to move individual motors in order to center the slits around the FEL.
- Insert the prefocus lens, and align the lens (prefocus lens is one lens, not a stack) by looking at DG1_YAG with the lens aperture shadow. Transmission ~0.05 - 0.1 for a clear edge of the lens aperture on DG1 YAG.
- Beamline → Prefocus Lens → Click the button of the right photon energy to move the proper lens
- Use the
Expert
button to get the fine control - The goal is to make the 4 curved corners in the center of the 4 slit blades, ~0.65mm for DG1 slits to see these corners clearly
- Insert the focusing lens stack, and align the lens stack by looking at the DG2_YAG with the lens aperture shadow.
- Insert DG2 YAG and remove DG1 YAG
- We can check again the beam alignment at DG2 YAG, tweak with HOMS or ACR pointing if necessary
- Close DG1 slits to 0.5mm, set transmission 1E-4 to 3E-4 (as low as possible, but need to see clear edges of the slits and lens aperture), insert DG2 lens PACK3 for timing or DG2 lens PACK2 for data taking
- Use the
Expert
button to get the fine control
- Insert DG2 YAG and remove DG1 YAG
- Check FEL go through the director hole and on SSC YAG, transmission up to ~5E-3, move DG2 YAG out
- cxi_sc3_inline camera
- Clear YAG position
- Ap Stand = -9
- PI3 Y = 48.0326 (as of 2022-06-11, this position can change if we changed the YAG padel)
- If no beam on SSC YAG
- Check if pinhole is not out, if so, move it out
- Try moving gas cell X & Y
- Try aligning Questar mirror (b/c sc1_inline mirror may be bumped)
- Once found FEL on SSC YAG, center laser in-coupling mirror X & Y around it
- Perform the gas cell alignment procedure if not done
- With the markers on SC3 YAG (from unfocused beam alignment of the gas cell)
- Close and fine align the DSB slits
- Move until cut, center them
- Close and fine align the SC1 piezo slits
- Move until cut, center them
- Close and fine align the DSB slits
- Make sure we don’t have the outer diffusive beam, one example of slits configuration of data taking mode:
DG1 slits - 0.55, 0.55 mm
- KB1 Up slits - 0.4, 0.4 mm
- DG2 slits - 0.28, 0.28 mm
- DSB slits - 0.08, 0.09 mm
- SC1 piezo slits - 55, 40 um
- NOTE: DG1 slits gap should match pre-focus lens aperture (~0.5mm), and DG2 slits gap should match DG2 lens aperture (~0.3mm)
- If the beam looks not centered on DG2, with all the lens and slits, we should adjust the beam pointing (MR2L0_HOMS_PITCH) or undulator pointing, since our slits and lens are centered to DG1 slits