Beam Finder Wire (BFW) Fiducialization

1. Beam Finder Wire (BFW)Fiducialization Zack Wolf, Dean Walters, James Bailey, Eric Lundahl

2. Need For A BFW The undulator will not steer the beam. It will just radiate at the wrong wavelength. The BFW allows this to be detected.

3. BFW Specifications LCLS PRD 1.4-004

4. BFW Operation Out: The beam goes through a small beampipe making a smooth transition to external beampipes In: Wires are inserted into the beamline. The whole girder is moved to scan the wires across the beam.

5. BFW Use Either turn quad off, or use wire system to re-center on beam

6. Fiducialization Accuracy Requirements Rough Error budget: • Locate wire relative to local fiducials (optically): 25 um • 2) Locate local fiducials relative to outside tooling balls (CMM): 15 um • 3) Repeatability of positioning wires: 80 um in X, 30 um in Y LCLS PRD 1.4-004

7. Fiducializing theBeam Finder Wire Dean Walters, James Bailey,

8. Cases to Consider Fiducialization • Case 1 - Initial installation of the BFW • Below is the outline of the Initial Installation followed by the outline of the Replacement of the BFW • Case 2 - Replacement of the BFW • The replacement of the BFW is the more difficult case • Since the case of replacement is constrained access-wise, careful placement of fiducials and the BFW/Vacuum Chamber is important.

9. Case 1 - Initial Fiducializing of the BFW • Step 1 - Wire to BFW Frame Fiducials BFW Frame External Stationary Fiducials (ESF) BFW Alignment Stand External Moving Fiducials (EMF) • On the BFW Alignment Stand the position of each wire can be measured WRT the EMF • Measure the Beam Guide WRT the EMF • With the BFW actuated in each (up & down) position, adjust the stops for each position from the EMF to ESF per nominal dimensions . Beam Guide Wire

10. Case 1 - Initial Fiducializing of the BFW • Step 2 - BFW Frame to vacuum Chamber Alignment • Bolt BFW Frame to Vacuum Chamber and make vacuum seal. • Adjust the lower stops to place the Beam Guide in the center of the Chamber ports. • Then measure the EMF WRT to CSF • Adjust the upper stops to correctly place the wires WRT the Girder Axis (GA) • Then measure the EMF WRT to CSF Chamber Stationary Fiducials (CSF) BFW Chamber Alignment Stand

11. Case 1 - Initial Fiducializing of the BFW • The BFW Chamber along with the BFW is placed in the beam line. • Adjust the Chamber supports to place the upstream port in line with the Undulator Vacuum chamber. • The mating flanges will have the ability to self center to each other. • Make up the vacuum flange seal. • There will be the ability to make fine position adjustments after the seal is made. • Re-measure the placement of the Chamber CSF and the EMF WRT to the GA • Step 3 - Alignment of BFW/Vacuum Chamber to Undulator Vacuum Chamber

12. Case 2 - Replacement of the BFW Beam Finder Wire • Assumptions for replacement of the BFW. • The existing BFW was aligned • The BFW/Vacuum Pump chamber stays in place in the beam line • The BFW/Vacuum Pump Chamber is supported so that when the BFW is removed that it remains accurately in place BFW/Vacuum Pump Chamber

13. Case 2 - Replacement of the BFW • Step 1 – This is the same as Step 1 of the Initial Fiducialization • Step 2 - In the case of replacement the data from Step 2 in the initial case will be used with the new BFW frame. • Step 3 – This is different than the other Step 3 in that the stops will be adjusted in the field using the preexisting data. • This will be more difficult since some lines-of-sight will be blocked due to existing installed equipment. • Access to adjustments will also be more awkward in the field then in Case 1 where the adjustments will be made in the lab. • The new installed assembly will be measured in both positions after all adjustments have been made to record the final placement.

14. How Fiducialization Is Really Done Eric Lundahl

15. Optically Find Wires WRT Local Fiducials

16. Locate ToolingBalls With CMM

17. Previous SLAC Experience