[LukeW and RickS]

For the main input beam, we have assumed the center conflat flange is centered laterally in the HAM 1 door.

Yesterday, while checking the beam path between the IO periscope on the PSL/IO table, we found that the 10" conflat flange on the HAM 1 door is shifted to the left (when viewed from outside the chamber) by about a half an inch.

This impacts the performance of the shutter and beam dump that mounts to the input window housing - too much lateral offset and the beams might miss the silicon carbide dump.

We hoped that we might find another HAM door on which the conflat flange centering would be better.

Here is what we found for the positions of the center conflat flange relative to the HAM door (and HAM chamber flange) centerline (tolerances +,- 1/16"):

HAM1 9/16" to the left
HAM6 9/16" to the left
HAM7 5/16" to the left
HAM12 9/32" to the left

Replacing the HAM1 door with either the HAM7 or HAM12 door would get us 1/4" or so, but not likely enough to be worth the effort.

We will look for other options to better direct the beam through the various apertures.