Witness plates, which are 4" diam. silicon wafers, were installed in BSC8 and nearby beam tubes.  The first two attached images show the installation as of Feb. 1, and as installed on Feb. 2.  Locations match, but the second images includes the detail, that may or may not effect the results, that a witness plate was broken and replaced in one location.

Location for witness plates were chosen to give information about migration of particulate from beam tubes to the BSC8 chamber.

Additionally, I chose locations to look at specific areas of interest.
1) both sides of the bellows in the Y arm beam tube (West) and the beam tube that is on the North side of the chamber - (bellows effect on particulate migration)
2) gate valves - in North beam tube and East beam tube - (gate valve effect on particulate)
3) directly under the gap between the ACB and ITMY - (to measure what particulate is falling in front of the optic)
4) directly in the center of the chamber - requested by Jodi for ICC - (to measure overall BSC8 particulate)


I've chosen to aLog witness plate info under LHO, VE, and I've included the specific chamber in the title, i.e.

Title -> "specific chamber"
Section -> LHO
Task -> VE

I've also attached two in-chamber photos of witness plates placed on Feb. 1 - North Beam Tube and East Beam Tube.