cheryl.vorvick@LIGO.ORG - posted 16:42, Tuesday 19 February 2013 - last comment - 12:01, Wednesday 27 November 2013(5530)
Inspection in HAM2:
Jodi and I inspected HAM2 withness plates and surfaces, and found a lot of articulate. Wafers also have visible finger prints, that I put there installing them - good reason to use our nifty wafer tweezers. Particulate found on all wafers. Examples include but are not limited to white fibers, black flecks, white flecks, metal flecks, bright red stuff, and a bit of First Contact.
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- Jodi, Cheryl Observations of witness plates and other in-chamber surfaces goes as follows: Every surface we looked at had particulate, including table top, optic structures, etc. Optics, both small fixed 2" and the larger 4" IM2 and IM4, show particulate. Witness Plates: - Worst contamination: One 4" witness plate on the HAM2 table top: Exposed during IO installation, pump down and vent. Significant particulate, and my gloved hand print. - Competing for the next worst contamination: Two 4" witness plates in the beam tube, North and South of HAM2: Exposed during pump down and vent. Large particulate easily seen from about 1.5m away. Two 4" witness plates in the bottom of HAM2: Exposed during pump down and vent. Large particulate easily seen from about 1.5m away. - The winners, showing the least contamination: 4" witness plates in the beam tube, West side of HAM2 on ISI level-0, positioned North, Center, and South: Exposed during pump down and vent. Small particulate easily seen by eye. - The three 1 optics had some particulate but were very hard to evaluate in-chamber, so hard to say how much contamination is on their surfaces until we can pick them up. There was a piece of First Contact, about 1mm square, on one of the 3 optics - it was missed by at least two sets of eyes before pump down. The up-side is that this does show that FC stayed put on an optic during pump down and venting. Current State of Witness Plates in HAM2: We did not have containers to remove wafers or 1" optics, so new wafers were installed along side the old wafers, (in every position, the new wafer is installed in the counter-clockwise direction from the old wafer). Two new wafers replaced the old table top wafer, and the old wafer was moved across the table, to prevent it from contaminating the new wafers.
On Nov 21st, 2013: Calum and I picked up a few witness plates in HAM2 and 3 since we had so many in there. We picked up the 2 that were in the HAM2-HAM1 spool floor, and both that were in front of the PR3. We placed a new one near the center of the table behind PR3.