kaitlin.gushwa@LIGO.ORG - posted 09:20, Thursday 06 February 2014 - last comment - 10:29, Tuesday 11 February 2014(9850)
HAM4 witness plates & optics
Jeff B. & Kate G. A horizontal 4" witness plate (wafer) and horizontal 1" optic (S/N 1247) were placed near the center of the SEI table on Feb 5th. A vertical 1" optic (S/N 1245) was mounted on the HR side of SR2. A vertical wafer still needs to be set near SR2. Important notes: Witness samples were not placed immediately after the chamber was opened. Jeff did some cleaning before SR2 was installed and the wafers and optics were placed. Also, the 1" optics were removed from their PET G containers, put in PEEK holders, double bagged, and stuck in a bag with other tools before going in chamber. I didn't see obvious scratches in the First Contact, so hopefully the samples weren't damaged.
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On Feb 7th, I used a handheld particle counter in the cleanroom around HAM4 and in chamber before starting work. The counts seemed really high. The particle counter (used for trending data) on the +X side of the chamber was not working.
| Size (um) | Cleanroom Count | Chamber Count |
|---|---|---|
| 0.3 | 10725 | 17177 |
| 0.5 | 2518 | 3895 |
| 0.7 | 1075 | 1562 |
| 1.0 | 586 | 798 |
| 2.0 | 169 | 213 |
| 5.0 | 1 | 0 |
I placed a vertical wafer near the HR side of SR2, and inspected the cleanliness of the chamber with a flashlight array. There were a few particles on the witness samples (which had not seen work since they were placed two days earlier), and a lot of contamination on the TCS HWS optics and SEI table. The dark iPhone photos don't do it justice.There was only time for a quick cleaning using the TigerVac and IPA soaked wipes. It would be helpful to get a PET swipe sample the next time work is done in HAM4.
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