Gary T, Danny S, Matt H, Stuart A
Well was a frustrating day today. We removed the 3 wafers (2 horizontal and 1 vertical) and the vertical optic that was still in chamber, and also put in a 1inch optic (still with its first contact). We gave everything a wipe and then vacuumed everything then wiped again.
Keita asked us to centre the BOSEMs on the TMS with the offsets applied and the TMS damped. And so this is what was done. Keita had a look at what we had done and okayed it.
Counts were still really high after vacuuming so we broke for lunch and during that time we got Jim to unlock the ISI. We wiped again and counts okay, so thought we could start the closing process and started with blowing off quickly the TMS. This put the counts up highish, but figured we would try blowing between the two optics for the 5 minutes agreed upon with Mike L and Norna, let counts settle low and then pull FC. Unfortunately we could never get the counts to go lower than say 400-500 (for 0.3um) with people not moving in the chamber for ~30 mins, and as soon as they did the counts would go up into the 900's-1300's (for 0.3um). We tried wiping floor yet again and couldnt get counts lower. Note: we even have a new BSC door cover on.
So I talked to Calum and we decided that we will just have to go with as low as counts as we can get and just log the counts we have whilst doing the closeout tasks. As its getting on today we decided to stop here, Jeff B is going to come in early and wipe the chamber again one more time...this should give time for everything to settle and then we wil ljsut go for broke with pulling this. I dont think we can get this much better in the near term. I think shows how important that we need to do cleaning on the go everytime anyone is in there.. We are very confident we can get everything done in a couple hours after morning meeting tomorrow though and then that end is done.
PS..Gerado just came and talked ot me and the "stuff" we see on the middle viewport of eastern door is on the middle. We we will paint FC on that tomorrow as well and pull that (before we pull FC on optics)
Quick timeline
Particle counts
In cleanroom start of day
All counts zero (see pic 1)
In chamber start of day
All counts zero (see pic2)
In chamber as removing wafers (see pic 3)
0.3um.....950 counts
0.5um....400 counts
0.7um....270 counts
1.0um....200 counts
2.0um..140 counts
5.0um...60 counts
Pic 4....S/N of the optic put into X end station
Pic 5...vacuuming under the floor boards
In chamber during vacuuming (see pic 6)
0.3um....3050 counts
0.5um....1460 counts
0.7um...950 counts
1.0um....650 counts
2.0 um...400 counts
5.0 um....40 counts
In chamber exiting for lunch..to let counts settle (see pic 7)
0.3um....2310 counts
0.5um...1030 counts
0.7um....570 counts
1.0um...340 cunts
2.0um...240 counts
5.0um....60 counts
1.30pm...in cleanroom after lunch
All counts zero
1.32pm..In chamber after lunch (see pic8)
0.3um...80 counts
0.5um...20 counts
rest zero
1:44pm..blowing TMS optics
1:49pm..finished blowing TMSoptics
Particle counts (see pic 9)
0.3um...940 counts
0.5um...400 counts
0.7um...200 counts
1.0um...130 counts
2.0um...70 counts
5.0um..10 counts
1:50pm...blowing between two optics for 5 mins
Pic 10...Gary blowing between optics
Particle counts end of blowing (see pic 11)
0.3um....1020 counts
0.5um...550 counts
0.7um...300 counts
1.0um...220 counts
2.0um....150 counts
5.0 um...20 counts
1.58pm...starting TMS TF;s
2.15pm..counts still in 400-500's for 0,3um range
2.40pm...talked to Calum about Particle counts....Will go with lowest we have seen (400-500 count range) to be our new "zero" for this chamber this time
2.45pm...counts in 0.3um range back to 600-800 range with little to no movement by guys in chamber
2.52pm..wiping floor again
3.17pm particle counts (see pic 12)
0.3um...1300 counts
0.5um....570 counts
0.7um...370 counts
1.0um..240 counts
2.0um...160 counts
5.0um...60 counts
3.30pm..calling it quits
I've mentioned this numerous times, but unfortunately our schedule does not allow for it: The settle time of 0.3-1um dust in chamber is 2-3 hours (see the dust log Justin made a year ago ish). So, what we likely need to do is clean the floor, let it settle 2-3 hours (no traffic), clean the floor, let it settle 2-3 hours (no traffic), repeating the settle and clean steps ~4 times to actually remove the continually stirred up dust. Waiting 30 mins likely will not yield an large improvements in counts unless we can control where it goes.
We have some other experience indicating that this wipe and wait technique works. When we start up a new cleanroom, we often have dirty mops for the first few days as we clean the room and floors numerous times after long settle periods. On the ~5 day, the mops start to look cleaner.
I cannot dispute the 2 hour settling time that you have observed for the LHO BSC's, but all I can say is what I have found and that is that for the closeout of the HAMs here at LHO the last couple weeks (and at LLO before that), I found that the counts would settle on the order of minutes to 10's of minutes if they were high due to something being stired up (ie after people stopped working in the BSC's) ...however i dont recall counts in the thousands in the HAMs, (I also did not find that if someone was working in a HAM chamber that you would see an effect of this work in an adjacent HAM chamber..eg when Hugh working in HAM2 balancing we saw no effect of this when we were in HAM3...similarly with work in HAMs 4 and 5 at the same time). Also I dont recall at LLO it taking 2 hours for counts to settle in the BSC's...but then again I dont recall counts in the thousands either at LLO (maybe it was, I just dont recall it). We (as in the LIGO community) are much more observant now about particle counts and monitoring/logging when work is occurring(if wanted I could try to troll back through LLO alogs to see what numbers we ever saw if/when we reported them). I have been told by various people at LHO today though that this is the "dirtiest" chamber and has had the least amount of cleaning.
What this alog does not show/reflect is that over the course of the last 2 days we have wiped the floor at least 4-5 times, and separated by many hours (ie some yesterday some today) between wipes, which should of given plenty of time for anything stirred up to settle and it seems to have had little effect (I have not posted every wipe down and every particle count ever taken). What has been the problem today (and again not shown entirely in the timeline) has been that we can get the counts to be kinda low (mid hundreds of counts) if everybody stays still for a long period of time but then if someone moves ever so slightly in the X-end chamber it just stirs up the counts into the high hundreds/thousands of counts, so we were hesitant to start pulling first contact under this situation (and then once we couldnt solve this we phoned calum for guidance for going forward). So to me what this shows is further proof that clean as you go cleaning is very very important in trying to clean up the particulate in the chambers (and that others in industry has shown is the way to cut down particulates) and that as a LIGO community we need to be better at doing clean as you go cleaning every time someone is in any of the chambers, and not just trying to clean up at the end as we close out a chamber, even if this is wiping over and over right at the end. What we think is something that we need to try at the X-end is that we need to try is to better saturate the dust on the floor before we wipe it so as not to stir it up when we do try to clean. Vacuuming appears to stir up more particulate in the air than wiping as we observe higher counts when vacuuming than when we do wiping. Again this paragraph is just a statement of what seeing at the X-end BSC.