I took a Met One GT-521S laser particle counter into BSC2 to answer a few questions.
Q: What is the reading while standing still in the chamber? About zero
Q: How much dust will be suspended by reconnection of BS cables on the inside feedthroughs of BSC2? A: I simulated reconnection of cables by tapping and wiping continuously in one of the nozzles for a minute and the 0.3um size value averaged about 200 particles/ cubic foot while the 0.5um size value averaged about 70 particles/ cubic foot.
Q: What are the levels for walking around (gently) on the aluminum floor of BSC2? A: 0.3 um - about 150, B: 0.5 um - about 80
Q: Does bumping the cloth cover over the top of the chamber increase dust levels? A: Less than walking on the floor
Q: What level is reached while wiping the floor? A: About the same as for walking on the floor.
Q: How long before the dust levels are difficult to distinguish from zero? A: For all of the above experiments, the readings were back to about zero after a minute or so.
Note for the casual reader regarding motivation of this line of alog: I asked Robert to re-invent some of the contamination control metric checks he had done years ago since we have newer staff which maybe have not seen alot of his past good work on dust mobility in chambers. Now is a good time to evaluate and clean an "empty" chamber since BSC2 detector hardware is currently gutted and in the West Bay. We observed oxidation somewhere around the feedthrus in BSC2, or possibly on the support tubes so wanted Roberts keen eye to give us guidance on things like "how bad is it and will it move with XX activity".