As agreed, before starting we called Valerio who made adjustments to the WI suspension control loops .
4 Si-wafers have been placed inside the tower at the ususal positions on the floor (WI-N, WI-S, WI-W, WI-E) just before the bottom flange closing.
the parameters of the venting process were as follows:
- no air dryer (against potential electrostatic effects)
- prolonged stage at low flux, up to about 250 mbar
- normal 2nd stage (nylon pipe upstream length= 3 m , dia = 6 mm)
- manual adjustment from 950 mbar to 1010 mbar
3 + 2 Si-wafers were present inside the tower, installed during the previous intervention. They have been retrieved as first operation (just before activating the clean air flushing).
We quickly checked two of these (Wl-S, WI-N) , observing along one diameter with a 250X microscope, and they appear clean (few or no particles > 10 um). A quantitative analysis will follow.
