[Halld-tracking-hw] NO FDC meeting tomorrow 03/08, some update below

[Lubomir Pentchev]

Due to the lack of rooms this week and also some key people not available, 
there will be NO FDC meeting tomorrow.

We are doing different tests to figure out the oxygen issue. We put bags 
on the both supply and exhaust manifold and filled them with gas, but 
there was no significant change in the oxygen percentage. At the same time 
we have a testing chamber filled with gas in which we put different 
materials that are used inside the FDC gas volumes and measure the oxygen 
there too. This is to check for possible outgassing. So far no 
materials were found that increase significantly the oxygen percentage.
We are running now with Ar/CO2 90/10 and with this gas mixture at 320ccpm 
gas flow we got very good chamber efficiency (compared to what we had 
before) even the oxygen percentage remains the same, at ~1% level.

On the third package third cell was opened today to clean two noise places 
inside the chamber. The noise was ~10kHz and high amplitude visible on the 
top, bottom strips, and wires crossing these points. We closed the cell 
and tomorrow will continue with the tests. If OK by Friday will install 
the fourth cell.

Bubbler problem solved: Beni demonstrated that at high pressure the 
bubbler stops bubbling but creates gas channel to the air that is not 
visible. Actually Bill proposed to test this long time ago.