Log entry time 11:11:49 on April 02, 2010

Entry number 315736

Right now,
there is only the UVA chamber in to test the grounding.
The second chambers has a problem, I can only see the last 96 channels of
the chamber, it might be
a short somewhere so it is off.

Signal looks ok, pedestal RMS is around 4 5, there is no pedestal shift
correction implemented yet just the grounding.

The clustering is working for the u1 plane.

Looking at the cluster amplitude, it seems 3750 V gives a good separation
from the pedestal, though one can see the gassiplex saturation around 700
mV, the chip dynamic range is not perfect for this signal polarity and range.

If there is a access around 2 hours, I would like to take the chamber out
to check the electronics, if this is a simple contact somewhere or bad
cable that could be fixed, it could take a bit longer if the electronics
has to be changed. I would also like to put the Italian chambers back in
to check their noise level with improved grounding.
So an additional 1 hour would be needed for that.

I went for max multiplexing of 480 so we have less cables to plug unplug
at the cost of dead time. Since it is not clear if the chamber will have
to go in and out for the rest of the tests I will leave that this way
until we want to optimize and everything works reasonably well.

The chambers can be taken out from the PREX support quickly ( ~20 min in
the hut ) if needed since there is only one pair right now.

Figure 1

Figure 2

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Figure 5