Updated 10/21/11:

From the meeting this morning it sounds like all the faulty APV chips have been replaced, and there are also enough good signal cables at BNL to replace the bad cables. So all the pedestal measurements should now be good.

Some of the quadrants have been moved, all have been sealed around the connectors and boards with silicone and the gas flow retested. Here is the new information from Ross, summarizing the positions and gas flows (compared to Table 1 farther below):

007 1C  63 (flow down from >60, no bubbles)
008 1B  58 (moved from position 3B, flow down from >60, no bubbles)
009 1D  5 (flow down from 10)
010 6B  27 (moved from position 1B, flow about the same)
011 6A  45 (moved from position 1A, flow about the same)
012 4A  >60, bubbles.  We're going to retest this in the morning (flow down from >60, no bubbles)
013 2B  25 (flow same as before)
015 5B  56 (flow down from >60, no bubbles)
018 5A  25 (moved from position 3A, flow about the same)
019 2A  21 (flow down from >60, no bubbles)
020 4B  60 (wasn't mounted or tested before)
021 1A  57 (moved from position 4B, flow down from >60, no bubbles)
022 3A  13 (wasn't mounted or tested before)
023 3B  30 (wasn't mounted or tested before)

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We've mounted all the FGT quadrants we have onto disks in what will probably be their final positions, and we've conducted a series of tests. (We don't yet have quadrants 22 or 23, and we've saved quadrant 20 to use in cosmic ray tests with the final two expected quadrants.) We've numbered the disks 1-6, where disk 1 is that which will be closest to the interaction point. Looking at the FGT from the disk 1 end, position A is to the left, B on bottom, C to the right and D on top. Every cable has its own customized length, based on its projected position; we've laid out all the cables we have to check that the lengths will work. We've attached the HV cables for which we have quadrants--one cable to each quadrant. The signal cables attach at the edges of the quadrants, so that each signal cable attaches to two quadrants, so we label signal cables DA, AB, BC and CD.

On its outside edge, each quadrant has a long flat section (that contains all the pins) between two circular arcs. The flat section is not centered on the edge, so each quadrant has a long arc and a short arc, and each quadrant has one APV chip board on the long arc side and one on the short arc side. Table 1 below uses these "long" and "short" labels for the HPV chips and signal cable channels. Each signal cable mounts so that signals from the chips on the long-arc side of one quadrant occupy signal channels 0-4, and signals from the chips on the short-arc side of the other quadrant occupy signal channels 5-9--or 0-4 in the "short" columns in Table 1. The signal cable naming scheme is disk/short/long.

Table 1: Gas Flow Rates and HV Checks by Quadrant

We remeasured any bad signals using one of the cables from a good-signal measurement, to determine whether the chip or cable produced the bad signal. We also used one of the known good signal positions (3AB) to test the signal cables we couldn't measure in their proper positions because we don't yet have the quadrants (e.g. the disk 6 cables). Cables 1AB, 3DA, 4DA and the second cable labeled 1DA (but actually 2BC) are bad.

Table 1 shows that chip 2 on quadrant 1A short, and chips 1 and 2 of quadrant 2A long are faulty.

I also tested the leakage of the gas lines, by connecting the input hose directly to the output hose. (We store them this way by default.) I turned on the flows and adjusted them so that the lines bubbled about 12 bubbles per 20 seconds. Once I adjusted the flows so that all lines bubbled at about the same rate, I recorded the flow rates (in whatever units the lines on the flow meters indicate).

Table 2: Empty Gas Line Flow Rates for Bubbling at ~12 Bubbles/20s

We've been using lines 1-3 for cosmic ray testing, and lines 4-6 for HV testing.