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User name brads
Log entry time 11:31:09 on October 4,2009
Entry number 293071
keyword=FADC Moller test run commentsI took data in parallel with Sasha and worked on debugging the FADC system under beam conditions.
There are quite a few "DMA transfer terminated by word count 0x 7d0" errors (the 0x7d0 is a hardcoded limit that should not be reached in correct operation). I didn't see these with even high-rate pulser-driven tests, so something interesting is happening.
There are good data coming in though. The snapshots below shows FADC signal traces for each of the 16 FADC inputs for the second and third FADC digitization interrupts for Run 139. Channels 4--7 (row 2) and 12--15 (row 4) are the calorimeter blocks. Rows 1, 3 are for the aperture counters (scintillators). Those are not plugged in right now because it would mean modifying the existing Moller config (which we do not want to do).
The x-axis is 'sample number' (each sample is 4ns). The blue is a profile averaged over N FADC triggers. The green line is a running estimate of the DC bias on the input. the red lines are the signals present for this particular event.
FIGURE 1
FIGURE 2
