Slides 23-October-2006

I have some ideas about locating problematic stacks using YMon. I need some feedback about how useful this would be. I want to use distributions of delta-T (the difference between start times in cells with multiple hits) to highlight stacks with oscillations or excessive ringing.

After the meeting some conclusions were reached:

• The odd peak in Δtime starting at about 400 nsec is a real oscillation, which apparently runs at about 2 MHz or less.
• The low peak at O(40 nsec) is not understood, but your obedient servant suspects that it is a property of the signal propagation along the cable, and predicts that this will appear predominantly in pairs of hits where the first has a small width.
• The spikiness observed on plots like those of page 5 is probably due to binning issues (and so it proved to be).
• It was suggested that the low peak might be due to a bad TDC channel, in which case it would not appear in the rest of the layers for that stack.

  West Oscillations

  East Oscillations

  West low peak

  East low peak

  Clearly the West and East oscillations come almost entirely from single cells. However, the "low peak" hits aren't quite so simple. On the West side one stack has all 4 cells contributing heavily, while another has only cells 0 and 3. On the East side a stack has a little from cell 0 but most from cells 2,1, and 3.

Modified 23-October-2006 at 09:51

http://hep.physics.wisc.edu/~jnb/imu/23Oct2006

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