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June 18, 2015 Drift Chamber meeting


  1. Instructions for Bluejeans meeting connection
  2. Meeting ID: 290664653
  3. To join via a Web Browser, go to the page [1] https://bluejeans.com/290664653.


  1. CDC analysis update (Beni, Simon)
  2. FDC analysis update (Lubomir)
  3. Electronics
  4. Engineering
    • Power outage
  5. Other


Participants: Naomi (CMU), Sean (NU), Fernando, Beni, Luke, Dave, Chris, Nick, Simon, and Lubomir (JLab).

FDC update

- Lubomir studied the effect of the centroid reconstruction on the systematics in the residuals varying with wire position(x). The point is that the wire position w.r.t. rhombus defined by two crossing strips varies slowly along x. The period of these variations is the same as the one observed in the residuals. For these studies we used 55Fe data with FDC4 in the Hall.

- First three plots: total charge spectrum with Ar peak of 8-9% and the second (escape?) peak not well defined; shape of the signal (integral/max) as a function of the total charge; up/down charge ratio vs total charge. One can see the signals get much wider at the second peak. The two bends in the up/down ratio correspond to +/-125 microns - could be the position of the avalanche w.r.t wire.

- Last two plots: the average correction to the strip-reconstructed wire position vs distance from the hit to the middle of the strip (upper) using different methods: centroid vs fit and using max value vs integral. First plot is for signals in the Ar peak, the second plot is for signals in the second peak. One can see significant difference in the corrections depending on the shape of the signal. Certainly, the fit gives better results than the centroid but it's not free of systematics. It's not clear if max values or integrals are better - result depends on signal shape.


- Beni reduced the flow in the CDC from 0.5 to 0.4 l/min, but increased the flow in FDC4 from 0.06 to 0.07 l/m to have it bubbling.

- This morning the power in the Hall was turned off. There are some issues with the third phase of the generators, but the gas system and the magnet will work (Dave). The power is expected to be back on Monday, so by next Wednesday we will be ready to power on.