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August 13, 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. Detector performance document GlueX-doc-2775
  2. CDC update (Mike, Simon, Beni)
  3. FDC update (Luke,Lubomir)
  4. Electronics (Fernando, Chris, Nick)
  5. Engineering
  6. Other


Participants: Curtis, Naomi, Mike (CMU), Luke, Beni, Dave, Chris, Nick, Simon, Sergey and Lubomir (JLab).

Detector performance document

- Curtis is working on a document describing the so-far achieved detector parameters compared with the design goals. Lubomir will add a page about the FDC.

CDC update

- Simon studied the wire offset as function of z (along wire) using beam data. In the logbook entry linked above, the two plots show the offsets for a straw at 9 o'clock when the track is above/below the wire. The offset variations are consistent with up/down deformation, possibly sagging of the tube or wire. To confirm this, need to look also at straws at 12/6 o'clock. Curtis, Naomi: if supported at the ends only, the tubes will sag by few mm, but after gluing them together there was no sagging.

- Cosmic data will be taken over the weekend with mode 7.


- Nick showed pictures (logbook entry linked above) demonstrating the separation of the CDC broken wire.

FDC update

- Luke reported about the studies with 55Fe source with the spare package (plots attached). One can reconstruct the avalanche position in 2D: using up/down cathode charge ratio for position in direction perpendicular to the chamber and for the left/right position w.r.t. wire using the crossing of the centroid positions on the two cathodes. After fine calibration of the cathode channels one can see a hole where the wire is. Luke fitted the maximums at the two sides of the wire, first, in up/down direction and then left/right from the wire. The up/down maximum positions vary with the charge as demonstrated for two gas mixtures, 60/40 and 40/60 Ar/CO2. The left/right maximums are almost constants. The only explanation so far is related to the contributions from the ion tails that somehow vary with the charge.