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July 2, 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 (Mike, Simon)File:MillepedeResults 2July2015.pdf
  2. FDC analysis update (Lubomir)
  3. Electronics (Fernando, Chris, Nick)
  4. Engineering
  5. Other


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

FDC update

- Lubomir presented two slides summarizing the FDC performance for the S&T Review. Comments about efficiency slide - the worst (package #3) is shown; each chamber reconstructs 3D hit which requires hits in both cathodes (with at least 3 strips fired) and the wire plane. Resolution - to show the average wire resolution; discussions about why two methods give different results for the cathode resolution and what is the effect of the multiple scattering. General remark - needs bigger axis labels.

- Results with 55Fe source for the avalanche position w.r.t. wire reconstructed from the cathodes. Z (perp. to chamber plane) coordinate calculated from the up/down total charge ratio. X coordinate (in plane perp. to wire) from the crossing of the up/down centroids. After applying centroid corrections and calibrating the channels one can see a hole for the wire and amazing resolution of ~80 microns in X and ~30 microns in Z. Interestingly the avalanche develops at ~130 microns from the wire, while on the drift chamber books it should be below 60 microns.

- Luke and Lubomir are setting up the spare package in the tagger to scan it with 55Fe source.

CDC update

- Mike on the CDC alignment with Millepede: using Monte Carlo he is varying the regularization parameter (that enters as an additional diagonal term) and looking how well the initial offsets are reconstructed. The attached slides above show the results, each slide for a different parameter value. When increasing the regularization term, there's a region where the offsets are best reproduced but then the diagonal term starts dominating forcing all the offsets to be zero.


- No problems reported as a result of the power outage, however most of the equipment is not turned yet on.