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November 19, 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 update (Mike, Simon)
  2. FDC update (Lubomir, Luke)
  3. Electronics (Fernando, Chris, Nick)
  4. Engineering (Dave)
  5. templates for CDC and FDC NIM papers
  6. Other


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

CDC update

- Nick found the broken wire and separated it from the HVB (see log entry above). He fixed one more channel by replacing the HVB card.

- Mike is looking now at the beam data; will apply the same correction as with the cosmics to correct for the tube sagging.

FDC update

- Lubomir showed latest results on the resolution studies. The resolutions improved gradually due to some residual corrections, better alignment, tracking and finally by using Mathieson/Simon's function when fitting strip clusters; first plot shows the different functions used. Cathode resolution (second plot): red - resolution along y from tracking; green - after subtracting the tracking contribution (assumed to be about 100 microns); blue - resolution estimated from reconstructing wire position. Need about 80 microns contribution to explain the difference (quadratically) between green and blue - may come from the extension of the avalanche along the wire. Wire resolution (third plot): red -reconstructed from tracking; green - after subtracting the tracking contribution of 100 microns. In summary: cathode resolution (along wires) ~120 microns; wire resolution ~110 microns (between 1 and 4.5 mm from the wire).

- We started preparing a document describing the tests with the spare package.


- Lubomir and Luke finished the response function measurements for both FDC and CDC preamps. First two plots show typical response functions (from fADC125). Third plot: Max/Min absolute values of the response function vs the input charge for both FDC and CDC. The linear range for the CDC is wider than for the FDC (in fADC125 units). Fourth plot: Max/Min ratio is constant for the CDC but goes down with the charge for the FDC. It is not clear why (saturation effects?) but helps to eliminate the ion tails, which is not the case for the CDC.

- Lubomir also used a scope to measure the FDC preamp+cable response function (last plot). The gain is about 1.8mV/fC. When compared with the fADC amplitude it saturates in a different way, not clear why.

CDC/FDC papers

- Beni created templates for the NIM papers.


- Next meeting in two weeks - on December 3.