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November 17, 2016 Drift Chamber meeting


  1. Instructions for Bluejeans meeting connection
  2. Meeting ID: 290664653

Headline text

  1. To join via a Web Browser, go to the page [1] https://bluejeans.com/290664653.


  1. Preparations for the fall 2016 run
  2. Tracking
  3. fADC125 (Naomi, Cody, Beni)
  4. Other


Participants: Curtis, Mike, Naomi (CMU) Sean (NU) Fernando, Eugene, Alexander A., Beni, Chris, Nick, and Lubomir (JLab).

Preparation for the fall 2016 run

- Naomi: in the last days the temperatures in the CDC have drifted from their standard values. Nick prepared a plot attached above demonstrating this. Will discuss it with Tim. The noise in the CDC turned out to be a result of using different triggers - the noise disappeared once Naomi used the correct trigger type (code provided by Beni).

- Naomi showed the effect of the alcohol on the CDC - increased total drift time by a little and increased amplitude (see link).

- Fernando and Lubomir studied the noise in the Hall related to high trigger rates. The noise is seen on the FDC TDCs coming from the input to the discriminators. Scope screen - yellow is the trigger at the SD, pink is the discriminator output. On the spectral analyzer the noise had equidistant peaks - ~3.3 MHz apart for 60 kHz trigger rate and ~10 MHz apart for 15 kHz trigger rate - with an amplitude ~10dB in a wide range of 100MHz. The noise is seen everywhere on the crates and also along the signal cables. Fernando: the noise is low, but maybe combined from all the crates might indues measurable signals on the wires (Lubomir), as is the case. Discussions with Sergey after the meeting - the data rates (due to the noise) on some TDC crates are very high limiting the DAQ performance for the high intensity running.


- Mike reported on his plan for the CDC and FDC alignment (see the link above). On a scale of +/- 250 microns one certainly sees in the FDC residuals some non-uniform features over the area of the chambers. The residuals are from a run with magnetic field and tracking through both CDC and FDC without excluding the corresponding chamber from the track. The plan is to use MILLEPED but before that it requires some good work: fix some issues with the output from the Kalman filter, calculate full co-variance matrix (not only diagonal elements), implement straight line tracking through both CDC and FDC, standardize the geometry and alignment constants.

- Sean discussed a plan to improve the tracking simulations (linked). This includes two steps: update the detector hit objects, then study the performance of reconstructed tracks.


- Next meeting in two weeks