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May 19, 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. Detector updates
  2. NIM Papers
  3. fADC125 meeting (Naomi, Cody, Beni) Friday's meeting minutes
  4. Discussions about the format of the meeting


Participants: Curtis, Naomi (CMU) Beni, Luke, Cody, Alexander A., Elton, Vlad, Sergey, and Lubomir (JLab).


- Naomi discussed results, presented at the collaboration meeting by Mike: gain variations vs straw number plot. She cannot explain the fine structure seen on the plot by the straw deformations - the correlation there is not obvious. The assumption so far is that these are temperature/low gas flow effects. To test this Naomi proposed to do cosmic measurements with increased gas flow. Beni will start increasing the flow in the CDC in small steps. We need to coordinate with the DAQ/trigger people when do we want to turn the crates on. Elton: we can turn on and use BCAL as trigger, but have in mind it usually takes several days to get it working.

- Naomi also discussed the "time-walk" correction for the CDC; time is defined as a difference b/n the threshold crossing time and the one from the f125 timing algorithm. The correction is small (1-2 ns), especially if using low threshold, so you don't have to apply it (Curtis).


- Lubomir showed distributions of vertexes reconstructed with FDC using straight tracks: z vs radius, and z vs angle between the two tracks used to find the vertex (see plots above). Requirements for the tracks: going through at least two packages and good chi^2, requirements for the vertexes: DOCA<5mm. One can see that vertexes at the chambers have small angles between the tracks - most likely a result of the multiple scattering.

- Lubomir started working on the data with magnetic field to look at the efficiencies, magnetic field effects etc. The first issue here is the pattern recognition - Lubopmir used conformal mapping as illustrated in two example events. First three plots - classical event with one recoil and two charged tracks in the FDC - easy to reconstruct. Next three plots - event that has not been reconstructed properly, however on the conformal map one sees three lines, corresponding to three circles (tracks).

- Vlad showed his latest results. He used the best hits, centered at the middle of the strips, also simplified the minimization - no resolution improvement so far. Next simplification will be to use data from one wire only.


- Naomi attached above minutes from the last Friday's meeting on implementing the busy signal for f125. ...

- Cody: next week will do measurements (with Sasha and others) of the signal propagation times to the TS crate, as needed for implementing the busy signal.

- ...

Discussions about the format of the meeting

- Everybody agrees we don't need this meeting every week, so we will have it every other week.

- Naomi: before the meeting Lubomir should send an e-mail asking if somebody wants to present something. There was a question if the fADC125 meeting should be part of the online meeting, for now it will stay within the tracking meeting.

- Sergey: it's better for him to get all the information about the tracking/drift chambers related issues within one meeting.

- Next meeting in four weeks from now on June 16 (Lubomir is in vacation beginning of June).