Difference between revisions of "Meeting-3-22-2018"

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Participants: Naomi (CMU) Eugene, Beni, Alex B., Simon, Alex A., Thomas, and Lubomir (JLab).
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Participants: Naomi (CMU) Sean(FSU), Eugene, Beni, Simon, Alex A., Thomas, Sergey, and Lubomir (JLab).
  
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= Current analysis/issues  =
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= CDC settings for the rest of the run =
  
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- Naomi analyzed the runs from the CDC threshold scan (presentation attached). The number of hits certainly depends on the threshold, mostly pronounced between 90 and 110 (f125 units). The percentage of hits that participate in the tracks (about 30% ) also goes down with the threshold, however this change is relatively small in the 90-140 threshold range.
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Beni summarized the information related to the CDC thresholds from the hardware threshold scans and his software threshold scan.  
  
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- The interesting feature Naomi found is that there's a class of events with low amplitudes with a peak in time that is 20ns later than the peak in the drift time for the good hits. Some of these hits end up as part of the tracks, especially at low thresholds, and their theta/z distributions look similar to the ones of the good hits. We had long discussions about the origin of these hits without any conclusion: cross-talk, some kind of e.m.background, electronic noise, reflection at the open end of the straw ... Important is to look at the wave forms of these events (Eugene). Pure electronic noise we can study on the channels that are disconnected from the straws. To study the electronic noise we are also going to take data with the pulser (random trigger).
 
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- Lubomir measured the Oxygen contamination in the CDC with the two sensors both showing very small values, however the sensors need calibration. Also the sniffer showed some higher levels of Ar/CO2 at the sides of the magnet. At the end most likely the sniffer was damaged by the magnetic field so Beni could not use it today.
 
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- Lubomir showed some CDC events from the raw mode run, that were shown before by Sergey, just adding info about the drift time in the x/y plots (attached).
 
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- Not directly related to the tracking: we discussed the 30 J/psi events that are missing in the newest analysis; Thomas finds also 20-50% reduction of the phi's in v7 (and v11) of the the 2016 data analysis, compared to v6. Alex is going to relax the cuts to try to reconcile v6 and v7.
 
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- We were kicked out of the room by the next gluex meeting.
 
  
 
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Revision as of 18:43, 23 March 2018

March 22, 2018 Drift Chamber meeting

Connection

  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.

Agenda

  1. CDC settings for the rest of the run
    1. Results from the CDC threshold scan run 41611 to 41614 (CDC hardware threshold 90, 110, 120, 140)
      1. normalized rho yields at TH=120 increase by 4.3%, at TH=140 increase by 5.8%. Since these are different runs the data was normalized to the PS-flux
      2. the rho yields seem to scale linearly with CDC hardware threshold.
      3. CDC software threshold scan using run 41611 with hardware threshold at 90. First 3 files of the run are analyzed, same data so no normalization necessary. At 110 a rho yield increase of 3.3% is seen, at 140 a rho yield increase of 3.7% is seen, at 150 a rho yield increase of 3.4% is seen, at 160 a rho yield increase of 2.7% is seen.
      4. the rho yields do not scale linearly with software threshold! They saturate at about 140 (same as the highest hardware threshold)
      5. the software threshold of 140 leads to a rho yield increase of 3.7% while the hardware threshold of 140 to about 5.8%, this may be an indication that there is some shadowing effect.
      6. run 41614 with hardware threshold at 140, an increase of the software threshold from 150 to 160 does not increase the rho yield at a measurable level.
      7. Note that a higher software threshold may lead to lower rho yields before kinematic fitting, however after kinematic fitting more rhos are left! This is particular significant when going from a software threshold of 110 to 140, see logbook entry: https://logbooks.jlab.org/entry/3544993
    2. Impact of the CDC Hit timing cut in the track reconstruction
      1. The increase in rho yield is significant. The cut is set at -60ns to 900ns
      2. The higher the luminosity the higher the impact. At the highest luminosity (Run 41343) the impact was a factor of 2 increase in rho yield.
      3. Similar effects are observed in the omega yields (both decay modes).
    3. Impact of CDC Hit pruning, the removal of hits correlated in time with high amplitude hits that go into saturation on the same preamp card.
      1. A test on run 41343 with and without this pruning results in a increase rho yield of 4.6% when pruning is applied. see also https://logbooks.jlab.org/entry/3543986 and https://logbooks.jlab.org/entry/3543986
  2. Other
    1. Impact of threshold scan on CDC hit efficiency (Alex)
    2. Track matched hit timing in MC: Proton in SC proton in BCAL (Sean)


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