Difference between revisions of "Minutes-6-16-2016"

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#* FDC update
 
#* FDC update
 
#** [http://www.jlab.org/Hall-D/detector/fdc/aaustreg/FDC_Performance.pdf Efficiencies and resolution studies] (Alex  A.)
 
#** [http://www.jlab.org/Hall-D/detector/fdc/aaustreg/FDC_Performance.pdf Efficiencies and resolution studies] (Alex  A.)
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#** Charge vs Drift time (Lubomir)
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#** [http://www.jlab.org/Hall-D/detector/fdc/spring2016run/charge_vs_dt_comp.pdf Charge vs Drift time] [http://www.jlab.org/Hall-D/detector/fdc/spring2016run/eff_vs_drift_distance_FDC3.pdf FDC3 Efficiency vs drift distance ] (Lubomir)
 
# NIM Papers
 
# NIM Papers
 
#* svn ls https://halldsvn.jlab.org/repos/trunk/publications/GlueXCDC
 
#* svn ls https://halldsvn.jlab.org/repos/trunk/publications/GlueXCDC
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# fADC125 meeting (Naomi, Cody, Beni)
 
# fADC125 meeting (Naomi, Cody, Beni)
 
# Other
 
# Other
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<!--
 
  
 
= Minutes =
 
= Minutes =
  
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Participants: Curtis, Naomi (CMU) Beni, Luke, Cody, Alexander A., Elton, Vlad, Sergey, and Lubomir (JLab).
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Participants: Sean (NU), Naomi, Mike (CMU) Luke, Cody, Alexander A., Simon, Nick, Chris, and Lubomir (JLab).
  
 
== CDC ==
 
== CDC ==
  
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- 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.
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- Naomi is working on the gains: the phi-dependent gain variations are not correlated with the tube deformations. Mike is working on the time to distance calibration.  
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+
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- 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).  
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 +
- Nick: on the top HVB that had issues over the last run he found some magnetic debris.
 +
 
== FDC ==
 
== FDC ==
  
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- 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.
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- Alex showed a presentation (linked above) about his studies of the FDC efficiency and resolution using higher level (DFDCHit) objects for runs with magnetic field. For these studies he applied some requirements for the track quality, like p>0.4GeV and more than 4 hits per package. The efficiencies look similar to the one with straight tracks, while the resolutions are worse. The cathode resolutions after taking out the magnetic field effects are about 300-350 microns. The FDC timing information is not used, so the residual distributions in direction perpendicular to the wires are almost flat.
  
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- 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).  
+
- Lubomir presented plots showing drop (of about 30-40%) of the average charge with the drift time, probably due to some contamination. Comparison of the results for the runs since 2014 (first plot) doesn't show deterioration in the FDC performance. Correspondingly, the efficiencies (second plot) for drift distances > 4 mm drop sharply down to ~50% at 5 mm, however it corresponds to about 5% average drop. As we measured the Oxygen contamination to be < 50ppm, there must be something else in the gas.  
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+
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- 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.  
+
  
 
== fADC125 ==
 
== fADC125 ==
  
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- Naomi attached above minutes from the last Friday's meeting on implementing the busy signal for f125. ...
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- Cody: no timing measurements yet, needed for the busy signals.
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+
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- 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.
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+
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- ...
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== Discussions about the format of the meeting ==
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- Everybody agrees we don't need this meeting every week, so we will have it every other week.
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- 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.
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+
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- Sergey: it's better for him to get all the information about the tracking/drift chambers related issues within one meeting.
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- Next meeting in four weeks from now on June 16 (Lubomir is in vacation beginning of June).
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-->
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Latest revision as of 16:33, 24 June 2016

June 16, 2016 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. Detector updates
  2. NIM Papers
  3. fADC125 meeting (Naomi, Cody, Beni)
  4. Other

Minutes

Participants: Sean (NU), Naomi, Mike (CMU) Luke, Cody, Alexander A., Simon, Nick, Chris, and Lubomir (JLab).

CDC

- Naomi is working on the gains: the phi-dependent gain variations are not correlated with the tube deformations. Mike is working on the time to distance calibration.

- Nick: on the top HVB that had issues over the last run he found some magnetic debris.

FDC

- Alex showed a presentation (linked above) about his studies of the FDC efficiency and resolution using higher level (DFDCHit) objects for runs with magnetic field. For these studies he applied some requirements for the track quality, like p>0.4GeV and more than 4 hits per package. The efficiencies look similar to the one with straight tracks, while the resolutions are worse. The cathode resolutions after taking out the magnetic field effects are about 300-350 microns. The FDC timing information is not used, so the residual distributions in direction perpendicular to the wires are almost flat.

- Lubomir presented plots showing drop (of about 30-40%) of the average charge with the drift time, probably due to some contamination. Comparison of the results for the runs since 2014 (first plot) doesn't show deterioration in the FDC performance. Correspondingly, the efficiencies (second plot) for drift distances > 4 mm drop sharply down to ~50% at 5 mm, however it corresponds to about 5% average drop. As we measured the Oxygen contamination to be < 50ppm, there must be something else in the gas.

fADC125

- Cody: no timing measurements yet, needed for the busy signals.

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