Difference between revisions of "Minutes-7-2-2015"

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= Minutes =
 
= Minutes =
  
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Participants: Mike, Naomi(CMU), Sean(NU), Eugene, Luke, Chris, Nick, Simon, Beni, and Lubomir (JLab).
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Participants: Curtis, Mike(CMU), Sean(NU), Eugene, Luke, Dave, Chris, Nick, Simon, Beni, Sergey, and Lubomir (JLab).
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== FDC update ==
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- Lubomir presented two slides summarizing the FDC performance for the S&T Review. Comments about efficiency slide - the worst (package #3) is shown; each chamber reconstructs 3D hit which requires hits in both cathodes (with at least 3 strips fired) and the wire plane. Resolution - to show the average wire resolution; discussions about why two methods give different results for the cathode resolution and what is the effect of the multiple scattering. General remark - needs bigger axis labels.
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- Results with 55Fe source for the avalanche position w.r.t. wire reconstructed from the cathodes. Z (perp. to chamber plane) coordinate calculated from the up/down total charge ratio. X coordinate (in plane perp. to wire) from the crossing of the up/down centroids. After applying centroid corrections and calibrating the channels one can see a hole for the wire and amazing resolution of ~80 microns in X and ~30 microns in Z. Interestingly the avalanche develops at ~130 microns from the wire, while on the drift chamber books one can find values of ~60 microns.     
  
 
== CDC update ==
 
== CDC update ==
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- Beni looked at the pedestals in the CDC varying different parameters: number of samples used, integer vs real number averaging, position of the pedestal window - all this explained in the above link. The main discussion was about the fact that Beni sees some slope (increase), when averaging over all the events, in the region before the real detector signal comes in case the signals are late. Mike suggested this may come from cross-talk from the other channels, but Beni has looked at this. Late signals can happen in cosmic showers (Eugene). Beni will do more studies when the computers are back.
 
- Beni looked at the pedestals in the CDC varying different parameters: number of samples used, integer vs real number averaging, position of the pedestal window - all this explained in the above link. The main discussion was about the fact that Beni sees some slope (increase), when averaging over all the events, in the region before the real detector signal comes in case the signals are late. Mike suggested this may come from cross-talk from the other channels, but Beni has looked at this. Late signals can happen in cosmic showers (Eugene). Beni will do more studies when the computers are back.
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== FDC update ==
 
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- Lubomir showed some plots demonstrating his studies of the effect of the centroid reconstruction. First plot shows the rhombus defined by two crossing strips and the wire position w.r.t. middle of the rhombus. If the wire is in the middle, the corrections for the reconstructed wire position cancel out at each point. If the wire is half-way distance from the middle the corrections are maximal, still on average along the wire, they should cancel if everything is symmetrical. Second plot shows the variations of the residuals, on top of them the red curve is the distance of the wire to the middle of the rhombus - we have minimum when the wire is in the middle and maximum when it's half-way from the middle. Obviously there's correlation. 
 
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- The next plots show how different the variations of some quantities can be depending on whether the wire is in the middle or half-way from the middle. It turned out the wire picked up for the measurements in the Hall with 5Fe source was half-way from the middle, and the wire for the measurements with the spare package in EEL126 was in almost in the middle. One sees strong variations of the reconstructed wire position or up/down charge ratio for the measurements in the Hall, while there are no such variations with the spare package.
 
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- We looked once more at the corrections (discussed at the last meeting) using different methods. Eugene is concerned for some of the methods the corrections change sign depending on the shape of the signal. He suggested adding also the simplest calculation - just using the middle of the strip.
 
  
 
== Electronics ==
 
== Electronics ==

Revision as of 18:18, 2 July 2015

July 2, 2015 Drift Chamber meeting

Connection

  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.

Agenda

  1. CDC analysis update (Mike, Simon)File:MillepedeResults 2July2015.pdf
  2. FDC analysis update (Lubomir)
  3. Electronics (Fernando, Chris, Nick)
  4. Engineering
  5. Other


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