Difference between revisions of "Minutes-8-20-2015"

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# Engineering
 
# Engineering
 
# Other
 
# Other
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= Minutes =
 
= Minutes =
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== CDC update ==
 
== CDC update ==
  
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- Simon studied the wire offset as function of z (along wire) using beam data. In the logbook entry linked above, the two plots show the offsets for a straw at 9 o'clock when the track is above/below the wire. The offset variations are consistent with up/down deformation, possibly sagging of the tube or wire. To confirm this, need to look also at straws at 12/6 o'clock. Curtis, Naomi: if supported at the ends only, the tubes will sag by few mm, but after gluing them together there was no sagging.  
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- Nick made ground interconnections between all the boards in one sector. There was no change in the noise (Beni). Nick will remove the cables next week which will complete this test.
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- Simon and Mike continue to study the tube deformations along z.
  
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- Cosmic data will be taken over the weekend with mode 7.
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- Cosmic data will be taken over the weekend.
  
 
== Electronics ==
 
== Electronics ==
  
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- Nick showed pictures (logbook entry linked above) demonstrating the separation of the CDC broken wire.
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- Eugene reminded about the deadlines for the end of the FY15. The PR for the 100 spare pre-amps is out.  
  
 
== FDC update ==
 
== FDC update ==
  
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- Luke reported about the studies with 55Fe source with the spare package (plots attached). One can reconstruct the avalanche position in 2D: using up/down cathode charge ratio for position in direction perpendicular to the chamber and for the left/right position w.r.t. wire using the crossing of the centroid positions on the two cathodes. After fine calibration of the cathode channels one can see a hole where the wire is. Luke fitted the maximums at the two sides of the wire, first, in up/down direction and then left/right from the wire. The up/down maximum positions vary with the charge as demonstrated for two gas mixtures, 60/40 and 40/60 Ar/CO2. The left/right maximums are almost constants. The only explanation so far is related to the contributions from the ion tails that somehow vary with the charge.
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- Alignment offsets for the spring run different by up to 300 microns from the ones in the fall. Most likely this is due to the bias in the fall trigger.  
  
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- Using 55Fe source on the 4.5mm-thick cell results in very broad (in time) argon peak. The max drift time for the 40/60 gas is huge, ~20 microseconds which,  at least partially, may explain this effect to be related to the longitudinal diffusion.

Revision as of 17:40, 24 August 2015

August 20, 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. Detector performance document GlueX-doc-2775,

FDC

  1. CDC update (Mike, Simon, Beni)
  2. FDC update (Luke,Lubomir)
  3. Electronics (Fernando, Chris, Nick)
  4. Engineering
  5. Other

Minutes

Participants: Curtis, Mike (CMU), Fernando, Eugene, Luke, Beni, Dave, Nick, Simon, and Lubomir (JLab).

Detector performance document

- Lubomir updated the document on the portal with one-and-a-half page about the FDC. Some discussions about the resolution plots there: cathode resolutions in x and y-direction very different. Tracking only doesn't explain this contradiction, since in x direction the wire resolution that also uses tracking reaches 150 microns, to be compared with the cathode y-resolution of about 200 microns.

CDC update

- Nick made ground interconnections between all the boards in one sector. There was no change in the noise (Beni). Nick will remove the cables next week which will complete this test.

- Simon and Mike continue to study the tube deformations along z.

- Cosmic data will be taken over the weekend.

Electronics

- Eugene reminded about the deadlines for the end of the FY15. The PR for the 100 spare pre-amps is out.

FDC update

- Alignment offsets for the spring run different by up to 300 microns from the ones in the fall. Most likely this is due to the bias in the fall trigger.

- Using 55Fe source on the 4.5mm-thick cell results in very broad (in time) argon peak. The max drift time for the 40/60 gas is huge, ~20 microseconds which, at least partially, may explain this effect to be related to the longitudinal diffusion.

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