Difference between revisions of "Minutes-11-19-2015"

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November 19, 2015 Drift Chamber meeting
 
November 19, 2015 Drift Chamber meeting
  
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# CDC update (Mike, Simon)
 
# CDC update (Mike, Simon)
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#* [https://logbooks.jlab.org/entry/3360352 logbook entry 3360352]
 
# FDC update (Lubomir, Luke)
 
# FDC update (Lubomir, Luke)
−
#* New resolution results: [http://www.jlab.org/Hall-D/detector/fdc/commissioning/StripChargeDistributions.pdf]  
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#* New resolution results: [http://www.jlab.org/Hall-D/detector/fdc/commissioning/StripChargeDistributions.pdf], [http://www.jlab.org/Hall-D/detector/fdc/commissioning/CathRes_new.pdf cathode resolution],[http://www.jlab.org/Hall-D/detector/fdc/commissioning/WireRes_new.pdf wire resolution], [http://www.jlab.org/Hall-D/detector/fdc/commissioning/ChargeMuXres.pdf residuals] 
 
#* [http://www.jlab.org/Hall-D/detector/fdc/TR/TRD_plan_fall2015.pdf plan for TRD studies]
 
#* [http://www.jlab.org/Hall-D/detector/fdc/TR/TRD_plan_fall2015.pdf plan for TRD studies]
 
# Electronics (Fernando, Chris, Nick)
 
# Electronics (Fernando, Chris, Nick)
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#* svn ls https://halldsvn.jlab.org/repos/trunk/publications/GlueXFDC
 
#* svn ls https://halldsvn.jlab.org/repos/trunk/publications/GlueXFDC
 
# Other   
 
# Other   
−
 
−
<!--
 
  
 
= Minutes =
 
= Minutes =
  
−
Participants: Curtis, Naomi, Mike (CMU), Sean (NU), Fernando, Cody, Luke, Dave, Chris, Nick, Simon, Beni, and Lubomir (JLab).
+
Participants: Curtis, Naomi, Mike (CMU), Sean (NU), Cody, Luke, Dave, Chris, Nick, Simon, Beni, and Lubomir (JLab).
  
 
== CDC update ==
 
== CDC update ==
  
−
- Mike showed presentation (attached) about precise fitting of the time-to-distance in presence of tube deformation. The 3D plots show the average drift distance (from track fitting) as function of drift time and wire offset from the center. The Garfield results don't describe the data very well, but using the same functional form they were fitted to the data. The time-to-distance relation obtained in this way turned out to be different for different runs (not clear why). As a result of this procedure the resolution looks very good (last slide). 
+
- Nick found the broken wire and separated it from the HVB (see log entry above). He fixed one more channel by replacing the HVB card.  
−
Once Mike has the correct relation he plans to run the alignment procedure once more.
+
  
−
- Plan to run DAQ with both CDC and FDC over the weekend. Cody made some fixes in the firmware.  
+
- Mike is looking now at the beam data; will apply the same correction as with the cosmics to correct for the tube sagging.  
  
 
== FDC update ==
 
== FDC update ==
  
−
- On Wednesday the spare package has been moved to the Hall (picture). Signal and LV cables have been connected. We will use the right side of the ST crate - the setting of the TI needs to be changed. HV connections and grounding will be done soon. The middle of the package is above the beam line, thus making space around it. There will be also no need to remove it when backing the target and working on the CDC. Curtis mentioned the need to protect the package at the downstream side - after the meeting aluminum cover was installed there.  
+
- Lubomir showed latest results on the resolution studies. The resolutions improved gradually due to some residual corrections, better alignment, tracking and finally by using Mathieson/Simon's function when fitting strip clusters; first plot shows the different functions used. Cathode resolution (second plot): red - resolution along y from tracking; green - after subtracting the tracking contribution (assumed to be about 100 microns); blue - resolution estimated from reconstructing wire position. Need about 80 microns contribution to explain the difference (quadratically) between green and blue - may come from the extension of the avalanche along the wire. Wire resolution (third plot): red -reconstructed from tracking; green - after subtracting the tracking contribution of 100 microns. In summary: cathode resolution (along wires) ~120 microns; wire resolution ~110 microns (between 1 and 4.5 mm from the wire).
 +
 
 +
- We started preparing a document describing the tests with the spare package.
  
 
== Electronics ==
 
== Electronics ==
  
−
- Lubomir and Luke measured the response function of the FDC preamp-cable-fADC125 system using the DAQ in the tagger. We used a charge injector at the input - step function from pulse generator on 1pC capacitor on a board that Fernando used before. All the millivolts in the above plots correspond to the step amplitude. We first looked with a scope and found that the peak and tail-cancellation parts saturate in different way (first two plots) - Fernando says that's normal.
+
- Lubomir and Luke finished the response function measurements for both FDC and CDC preamps. First two plots show typical response functions (from fADC125). Third plot: Max/Min absolute values of the response function vs the input charge  for both FDC and CDC. The linear range for the CDC is wider than for the FDC (in fADC125 units). Fourth plot: Max/Min ratio is constant for the CDC but goes down with the charge for the FDC. It is not clear why (saturation effects?) but helps to eliminate the ion tails, which is not the case for the CDC.
 +
 
 +
- Lubomir also used a scope to measure the FDC preamp+cable response function (last plot). The gain is about 1.8mV/fC. When compared with the fADC amplitude it saturates in a different way, not clear why.
 +
 +
== CDC/FDC papers ==
 +
 
 +
- Beni created templates for the NIM papers.
  
−
- The last plot shows summary of the measurements with fADC125: the max (red) and min (blue, absolute value) of the response function for different input charges. The range with good linearity of the max is narrower that that range for the tail-cancellation part (the minimum). Thus, the poor dE/dx resolution of the FDC can be explained by saturation effects present already at ~2000 units, i.e. half of the fADC125 range. The undershooting is about 20-25% of the peak amplitude. Looking and the Naomi's result for the CDC pre-amp we see that there the tail-cancellation is only about 10%. This might be an explanation for the ion tails seen in the CDC. We will repeat the measurement with a CDC pre-amp.
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== Other ==
  
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-->
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- Next meeting in two weeks - on December 3.

Latest revision as of 19:28, 19 November 2015

November 19, 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 update (Mike, Simon)
  2. FDC update (Lubomir, Luke)
  3. Electronics (Fernando, Chris, Nick)
  4. Engineering (Dave)
  5. templates for CDC and FDC NIM papers
  6. Other

Minutes

Participants: Curtis, Naomi, Mike (CMU), Sean (NU), Cody, Luke, Dave, Chris, Nick, Simon, Beni, and Lubomir (JLab).

CDC update

- Nick found the broken wire and separated it from the HVB (see log entry above). He fixed one more channel by replacing the HVB card.

- Mike is looking now at the beam data; will apply the same correction as with the cosmics to correct for the tube sagging.

FDC update

- Lubomir showed latest results on the resolution studies. The resolutions improved gradually due to some residual corrections, better alignment, tracking and finally by using Mathieson/Simon's function when fitting strip clusters; first plot shows the different functions used. Cathode resolution (second plot): red - resolution along y from tracking; green - after subtracting the tracking contribution (assumed to be about 100 microns); blue - resolution estimated from reconstructing wire position. Need about 80 microns contribution to explain the difference (quadratically) between green and blue - may come from the extension of the avalanche along the wire. Wire resolution (third plot): red -reconstructed from tracking; green - after subtracting the tracking contribution of 100 microns. In summary: cathode resolution (along wires) ~120 microns; wire resolution ~110 microns (between 1 and 4.5 mm from the wire).

- We started preparing a document describing the tests with the spare package.

Electronics

- Lubomir and Luke finished the response function measurements for both FDC and CDC preamps. First two plots show typical response functions (from fADC125). Third plot: Max/Min absolute values of the response function vs the input charge for both FDC and CDC. The linear range for the CDC is wider than for the FDC (in fADC125 units). Fourth plot: Max/Min ratio is constant for the CDC but goes down with the charge for the FDC. It is not clear why (saturation effects?) but helps to eliminate the ion tails, which is not the case for the CDC.

- Lubomir also used a scope to measure the FDC preamp+cable response function (last plot). The gain is about 1.8mV/fC. When compared with the fADC amplitude it saturates in a different way, not clear why.

CDC/FDC papers

- Beni created templates for the NIM papers.

Other

- Next meeting in two weeks - on December 3.

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