Difference between revisions of "Meeting-4-5-2018"

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# CDC update
 
# CDC update
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## [https://logbooks.jlab.org/files/2018/04/3554679/CDC_2018_04_04.pdf Sergey's report]
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<!-- #* [https://logbooks.jlab.org/files/2018/04/3554679/CDC_2018_04_04.pdf Sergey's report] --->
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#* [http://www.jlab.org/Hall-D/detector/fdc/spring2018run/CDC_2018_04_05.pdf latest version of Sergey's report]
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#* [https://halldweb.jlab.org/cgi-bin/data_monitoring/monitoring/plotBrowser.py CDC pedestals]
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#* [http://www.jlab.org/Hall-D/detector/fdc/spring2018run/CDC_currents_BCGNtest.png CDC currents during the test]
 
# FDC update
 
# FDC update
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#* [https://logbooks.jlab.org/entry/3551757 FDC noise], [https://logbooks.jlab.org/entry/3553638 scope picture]
 
# fADC125
 
# fADC125
 
# Other
 
# Other
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−
 
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<!--
 
  
 
= Minutes =
 
= Minutes =
  
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Participants: Naomi (CMU) Sean(FSU), Eugene, Beni, Simon, Alex A., Thomas, Sergey, and Lubomir (JLab).
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Participants: Sean(FSU), Eugene, Beni, Simon, Alex A., Alex B., Sergey, and Lubomir (JLab).
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+
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= CDC settings for the rest of the run =
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- Beni summarized the information related to the CDC thresholds from the hardware threshold scans and his software threshold scan (p.1.1 above). After long discussion, the conclusion was that the hardware threshold gives a little better yields for the rho production. At the same time there's indication for a plateau at ~140 still to be confirm with the hardware scan above 140. However, the main massage is that the effect is not so big compared to the effect of the timing (p.1.2). Filtering the noise (p.1.3.) also gives some improvements, but the main gain in the yields come from the timing.
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- Alex A. showed that the effect of the hardware threshold on the hit efficiency is relatively small and acts mainly on the large drift distances (plot attached).
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- Sergey (see presentation above) analyzed the raw signals and sorted them in several categories: normal, saturated, "photons", cross-talk. He studied their percentage for many raw-mode runs (unfortunately at different condition); for "standard" 2018 running the background events are about 35%. He estimated the shadowing effect to be about 3-5%. Sergey proposed different filtering methods (like Time-Over-Threshold) eventually to be implemented in the firmware. Simom is using Sergey's noise filtering on the raw data to see the effect on the rho production.
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= CDC  =
  
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- Eugene asked about the amplitude distributions for hits at and out of the tracks. Naomi showed these distributions for different straws. She concluded that some of the straws (only several cards) are noisy and for these higher threshold (~140) would cut the noise, but that is not the case for the majority of the signals.  
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- Sergey showed an updated version of his report about the CDC background studies. It includes plots of the hit occupancy as function of the beam current with physics trigger and pulser (random) for inner and outer rings. While the two curves (physics and random) are parallel for the outer rings, at high occupancy as it is in the inner ring, this is not the case. There's no quantitative description yet. The plan is to take more data at higher intensities.
  
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- The conclusion is that based on the information that we have, the hardware thresholds are not so critical (in contrast to the timing cut/window that is already implemented). We still want to have a minimal threshold of 110 plus some special thresholds for the noisy channels. Naomi/Beni will generate these thresholds for the rest of the run. This conclusion may not be valid for reactions other than rho production, or for different pattern recognition in the CDC.
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- The phi-asymmetry in the inner CDC rings that Sergey found in case of no radiator and that is significantly suppressed when inserting W-foil (40 um) or emptying the target, can be explained by a synchrotron radiation from the vertically-bending magnet in the ramp to the tagger (Richard proposed this).  
  
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= Other =
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- Naomi suggested looking in the phi-asymmetry of the pedestals, that may be coming from the same polarized synchrotron radiation.
  
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- Sean studied in MC the BCAL vs Start Counter timings for proton tracks in the CDC. BCAL shows some deviations from the generated time at small p_T.
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= FDC =
  
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-->
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- Similar noise that has been observed last spring appeared again on two FDC wire cards (connected to one TDC module). The noise is present only after starting the DAQ and disappears soon after you stop it. Beni suggested disconnecting both cables from the TDC when looking with a scope on one of them. This was done later, but no difference in the noise was found.

Latest revision as of 18:11, 9 April 2018

April 5, 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 update
  2. FDC update
  3. fADC125
  4. Other

Minutes

Participants: Sean(FSU), Eugene, Beni, Simon, Alex A., Alex B., Sergey, and Lubomir (JLab).

CDC

- Sergey showed an updated version of his report about the CDC background studies. It includes plots of the hit occupancy as function of the beam current with physics trigger and pulser (random) for inner and outer rings. While the two curves (physics and random) are parallel for the outer rings, at high occupancy as it is in the inner ring, this is not the case. There's no quantitative description yet. The plan is to take more data at higher intensities.

- The phi-asymmetry in the inner CDC rings that Sergey found in case of no radiator and that is significantly suppressed when inserting W-foil (40 um) or emptying the target, can be explained by a synchrotron radiation from the vertically-bending magnet in the ramp to the tagger (Richard proposed this).

- Naomi suggested looking in the phi-asymmetry of the pedestals, that may be coming from the same polarized synchrotron radiation.

FDC

- Similar noise that has been observed last spring appeared again on two FDC wire cards (connected to one TDC module). The noise is present only after starting the DAQ and disappears soon after you stop it. Beni suggested disconnecting both cables from the TDC when looking with a scope on one of them. This was done later, but no difference in the noise was found.

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