Difference between revisions of "Sep 20, 2018 Calorimeter"

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(Minutes)
(Action Items)
 
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# BCAL and FCAL: Develop standard fiducial volume cuts for the calorimeters
 
# BCAL and FCAL: Develop standard fiducial volume cuts for the calorimeters
 
# FCAL: Cross check MC changes by Richard to make sure that gains are not affected in both Geant3 and Geant4 (Matt/IHEP)
 
# FCAL: Cross check MC changes by Richard to make sure that gains are not affected in both Geant3 and Geant4 (Matt/IHEP)
 +
# Fix FCAL online monitoring plugin to properly plot low level digi quantities in 2D displays.  2D display of pedestal is hard to get because occupancy plot is filled in a different loop. (Matt)
 
# <strike> BCAL: Interchange LED trigger cables and see if upstream and downstream features change (Elton and Mark) </strike> See Log Entries [https://logbooks.jlab.org/entry/3593920 3593920] and reference.  
 
# <strike> BCAL: Interchange LED trigger cables and see if upstream and downstream features change (Elton and Mark) </strike> See Log Entries [https://logbooks.jlab.org/entry/3593920 3593920] and reference.  
  

Latest revision as of 18:21, 20 September 2018

Meeting Time: 11:00 a.m.

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Participant Direct Lines

  • JLab Phone in CC L207 is 757-269-7084 (usual room)
  • JLab Phone: in CC F326 is 757-269-6460
  • Phone in the Regina Video-conference Suite is 306-585-4204
  • Athens Phone: in Christina's office is 011-30-210-727-6947

Action Items

  1. BCAL and FCAL: Develop standard fiducial volume cuts for the calorimeters
  2. FCAL: Cross check MC changes by Richard to make sure that gains are not affected in both Geant3 and Geant4 (Matt/IHEP)
  3. Fix FCAL online monitoring plugin to properly plot low level digi quantities in 2D displays. 2D display of pedestal is hard to get because occupancy plot is filled in a different loop. (Matt)
  4. BCAL: Interchange LED trigger cables and see if upstream and downstream features change (Elton and Mark) See Log Entries 3593920 and reference.

Complete after new launch

  1. From Mike's work: -cos(phi) type dependence in the data and a phi dependence at the downstream end of the bcal. See Sep 21, 2017 Calorimeter Meeting.

References

  1. FCAL HDFCAL log book
  2. BCAL HDBCAL log book

Tentative Agenda

  1. Announcements
  2. Action Items
  3. GlueX-Collaboration-Sep-2018
  4. Run Updates
    1. FCAL
    2. BCAL
  5. Calibrations
    1. FCAL Pedestals and LED Rate (Matt)
    2. FCAL Radiation Damage (Jared)
    3. pi0 gun for gain calibration (Colin)
  6. Reconstruction and Simulation
    1. Pi0 Calibration DocDB page Update with Layer 4 Cosmics corrections (Tegan)
  7. NIM articles
  8. Any other business

Minutes

Attending: Elton, Mark, Colin, George V., Christina (JLab); Will (CMU); Jon, Matt, Jared (IU); Tegan, Colleen, Zisis, Ahmed (UofR); Sean (FSU); Rupesh (FIU).

  1. Announcements
    • Accelerator is coming back online. Vacuum leak and obstruction seems to have been fixed. Expect beam as early as Friday.
  2. Action Items
    • FCAL MC changes: Sean expects non-linearities to possibly change. Has generated a new MC sample and it should be looked at. Sean will send the links/info to Matt.
    • BCAL LED runs: Ahmed has started looking at the runs and sees only downstream LED working. Will confirm and will give feedback to Elton and Mark.
    • Matt added an action item.
  3. GlueX-Collaboration-Sep-2018
  4. Run Updates
    1. FCAL
      • PMTs are on and ready. Replaced eight bases, all dead ones. Still some dropping HV at the outer edge, but will continue to monitor. Presently spares are limited to a couple.
    2. BCAL
      • Upstream chiller now seems to be operating at a reasonable level. See Log Entry 3594999 although pressures are still higher than downstream chiller.
      • Glitch in operation of BCAL and FCAL temperature feedback loops concerned Fernando and HCO was downgraded to 'not ready'. Mark has restarted the feedback script and that seems to have fixed the problem. [After lunch, Fernando requested that the feedback keep fans below 5000 rpm].
      • Ahmed has been cleaning up occupancy plots and preparing a presentation with annotations for discussion. Zisis is traveling to JLab for shifts and the collaboration meeting.
  5. Calibrations
    1. FCAL Pedestals and LED Rate (Matt)
      • FCAL monitoring of spring 2018 data showed the pi0 mass shift for some runs. The runs ( around ~42221) were found to correspond to an (accidentally) high pulsing of the LEDs, up to 1kHz where 10 Hz is nominal.
      • The causality of pi0 mass shift due to pedestals is not established.
      • Colin, Mark and Elton will take a look at pulses on the scope and see how the baseline shifts. Note added: No baseline shifts were found, but at high rates LED pulser rates it was noted that the HV on some pmts was sagging. See Log Entry 3595928.
    2. FCAL Radiation Damage (Jared Foote)
      • Normalized LED pulse heights were plotted as a function of time for different LED colors.
      • It is found that for blocks between 10-20 cm from the beam line, the normalized pulse decreases between the beginning and end of the spring run by several %. The effect is largest for violet light, as expected from radiation damage.
      • Since the LED light shines in the front of the glass, it is possible that all damage is at the upstream end and would have little effect on particles. Therefore, with out further assumptions, the measured degradation cannot be easily translated into particle response. Matt: On the other hand, regions where no effect is seen can be assumed to have little radiation damage.
      • Colin: Suggested to look at the same effect on a per block level. Jared/Matt: Statistics should be sufficient and they will look al the effect for the inner blocks.
      • Mark: Why is there so much dispersion in the data? Matt: Not understood. Note that absolute drifts are seen of the order of +/-3%, deviations both in common mode and stochastic and this may contribute.
      • Colin: Could this effect be due to dying bases? Mark: Could remove dead bases from the analysis to eliminate this possibility.
    3. pi0 gun for gain calibration (Colin)
      • Investigating pi0 mass calibration near beam hole.
      • Generated MC and checked change in pi0 data in the simulated sample. Changes in pi0 peak and distortion of spectrum are visible, but not dramatic.
      • The 2-photon mass distribution in data has a large low-energy tail (assumed to be background) and a broad distribution covering the pi0 mass range, but no clear peak. Calibrating this data without a peak is not possible, so this needs further study.
  6. Reconstruction and Simulation
    1. Pi0 Calibration DocDB page Update with Layer 4 Cosmics corrections (Tegan)
      • Colleen worked on determining gain calibrations for BCAL in layer 4 and has obtained new constants.
      • Constants have been uploaded and Tegan has iterated his pi0 gain calibration with the new layer 4 constants. This has changed the layer 3 constants by a few %.
      • The effect on the pi0 mass resolution has been minimal.
      • Colleen is preparing a report on her work.
  7. NIM articles
  8. Any other business