January 14, 2015 Calibration

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GlueX Calibration Meeting
Wednesday, December 17, 2014
11:00 am, EDT
JLab: CEBAF Center, F326

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  1. Announcements
    1. Calibrations and REST data
    2. Calibrations and MC
    3. Software Review, February 10-11, 2015
    4. Collaboration Meeting February 19-21 at Jefferson Lab
  2. Calibration status/updates
    1. FCAL
    2. BCAL
    3. CDC
    4. FDC
    5. TOF
    6. Start Counter
    7. TAGH
    8. TAGM
    9. TDCs
    10. Software
  3. Simulations
  4. Data Monitoring
    1. Status Update (Kei)
    2. Commissioning Software
    3. Run Browser, Plot Browser, and Time Series webpages
  5. AOB


Attending: Sean, Amiran (NU); Curtis, Naomi (CMU); Kei, Simon, Paul, Nathan, Will M., Eugene, Mark I., Elton, Lubomir, Mark D., Adesh, Mike S. (Jlab); Matt S. (IU); Justin, Tegan, Noemi, Andrei (Regina); Volker (FSU)


  1. In the Offline Software meeting last week, it was decided to create data files in REST format because of the interest in analyzing reconstructed tracks and showers to search for bumps and other higher-level analyses. The first set is planned to be generated started on Jan. 23, and will fold in all improvements in reconstruction and calibration at that time.
  2. From personal experience, Sean reminded everyone that calibration tables used in reconstruction higher than hit-level will also be used when analyzing simulated data, and appropriate values should be filled into the tables under the "mc" variation.
  3. We will be subjected to a Software Review on February 10-11. Curtis, Mark I., and David L. have been meeting to prepare for this.
  4. We talked briefly about planning for next month's Collaboration Meeting. We expect that most of the calibration-related activity will be reported by the individual detector groups. If all goes well, Sean can give just a summary talk in the offline section and will coordinate with Mark I.


  • Status of gain calibrations is essentially unchanged from last year. The pi0 calibration code is tested, so the challenge is to select a clean sample of pi0's of sufficient size to use. The first sample of pi0's that Matt tried to use had an S/B of ~1/1, which did not provide good results. Using various quality cuts (e.g. timing and ratio between peak integral and peak height), he can get a very clean sample but that has very limited statistics. He's currently trying to find an acceptable middle ground.
  • Eugene asked about the overall scale factor calibration, and noted that there are a lot of electrons in the central part of the detector which could be used to calibration that portion at least.
  • The major challenge is that there is a lot of noise in the data which didn't show up in earlier testing (Sergey P. estimated that ~80% of clusters are due to noise), and this problem needs to be carefully studied so that it can be fixed.


  • Elton posted a note summarizing the low-level BCAL constants. Sean is helping to create the tables and integrate them into the reconstruction code.
  • Mark D. has added the attenutation lengths derived from the data to the CCDB. The lengths are longer than expected (by ~10-20%) due to reflections, which lower the derived energies. Adding these parameters did not improve the resolution, however.
  • Will M. has just run over all the data, and is looking at the total number of pi0's and using the pi0's for gain calibration.
  • There was a detailed discussion with Andrei about the particulars of the attenuation lengths, since some of the effects may depend on issues related to the light guides or some other details of the detector, which may change over time. These systematics should be studied in detail, but the the particulars will be discussed more in Friday's Calorimetry meeting.


    1. FDC
    2. TOF
    3. Start Counter
    4. TAGH
    5. TAGM
    6. TDCs


Several topics of general interest were covered in the previous discussion.

  • Having a list officially approved runs for analysis would be very useful. Justin is currently using a python script to determine a list of runs from the current run info DB. Justin agreed to post his script and the list of runs. It would be good to have a human make the final approval.

  1. Simulations
    • Improvements in understanding the detector response from data analysis will need to be folded
  2. Data Monitoring
    1. Status Update (Kei)
    2. Commissioning Software
    3. Run Browser, Plot Browser, and Time Series webpages
  3. AOB

  1. Post python script and list of good runs in a publically accessible location (Justin)

Action Items