February 11, 2015 Calibration

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

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  1. Announcements
    1. Software Review, February 10-11, 2015
    2. Collaboration Meeting February 19-21 at Jefferson Lab
  2. Timing Offset Calibrations (Mike S.) - slides
  3. Calibration status/updates
    1. FCAL
      1. FCAL Calibration Status
    2. BCAL
    3. CDC
      1. First CDC straw alignment offsets (Simon)
    4. FDC
    5. TOF
    6. Start Counter
    7. TAGH
      1. TAGH efficiency
    8. TAGM
    9. Calibration Dashboard
  4. Simulations
  5. Data Monitoring
    1. Status Update (Paul/Kei)
    2. Commissioning Software
    3. Run Browser, Plot Browser, and Time Series webpages
  6. AOB


Attending: Sean (NU); Simon, Paul, Mike S., Manuel, Nathan, Will M., Kei, Noemi, Eric, Mark D., Alex B., Eugene (JLab); Matt S., John Z. (IU); Justin (MIT); Naomi (CMU); Mahmoud (FIU); Regina (Tegan)

Timing Offset Calibrations

Mike gave a brief update on his automated timing offset procedure. We looked at his current results for time resolutions between the start counter and various detectors. The observed resolution is a combination of the start counter resolution and that of a particular detector. Right now, Mike is testing his procedure with different runs, and fixing the bugs that have been exposed. He's found some differences in how the fADC reports results and error conditions between mode 7 and mode 8, and has accounted for this. He's also worked with Simon to make time-based tracks available in runs with zero magnetic field, where they were not available before. The quality and detector matching of these tracks are not as good as when the magnetic field is on. He will also compare these results with those obtained from simulations.



Work is progressing in BCAL gain calibrations using pi0's. A similar algorithm as that used by the FCAL is being used, with the added complication that each BCAL cell is read out on 2 sides (upstream/downstream), instead of the 1-sided FCAL readout.


Simon used a few long cosmic runs taken in the fall to determine the first wire alignment constants and add them to the CCDB. The shifts in the location of the wire ends that he obtains are ~100 um, though they can be as large as ~500um.

Simon also uploaded a new time-to-drift distance table for 1200 A magnetic field, with a 56/44 Ar/CO2 mix. A similar table already existed for magnet-off data. The new table results in a position resolution of 150 um for long drift distances. (In both cases, near the wire the position resolution is ~250 um, consistent with results from the prototype).

Mike is working on the efficiency calculation.


Lubomir continues to work on the package-by-package alignment.

Simon needs to make some new tables to hold the FCAL gains, since the current tables don't take into account the half-sized strips. The hit factories will need to be updated as well.


Sean noted that it was communicated to him that progress is being made in timing calibration, and paddle alignment is currently being looked at.

After the meeting: It was noted that the tdc_shift calibration (which removes the 6-fold uncertainty) for later runs was not always set correctly. Kei and Sean are working on updating this constant and new values should be in later today

Start Counter

Constants from the test stand for attenuation length and propogation speed have been put in the CCDB. Current efforts are in determining these and other time calibrations. The reconstruction code will also need to be updated to use these.


      1. TAGH efficiency


No new news - resolving hardware issues has been the priority.


Paul has implemented a new constant for the RF frequency, since we'll be running at a lower frequency this spring (~250 MHz versus ~500 MHz).

Sean has implemented a scheme to automatically load the correct magnetic field for different runs using the CCDB. This scheme works with the fall data; procedures for setting the correct constants for new runs are still being discussed.

Sean reviewed the Calibration Dashboard and noted that he is collecting information on detector resolutions and efficiencies.


Sean and Simon are still running checks on MC they have generated. Calibrations should be checked and an issue with missing CDC hits should be resolved before more simulations are run.

Data Monitoring

It was agreed that the situation with offline monitoring is stable enough that status reports can be left to the offline meeting. Instead, once data taking resumes, it would be useful to review some of the output of the monitoring. To do so, as calibration procedures are developed, they can also provide useful output (histograms, etc.) to the monitoring as well.

Generally, detector groups should review what they are contributing to the offline monitoring to see if they want any changes made.