February 25, 2015 Calibration

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GlueX Calibration Meeting
Wednesday, February 25, 2015
11:00 am, EDT
JLab: CEBAF Center, F326

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  1. Announcements
  2. Calibration Status
  3. Subdetector Plans


  1. Announcements
    1. The new web and database servers are now online. There are still some bugs being worked out. These include:
      1. CCDB is not accessible from offsite.
      2. Offline monitoring is not available on the new webserver - the work disk still needs to be mounted
      3. Various soft links in the group/work disks need to be updated (e.g. the link to the SQLite CCDB file)
    2. The next offline monitoring run is coming this Friday.
  2. Subdetector Plans
    1. We plan to run the offline monitoring again two weeks from now to evaluate the performance of the reconstruction before the upcoming run. The primary goals are to improve the calorimeter energy resolutions, and to improve the timing to the point where it can be used for some level of particle identification. We will review the progress made in the following items at the next calibration meeting.
      1. FCAL: Updated gains from the LED system for the Fall run should be added to the CCDB. Adesh is working on the calibration using electrons, and it would be very good to have some preliminary results from this as well. These calibrations will lead to updated high voltage settings for the spring run. The monitoring results from the Fall run with the updated constants will provide a useful benchmark for the performance for the spring run.
      2. BCAL: Will M. will update the CCDB with his latest pi0 gain calibration. His pi0 mass resolution has decreased to 15 MeV, and more improvement is possible.
      3. CDC: The plan is to run in the Spring with the nominal gas mixture for the CDC and FDC. The CO2 levels will be monitored with a special sensor, but it would be useful to have a plugin that could extract an independent estimate of the CO2/Ar gas mixture. Apparently it's easy for experts to tell this by eye, and the most useful metric is the maximum drift time. Naomi will look into automating this.
      4. FDC: It would be useful to get the gain calibrations in the CCDB, but they are not expected to have much effect, so this is not urgent. It would be more useful to have Lubomir's alignment constants in the CCDB, but they are not understood well enough yet.
      5. TOF: Some preliminary timewalk and time offset corrections need to be added in before the next run. Sean will attend the next TOF meeting this coming Tuesday to discuss how this can be accomplished.
      6. Start Counter: Progress is being made on further developing timewalk and propogation length corrections. The latter has been done with a simplified geometry, and adding results with a realistic geometry can be done by the next meeting. Hopefully some improved timewalk corrections will be ready as well.
      7. Tagger: Nathan said that the current tagger timing is as good as it can be without the external RF timing signal.
      8. Offline monitoring: We will need to include the necessary histograms to monitor these quanities, and others that show the performance of the detector. Now that the wiki is back, Sean will review these and discuss with the offline monitoring group.