Jun 15, 2017 Calorimeter

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Video Conferencing Information

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. Get power supply specs from Paul Smith and provide to Chris/Nick Paul has sent information to Chris and Nick

References

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

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Activities during the down
    • VME electronic crates have been shutdown. Auxiliary systems and trigger crates are still on.
  4. FCAL update (e-mail from Matt)
    • Unfortunately, I won't be able to make the meeting tomorrow.
    • Analysis of LED data continues in order to study time stability.
    • We also now have a nice EVIO skim exclusive omega events. This will be used to look at extra showers in the calorimeter, either from noise or hadronic splitoffs. It can also be used to study techniques to improve timing resolution by looking at the time difference of the two showers that make the pi0.
    • Jon continues his work with efficiency studies.
  5. BCAL update
  6. Calibrations
    1. GlueX-doc-2618 Update on Low Level Calibration Constants (Elton)
  7. Reconstruction and Simulation
    1. Charged Particle Clusterizer (Will)
  8. NIM articles
  9. Any other business

Minutes

Attendees: Elton, Mark, Adesh (JLab); Zisis, Andrei, Tegan, Ahmed (UofR); Christina, George (Athens); Sean (NW); Will (CMU)

  1. Announcements
  2. Action Items
  3. Activities during the down
    • VME electronic crates have been shutdown. Auxiliary systems and trigger crates are still on.
    • Tegan and Zisis recorded a collection of LED data to study pedestal widths vs SiPM bias voltage, and also runs with single bias lines on to enable single SiPMs.
    • Ahmed is preparing to analyze the data. He has obtained code that Mark used for similar studies in 2014 and got them to work, but has not yet started looking at data systematically. Can show data at the next meeting.
  4. FCAL update
    1. e-mail from Matt
      • Unfortunately, I won't be able to make the meeting tomorrow.
      • Analysis of LED data continues in order to study time stability.
      • We also now have a nice EVIO skim exclusive omega events. This will be used to look at extra showers in the calorimeter, either from noise or hadronic splitoffs. It can also be used to study techniques to improve timing resolution by looking at the time difference of the two showers that make the pi0.
      • Jon continues his work with efficiency studies.
    2. Timing calibration (Ahmed)
      • Timing for low intensity running seems to be ok and is being used for the upcoming production launch
      • The timing distributions for the high intensity running seem to be ok for neutral showers, but show anomalies in other topologies.
      • The suspicion was that the 4ns time offsets were to blame, but when these corrections were backed out, the anomalies remain.
      • It is unclear what the source of the problem is. Sean confirms that the time distributions have widened considerably.
      • Adesh and Sean are working to find the problem and fix it, but there should be sufficient time before we begin production on the high intensity runs.
    3. Geometry (Adesh)
      • The spacing between blocks was noted at a previous meeting to be incorrect in the geometry.
      • The new FCAL needs to be implemented and pull out some hard-coded values out of the code. Once the geometry is fixed, the gains and non-linearity corrections need to be revised.
      • Adesh will make changes once the timing has been settled.
  5. BCAL update
  6. Calibrations
    1. GlueX-doc-2618 Update on Low Level Calibration Constants (Elton)
      • Elton updated low-level calibrations document to reflect latest use and definitions of these constants
      • Table 1 gives the name of the constants, their number, the nomenclature, and table where they are stored.
      • The document has a link to a web page, where Mark has documented how the constants were obtained.
      • Sean: Request that all code associated with the calibrations be uploaded to the git repository.
    2. 4ns offsets in data (discussion)
      • Elton summarized pros/cons of the two methods available to determine the 4ns offsets:
        • production data, which was used for the current set of constants. This can use a few files from each run, but requires other calibrations to be completed (including tracking).
        • LED data. Elton used several runs from the spring 2017 to check constants that Mark obtained from production. It does not require a lot of LED triggers, but presently these are quite sparse in the production data, leading to a requirement of about 20 files to calibrate. In addition, the present algorithm only uses offsets that are obtained consistently for more than one configuration. When a single bias is used (two configurations for up/down LEDs), loss of one configuration results no constants being saved.
        • During the spring data, a series of runs were found with a single configuration. Ahmed: Finds that this was due to sector 3 pulser was not operating consistently, but is not understood why. Elton: These runs seem to cover all polarization states and have reasonable statistics.
        • Sean: Could increase the rate of LED triggers without impacting operation as long as the size of these events does not impact live time.
        • An alternative option would be to modify the scripting of the online to take a concentrated number of LED events at the beginning of the run. Elton: Note that at the moment the LED triggering is done asynchronously with taking data, so this implementation may require a dedicated effort. Dedicated runs with only LED triggers would not work because the latching of the clock cycle can change at the beginning of each production run.
        • Sean: FCAL also uses LED triggers to determine 4ns offsets, so a common philosophy with BCAL makes sense.
      • Zisis: Need to evaluate our understanding of the LED triggers and their stability. There seem to be "outages" which are not understood. We may also wish to revisit online monitoring of the LED triggers.
  7. Reconstruction and Simulation
    1. TDC calibration (Andrei)
      • Andrei presented plots that showed that there were multiple peaks in the timing distributions for runs 30859 and 31000 using fall 2016 calibrations
      • The multiple peaks were mostly eliminated using a calibration from this spring. Also, different versions of sim-recon were being used.
      • However, the elimination of the peaks seemed also to reduced the number of entries by about 30%. A more recent calibration, shows that the loss of data was reduced to 15%.
      • The latest sim-recon program now runs about 3 times slower than before.
      • Sean: The main change to sim-recon increases the efficiency for charged tracks and the processing time is slowed due to tracking more particles and also adding the electron hypothesis for every charged track. Likely changes to Andrei's work is likely due to changes to the calibrations. Evaluation of the distributions should be made with the latest code and constants.
    2. Charged Particle Clusterizer (Will)
      • Due to the shortness of time remaining, Will outlined his recent work and will present analysis of charged particle clusterizer at the next meeting.
      • Log entry contains an update, but some plots will be modified shortly
      • New proposal to how to handle charged tracks in the clusterizer
      • Feedback is welcome on what was posted in the log entry or new ideas on this topic.
    3. Exclusive pi0 use in gain calibration (Zisis)
      • Question to Tegan/Will: What is the latest on using exclusive pi0 to calibrate the BCAL gains?
      • Tegan: After 3 iterations, there is no more reduction in the pi0 width, which sits at about 14 MeV. (Will's approach has achieved about half this).
      • The code can be iterated much faster using a skim and Sean has pointed to examples so that a skim can be made first and save time during fitting for constants.
    4. Calibrations for MC
      • Sean: Thanks Mark for updating calibrations used in the MC to address some issues raised by Mike Staib. Mark: New constants have been loaded, but Mike has not checked them yet.
  8. NIM articles
    1. BCAL
      • Elton: would like to start a new iteration on the draft. What is the status?
      • Zisis: Only a few updates are not uploaded to git. Andrei has also provided updated figures
      • Will: Drafted a section on the gain calibration, but not yet uploaded.
      • George: Sent draft text to Zisis on the veff calibrations
      • Everyone: Agreed to upload the latest text/drafts/figures (even if preliminary) by tomorrow
  9. Any other business
    1. George: Revisited pi0 Dalitz decays. Has become pessimistic of the use of this reaction to study shower resolution. Acceptance of about 1% is found for both data and Geant4 MC. There was a suggestion to look into Geant3. He talked to Cristiano, who has looked into this reaction also with Geant3 and finds similar acceptance.