[Lowq] Minutes of the eg6 meeting on March 9

[Hovanes Egiyan]

Present: Raphael, Bayram, Stepan, Xiaohui, Hovanes, Yohann, Cole

On the phone: Sebastian

Notes by Hovanes


    Contents

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    * 1 DC calibrations
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_March_9_meeting#DC_calibrations>
    * 2 RTPC calibrations
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_March_9_meeting#RTPC_calibrations>
    * 3 EC calibrations
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_March_9_meeting#EC_calibrations>
    * 4 CC calibrations
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_March_9_meeting#CC_calibrations>
    * 5 Plans for a Pass0 cooking
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_March_9_meeting#Plans_for_a_Pass0_cooking>

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    DC calibrations

    * Bayram talked to Mac regarding the issue of x-vs-t and residual
      fits. According to Mac we do nto need to do another x-vs-t fit.
      The residual fit is the final fit if the figures from that fit
      look good.
    * Mac told Bayram that the dc3 plots looked already nice, and his
      conclusion was that we were very close to finalizing DC calibrations.

    * Stepan looked at some EC calibration files and noticed that
      invariant mass of e^+ e^- pairs is angle dependent. This may be
      due to the inadequate extrapolation of the trajectory into the
      solenoid's field and an inaccurate determination of the vertex
      location. This will have to be studied and special correction need
      to be developed or borrowed from Bonus run group.


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    RTPC calibrations

    * Stepan reported that there was a meeting last Thursday to discuss
      the RTPC calibrations. The issue with the double peaking in
      *s-dist* distributions was most likely resolved, and some of the
      aspects of RTPC calibration were discussed in more details.

    * Raphael pointed out that the He4 elastic events do not cover all
      pads before of the phi-segmentation of CLAS itself. Stepan thought
      that this should not be a problem since thre should not be much
      phi-dependence for the electron drift parameters. Therefore it is
      likely that we can use the same parameters for the pads which were
      not covered by elastic events.

    * Stepan requested that we cook RTPC calibration data at 1 GeV
      keeping only high level BOS banks (SEB banks) and RTPC related
      banks, and also filter events containing elastic events. This
      should simplify the RTPC calibrations.


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    EC calibrations

    * Cole Smith performed EC gain calibrations based on cosmic runs and
      verified with electrons. He up dated database with the new constants.
    * Cole also noticed that quality of the calibrations are not uniform
      over the face of the EC. He suspects that the attenuation lengths
      of the scintillators decreased with time. He sees a larger
      difference between the attenuation lengths determined from the
      CLAS data and measurements on the stand than it was ~10 years ago.
    * Cole will try to change the attenuation lengths and recalibrate
      the gains and see if it improves the E/P plots. He will also try
      to use pi0s to crosscheck the gain calibrations.


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    CC calibrations

    * Hovanes compared the constants from the 3 CC calibrations
      performed by Maurizio.
    * The SPE constants from a dedicated CC calibration runs were
      systematically higher (by ~!0%) than than those from the two
      production runs.
    * The constants from the two production runs were consistent between
      each other.
    * Conclusions were that we do not need to do more CC calibrations
      unles we see a problem.
    * The two constant sets from the production runs are linked to the
      eg6 runindex in caldb.


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    Plans for a Pass0 cooking

    * We discussed a schedule for a Pass0 with the first set of
      calibration constants. The pass will contain 5%-10% percent of the
      data. The agreement was to aim at April 2nd.
    * The system which will need to be ready by that time are:

       1. DC
       2. EC
       3. TOF
       4. CC
       5. IC

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