[Lowq] Minutes of the eg6 meeting on August 10

[Hovanes Egiyan]

  Minutes of the August 10 meeting


       From Lowqwiki

Present: Stepan, Will, Bayram, Hovanes

On the phone: Yohann, Lamiaa

Notes by Hovanes.


    Contents

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    * 1 TOF update
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_10_meeting#TOF_update>
    * 2 EC-timing
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_10_meeting#EC-timing>
    * 3 DC calibrations
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_10_meeting#DC_calibrations>
    * 4 Solenoid current
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_10_meeting#Solenoid_current>

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    TOF update

    * Lamiaa did multiple iterations on run 61107 for paddle-to-paddle
      calibrations.
    * She is going to apply these constants to all 5.7 GeV runs.
    * Hovanes pointed out that one needs to be careful when calibrating
      TOF p2p run-by-run so that in the calibration process you are
      subtracting/adding the same constants which were used during cooking.
    * Lamiaa will cook ~15 files from 61107 for Bayram to perform
      EC-timing calibrations.
    * Everyone wished a Lamiaa good recovery.

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    EC-timing

    * Bayram completed EC-timing calibration for 61107 and one of the
      runs from e1dvcs2.
    * Bayram showed a comparison of the eg6 EC-timing to e1dvcs2
      EC-timing
      <http://clasweb.jlab.org/rungroups/lowq/wiki/images/b/b8/EC_TIMING_EG6_DVCS.pdf>
      which he did.
    * The results are compatible, with e1dvcs2 having slightly larger
      width.
    * The INNER timing predicted by the code is on the order ~200 ps,
      the OUTER is ~250 ps. Stepan commented that it is a little worse
      after actual cooking is done.
    * The beta peak for neutral is 2% for INNER, ~3% for outer.
    * The shift in OUTER timing for neutrals is still not understood.
      Stepan is looking into this.
    * Stepan may change the code such that the EC timing comes from
      INNER when there is a "good" INNER timing information. This should
      improve the TOTAL timing resolution from EC.

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    DC calibrations

    * Seema is working oin DC calibrations from India.
    * She expects that she will be in US sometime in the end of August.
    * Seema e-mailed the first results from DC calibration for the first
      iterations. They looked reasonable.
    * The residual widths for 61107 seem to be larger that for the other
      runs.


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    Solenoid current

    * Stepan found out that the solenoid current is read into the
      cooking code from CalDB (as polarized target magnet) for a narrow
      run range. For other runs it is using either the default or the
      value from the TCL file.
    * This is done by hardcoding run numbers in the code. Removing this
      if may affect runs which do not have valid solenoid current
      values. Therefore we will simply add our run range to the range
      hardcoded in the source which will not make it any worse. Hovanes
      will look into this.
    * Eric, who actually could not attend the meeting, sent an e-mail
      where he mentioned that there might be issues with maximum
      solenoid magnet current. Apparently while we use solenoid current
      534 A during CLAS runs, the table is correct if calculated for
      current of 536.22 A. Therefore we might need to specify that this
      table is calculated for max. current of 536.22 A when running the
      code. Here is the quote from Eric's e-mail:

According to the GEM package, the reference current is 534 A while in order to reconcile our 
map with Jacques'one we would need a current of  536.22 A. This is the first difference (4 per 1000)

    * This needs to be investigated, either the code or the magnetic
      field file needs to be modified to correctly normalize the
      B-field. Also this may be a negligible effect.

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