[Lowq] inutes of the eg6 meeting on February 9

[Hovanes Egiyan]

  Minutes of the February 9 meeting


       From Lowqwiki

Present: Rafayel, Bayram, Stepan, F.-X., Hovanes, Yohann

On the phone: Raphael

Notes by Hovanes


    Contents

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    * 1 RTPC reconstruction after noise reduction
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_February_9_meeting#RTPC_reconstruction_after_noise_reduction>
    * 2 Study of the RTPC cathode radius
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_February_9_meeting#Study_of_the_RTPC_cathode_radius>
    * 3 Cherenkov SPE calibrations
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_February_9_meeting#Cherenkov_SPE_calibrations>
    * 4 DC Calibrations
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_February_9_meeting#DC_Calibrations>

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    RTPC reconstruction after noise reduction

    * After implementing the noise reduction discussed by Raphael during
      the precious meeting new files were cooked.
    * Raphael's studies
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/DQ_1>
      showed that there was noticeable improvement in the number of events.
    * For proton data there is a peak at ??=0 which may correspond to
      electrons.
    * For helium data the peak at ??=0 is very small.
    * Stepan suggested to study where in z this peak comes from. If it
      was from scattering on the target windows then it could be some
      recoil fragment from nuclear break-up.


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    Study of the RTPC cathode radius

    * Yohann studied the efects of changing the radius of the RTPC
      cathode on the drift path
      <http://www.jlab.org/%7Eperrin/bow_cath/> using MAGBOLTZ.
    * He concluded that a 5mm change would translate into a 20%
      modification of the phi angle.
    * We do not have a very good feeling how much the cathode could be
      deformed. May need to ask the engineers to figure out the
      deformation dues to the electrostatic force and due to pressure
      difference.
    * Yohann also looked at the *sdist* versus distance along the z-axis
      to see if he can see an effect there since the part in the middle
      would be displaced by the largest amount. The results so far were
      not very conclusive.
    * Stepan suggested to make 1D plots of slices in z with fine binning
      to see the *sdist*-distribution at each z-position.

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    Cherenkov SPE calibrations

    * Mairizio developed a procedure to calibrate the single
      photoelectron peak position using the data.
    * The procedure works because of presence of triggers unrelated to
      the CC pretrigger.
    * Maurizio put the new numbers into the database and link to the
      main runindex.
    * The uncertainties were by a factor of five larger that from the
      calibrations using dedicated CC calibration runs.
    * Hovanes will compare the new numbers with the numbers from the
      October's calibrations to decide hoe to proceed with the CC
      calibrations.
    * The plots from the calibrations can be seen at Maurizio's CC
      calibration page
      <http://www.jlab.org/%7Eungaro/maureepage/proj/Cerenkov/cc_periods/eg6.html>.



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    DC Calibrations

    * Bayram showed plots from the first DC calibration round.
    * Fits went successfully, except there seems to be a problem in one
      of the supoerlayers of sector 5 where Tmax seems to be different
      from the other sectors. Bayram will discuss this with Pawel or Mac.
    * Bayram did not have privilege to write into his own calibration
      database. Hovanes needs to get Bayram a write access to calib_user
      database.
    * We need to cook some data after Bayram's constants are in the
      database.

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