[Lowq] Minutes of the eg6 meeting on August 25

[Hovanes Egiyan]

  Minutes of the August 25 meeting


       From Lowqwiki

Present: Stephen, Andrea, Hovanes, Aji, Sergey

On the phone: Kawtar, Raphael, Ahmed, Raffaella

Notes by Hovanes.


    Contents

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    * 1 Main RTPC status
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_25_meeting#Main_RTPC_status>
    * 2 RTPC Tests
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_25_meeting#RTPC_Tests>
    * 3 Readout Electronics
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_25_meeting#Readout_Electronics>
    * 4 Gas handling system
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_25_meeting#Gas_handling_system>
    * 5 Organizational issues
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_25_meeting#Organizational_issues>
    * 6 Other issues
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Minutes_of_the_August_25_meeting#Other_issues>

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    Main RTPC status

    * Main RTPC is almost complete. Cathode is also in place. RTPC can
      now hold high voltage.

    * We need to check for the small hole for the gas flow in the
      cathode assembly.

    * The new RTPC will probably be closed today. But we are still
      waiting for the divider and thick sealant. These items are
      expected to be here today or tomorrow.

    * Cable tray and short tube are here. In principle we can start
      transferring cables RTPC this weak, but mostly likely it will
      happen sometime next week when we have DAQ components too.

    * Before mounting the new RTPC on the cart we need to make sure that
      the foil assembly is good because it is hard to remove the foil
      when it is already mounted on the cart.


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    RTPC Tests

    * Prototype is still being tested. Neon/DME, He/DME and ArgCO2 were
      tested, and the signals look pretty good. Neon/DME mixture
      produces really good signals on the scope.

    * It would be good to try to do track reconstruction for Neon/DME
      misture. The constants in the RTPC tracking code would need to be
      adjusted for the new gas.

    * Stephen will prepare a test plan for the next meeting.


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    Readout Electronics

    * Raffaella gave an update on the current status of the update of
      the readout electronics
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Status_of_Readout_Electronics_-_08-25-09>.


    * After communicating with the experts from CERN Genova
      collaborators came to a conclusion that we cannot combine
      multi-event readout and sparcified readout. Therefore, we will be
      using non-sparcified multi-event mode with zero suppression. In
      this case we do not have 200?s deadtime due to list compilation.
      Raffaella pointed out that zero-suppression is extremely important
      because without that the event rate will decrease by a huge factor.

    * Detail studies showed that with 13 cards in each create we can
      only achieve 800 Hz event rate on RTPC. Studies showed that if we
      have only 4 cards in each crate then the event rate can be up to
      2.4KHz (still depends on the event size). Therefore we would like
      to use six crates for which we would need to purchase more
      components.

    * Sergey does not think that we can have 6 computers for readout.
      Then he pointed out that we need to test a configuration with 2
      branches on a single RORC which we never tried before. Various
      option with the number of computers and RORC will need to be
      considered.

    * For more details on what we would need to obtain for the 6-crate
      configuration see Raffaella's wiki entry
      <http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/Status_of_Readout_Electronics_-_08-25-09>.



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    Gas handling system

    * The gas panel construction is complete. Some wiring still needs to
      be done.

    * Pictures of the still incomplete panel are available on Doug' web
      page.
      <http://www.jlab.org/%7Etilles/miniT/Bonus%202009/thumb_index.html>

    * A student from UNH will be here next week to help with the control
      system.

    * The gas panel will be moved to EEL building at the end of this
      week so that we can start leak tests next week.


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    Organizational issues

    * Kawtar reminded us that we need to work on the run plan for EG6.

    * We also need to work out the run coordinators schedule.

    * Hall B and accelerator administration need to be informed about
      specific requirements for our beam conditions:

       1. Beam current > 200 nA
       2. Beam energy of single pass in the beginning of the run.

    These conditions need to be in experiment's RSAD and/or ESAD. 

    * Stepan told the group that the Hall B beam stopper might not be
      enough to allow us go to beam currents above 200 nA because the
      Faraday cup is capable of handling ~30-40 nA at 6 GeV energy.
      Obviously, the presence of the beam stopper will also decrease the
      avarage electron energy in the beam, so that limit will be higher
      for us. But this needs simulations, and Natasha is currently
      working on it.

    * Kawtar will work on a draft version of the run plan and we will
      discuss it on the following meetings.


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    Other issues

    * Hovanes told the group that according the current plan the CVS
      repository for the CLAS offline software will be frozen in
      September 1st for the transition to the new offline software
      scheme. These involves not only transition from CVS to SVN but
      also restructuring of the current directory tree and replacement
      of the "make" scheme with "scons" scheme.

    * The group unanimously expressed their opposition to such a haste
      transition because this would require significant manpower in a
      time when we need to spent a lot of effort on the commissioning of
      the new RTPC.

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