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    User name jpchen

    Log entry time 15:41:40 on April 9,1999

    Entry number 20

    keyword=3/31 analysis meeting minutes

    Minutes of 3/31 analysis meeting:

    Present: Alexandre Deur, Pibero Djawotho, Ioannis Kominis, Zhengwei Chai,
    Marat Rvachev, Mark Jones, Todd Averett, Joe Mitchell, Bogdan Wojtsekhowski,
    and Jian-ping Chen.

    Bogdan gave a presentation on the detectors and it's analysis.
    Some questions and discussion during and after Bogdan's presentation.
    There is a good web page for the shower counter information (following the
    hall A detector page). Also distributed information on the study of Cherenko
    PMTs. A note on the geometrical data base of the detectors in electron arm is
    available on web page http://www.jlab.org/~njenkins/public_html.

    Alexandre:
    I have used the new survey numbers to get the position of the
    beam. I will try to give all the raster codes to Xiaodong today so he will be
    able to put them in espace.
    All the rasters number rely on the Harp data:
    The beam center is given by the BPMs data which are
    corrected (it's a linear relation) to fit the harp data.
    The beam size is also given by the BPMs calibrated with
    the Harp. The calibration number is around 1.2 (so far, I am using old codes for
    the BPM size and I am checking if it's still the same numbers with espace BPM
    data). This 1.2 factor is consistent with the fact we have a low pass filter in
    BPMs acquisition which is shrinking the signal amplitude. (Luminita has the same
    factor for VCS and it should not change unless people change the filter or the
    raster calibration numbers in espace).
    The phase removal (phase between raster and BPMs) gives
    a (not too nice) strait line of width around +/- 0.5 mm and I don't think I can
    get something better with this kind of analysis. It's a first uncertainty on the
    beam position event by event.

    Ioannis: Mostly on target analysis.

    Pibero: continue working on scintillator/trigger efficiency. Using cut on Cherenkov, shower detectors and VDC.