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    User name X. Zheng

    Log entry time 19:41:38 on November 9,2009

    Entry number 298612

    keyword=PVDIS DAQ Right arm pion veto not working

    The VETO signal for pion has been missing from fbTDC until today. After the access during with the pion VETO was plugged into fbTDC channel #69, this is the first time we can study its effect.

    Below shows the Cherenkov adcsum_c histogram for various cuts.

    top left: no cut

    top center: with electron VETO cut (GC.and.T1). This looks normal;

    top right: with pion VETO cut ((.not.GC).and.T1). Apparently the .not.GC part is not working here, since there is almost no difference between the top left (no cut) and this one;

    Middle left: normal;

    Middle center, middle right, and bottom left: Cerenkov for electron triggers of group 5. These look good;

    Bottom center and bottom right: Cerenkov for pion triggers for group 5. Because the .not.GC part is not working, these clearly contains both pion events and ALL electron triggers.

    No wonder from pion triggers we see a clearly non-zero asymmetry, same sign as electrons but only smaller size!

    FIGURE 1