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    User name E. Chudakov

    Log entry time 11:51:47 on July24,2003

    Entry number 106475

    This entry is a followup to: 104516

    keyword=Helicity check on Jul,18

    A cross-check of the helicity conventions for HRS, Parity and Moller
    subsystems was done on Jul,18, by increasing the helicity-driven beam
    current asymmetry to about 3% level. The results are as follows:

    HRS.. run 02418 asym(BCM u10)=-3.35% (End of Run log)
    Moller run 10926 asym(BCM u10)=+3.37+/-0.01%

    The signs have been opposite since long time. This is a matter
    of convention.
    The first analysis of the Moller run gave an asymmetry of about
    5%. It turned out that a non-linearity correction was done by default to
    the beam current in the Moller analysis. This correction was tuned
    to low currents (0.3µA), while the measurement was done at 4µA,
    where the correction became too strong. Without the correction,
    not needed for these currents anyway, the asymmetry is 3.37%.