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    User name jianglai

    Log entry time 06:01:16 on December 11,2002

    Entry number 53875

    This entry is a followup to: 53741

    Followups:

    keyword=deadtime and false asymmetry

    I took a quick look at SDMCH rates in run 14949 --- 15uA deadtime run with IA =
    9V. The charge asymmetry of this run was1913(2.2)ppm. Below is a table
    of CFD single rates, MT single rates and 4-fold coincident rates of French
    detectors (averaged over 4 octants). The number in the parenthesis is the
    estimated fractional deadtime loss estimated based on:

    CFD single --> 35 ns
    MT single --> 32 ns
    4-fold coincidence ---> 50 ns (NPN) ---- this is the only term we correct in
    g0analysis for the moment

    ring# pure single(4 tubes) MT single(F+B) 4-fold coincidence

    1 2774.51(9.71%) 469.36(1.50%) 385.85(1.93%)
    2 1219.27(4.27%) 530.61(1.70%) 525.80(2.63%)
    3 844.08(2.95%) 533.20(1.71%) 617.55(3.09%)
    4 407.58(1.43%) 428.91(1.37%) 614.58(3.07%)
    5 422.81(1.48%) 496.90(1.59%) 580.96(2.90%)
    6 413.95(1.45%) 541.70(1.73%) 677.82(3.39%)
    7 436.36(1.53%) 528.59(1.69%) 820.11(4.10%)
    8 398.77(1.40%) 526.80(1.69%) 749.59(3.75%)
    9 434.15(1.52%) 667.88(2.14%) 812.34(4.06%)
    10 591.19(2.07%) 811.07(2.60%) 780.78(3.90%)
    11 757.35(2.65%) 1059.18(3.39%) 764.16(3.82%)
    12 968.83(3.39%) 1251.31(4.00%) 587.19(2.94%)
    13 1437.59(5.03%) 1461.65(4.68%) 464.14(2.32%)
    14 2288.20(8.01%) 2082.13(6.66%) 437.27(2.19%)
    15 3310.39(11.59%) 2774.14(8.88%) 431.88(2.16%)
    16 N/A ---- turned off during 15uA studies due to high single rates

    Attached plot just takes the sum of the loss due to CFD and MT singles and plot
    them against the detector number. They look agree quite well with the false
    asymmetry behavior we saw at 15uA (with IA = 9V).

    I dug out a small "homework" about the deadtime and false asymmetry,
    deadtime & false asymmetry
    This may explain how we propagate the deadtime loss to the slope of
    Wells plots. Also one may discover that the physics asymmetry acts the
    same way as charge asymmetry, as far as the false asymmetry of the deadtime
    is concerned. So if we have a 20ppm physics asymmetry and 1ppm charge
    asymmetry over 40 days, the false asymmetry of the deadtime is not at all a
    small amount.




    FIGURE 1