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    User name R. Michaels

    Log entry time 11:31:08 on July23,2005

    Entry number 149157

    keyword=prelim. scan results (2 runs)

    Results from the Y scan. Detectors all look ok.

    Fig 1 shows the X,Y at target, the lower panels show my cuts for
    "top" and "bottom" of acceptance. What matters is the ratio of
    the number of entries in these "cut histograms". So, run 2232
    (fig 1) these #entries from analysis of 200K events (~20% of
    the run) and the T/B ratios were

    L-arm top(T) 2336,   L-arm bottom(B) 2795.   T/B = 0.836
    R-arm top(T) 2884,   R-arm bottom(B) 2817,   T/B = 1.023

    Run 2233 (Y = +1 mm) results :

    L-arm T 2630   L-arm B 2742   T/B = 0.959
    R-arm T 2980   R-arm B 2818   T/B = 1.057

    Note, increasing Y by 1 mm increased T/B by a few percent, but this
    could be a purely geometric effect (possibly ambiguous), however
    I think T/B would have decreased if there was a blockage.
    But this is still pretty crude and I need to do cuts on Y & Z
    target, bigger Y changes, etc. Later...

    Note, we can also get crude info on occlusion from looking at scaler
    rates. I used the Podd scaler analysis package to obtain rates.
    It is important to normalize to beam current since this drifted
    with time. I pick "u3" for the current. Doing that I get for
    Run 2232 in arb. units

    T1/u3 = 170
    T2/u3 = 26.8
    T3/u3 = 162
    T4/u3 = 55.0

    Run 2233 (Y = +1 mm)
    T1/u3 = 170
    T2/u3 = 27.0
    T3/u3 = 162.2
    T4/u3 = 54.1

    So, the trigger rates normalized to beam current didn't change.

    Waiting for beam... want to make bigger Y changes and some X ....

    FIGURE 1