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    User name R. Michaels

    Log entry time 02:02:58 on October28,2005

    Entry number 158219

    Followups:

    keyword=Aluminum backgrounds

    Aluminum dummy target runs with HAPPEX and spectr. DAQs
    ========================================================

    Most recent LH2 HAPPEX DAQ production run 5940.
    Switched to Alum. 20 cm dummy target and take run 5941

    Online results for ratio detN/bcm1 (N=1,2,3,4) with cut on bcm1
    to define beam "on".

    Run 5940 (LH2 production)
    det1/bcm1 = 2.54
    det2/bcm1 = 2.38
    det3/bcm1 = 2.50
    det4/bcm1 = 2.36

    Run 5941 (20 cm Alum dummy)
    det1/bcm1 = 0.130
    det2/bcm1 = 0.138
    det3/bcm1 = 0.120
    det4/bcm1 = 0.149

    I think the "xt" factor is 0.125. This is the ratio of the thickness
    of aluminum in the LH2 target to the alum of the 20 cm dummy.
    So, this implies backgrounds (HAPPEX DAQ):
    det1 = 0.64 %
    det2 = 0.72 %
    det3 = 0.60 %
    det4 = 0.79 %

    Go to 0.6 microAmp beam (a bit low for Alum but we want same current for both targets). Switched to spectrometer DAQ. Did checklist.
    Here are raw online rates (looking at xscaler++ stripcharts):
    Left arm det1 = 4280 Hz
    Left arm det2 = 13800 Hz (ratio of det rates = 3.22)
    Right arm det1 = 8550 Hz
    Right arm det2 = 8750 Hz (ratio of det rates = 1.02)
    T1 = 58.4 kHz
    T2 = 17.2 kHz
    T3 = 47.5 kHz
    T4 = 17.5 kHz
    T5 = T6 = 0
    T7 = 109 kHz
    T8 = 82 kHz

    Spectr. DAQ run 2908 - 2910 with Alum. dummy.
    Run 2908 and 2909 have 50K events. Wrestle with runcontrol
    to set event limit. Set it to infinite. Run 2910 is fine,
    it has 1.01 M events.

    Now go back to LH2 target. Still 0.6 uA
    Rates from xscaler
    L-arm det1 = 81.5 kHz
    L-arm det2 = 228 kHz
    R-arm det1 = 124.5 kHz
    R-arm det2 = 171 kHz
    T1 = 369 kHz
    T2 = 288 kHz
    T3 = 343 kHz
    T4 = 292 kHz
    T5 = T6 = 0
    T7 = 418 kHz
    T8 = 462 kHz
    (note, T7 and T8 didn't scale as much)

    Run 2911 with LH2 target and 0.6 uA.
    Next we do run 2912 with same conditions except beam = 0.2 uA
    (lower rate -> better for Qsq; however, feedback stops working too
    and no stripline data below approx 0.5 uA).

    Here are ratios of detector to bcm for counting mode, using scalers.
    A cut on u10 (bcm with x10 gain) to define beam "on".
    Run 2910
    L-arm det1/u10 = 0.575
    L-arm det2/u10 = 1.85
    R-arm det1/u10 = 1.15
    R-arm det2/u10 = 1.18

    Run 2911 with LH2 target and same beam
    L-arm det1/u10 = 10.9
    L-arm det2/u10 = 30.3
    R-arm det1/u10 = 16.5
    R-arm det2/u10 = 22.8

    Implying backgrounds (same "xt" as above)
    L-arm det1 = 0.66 %
    L-arm det2 = 0.76 %
    R-arm det1 = 0.87 %
    R-arm det2 = 0.65 %

    Fairly good agreement but don't ask me the mapping between
    HAPPEX DAQ detector numbering and spectr. DAQ numbering so
    early in the morning.