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    User name Armstrong

    Log entry time 06:12:09 on June22,2004

    Entry number 126625

    keyword="empty" target test started

    B  eam has tripped and will be off for a few minutes, so
    we have ended run 2365, and are going to use the time to
    bleed off most of the 44He from the target;
    the idea(s) being to take some data with only around 2 atm. 
    (vs. the 13 atm we have been running recently) in the racetrack
    cell, and see 
      a) does septum heating scale properly with reduced radiation
        length (how much of the heating comes from the He and how 
        much from target windows and possibly other material)
      b) do the detector rates and lumi rates (as measured both
        by the ADC amplitudes  and the asymmetry widths) scale in
        a sensible manner with the reduced He density, or are 
        possibly the target windows thicker than we think - this 
        is the oddest way I have ever measured the thickness of an
        Aluminum window!
      Present target conditions after bleed off:
        T_1 = 7.0 K
        T_2 = 7.0 K
        T_3 = 8.0 K
        cell pressure = 39.5 psi (2.7 atm)
        High power heater = 338 W,  CHL flow 16 g/s
           (28 µA of beam)
        start HAPPEX DAQ run 2366