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    User name Armstrong

    Log entry time 06:34:16 on June22,2004

    Entry number 126627

    keyword=septum heating

     After a 20 minute long beam trip, the starting septa temps
       Left  upper coil:  6.10 K
             lower coil:  6.25 K
       Right upper coil:  6.60 K
             lower coil:  6.35 K
    With the present situation, we have roughly the same radiation
    length from the remaining 4He gas as from the
    target windows (0.57% each), for a total of 1.15%. 
       (compared to 3.34% for the full He cell, and 2.25% for
    the dummy target).
      after 25 minutes of fairly steady beam we have 
       Left  upper coil: 6.25 K
             lower coil: 6.35 K
       Right upper coil: 6.80 K
             lower     : 6.50 K
      So, net heating at 28 µA is .15 K (right arm) and 
        0.10 K (left arm). Compare to full cell, where heating
        at this current was  (last night) 1.0 K (right arm) and
        0.70 K (left arm);  ratios of heating is a factor of 7.
        This is roughly the ratio of the He densities between 
        the full and empty cell (factor is more like 5), while
        the radiation lengths including the walls is only a factor
        of 3.
      Conclusion: The He causes most of the septum heating, there 
        is no evidence for "extra heating" from the cell materials.