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    User name Ulmer

    Log entry time 18:42:44 on October27,2002

    Entry number 89142

    keyword=1H(e,e'p) Elastic cross sections

    Preliminary analysis of two 1H(e,e'p) runs at different kinematics was done and comparisons to MCEEP have been made. Run 2580 was part of the epscan to find the spectrometer angle offsets. This run was at Q^2=4.35 GeV^2. Run 2787 was at the f00 kinematics (Q^2=3.50 GeV^2).

    

    
                             Run 2580        Run  2787
    

    
  current                     18 uA             84 uA
    
  ratio to MCEEP     91.4%            83.1%
    
  corrected ratio        92.7%            88.7%
    

    
Here, "corrected ratio" assumes a boiling correction of 8% at 100 uA and linear with current.  All numbers have been corrected for CDT and "tracking efficiencies" in the VDCs (i.e. fraction of events passing multiplicities).  Further, the combined correction factor amounts to (T5-EDTM)/(Good in VDC), where EDTM is calculated by assuming 3 Hz over the course of the run.  Finally, for Run 2787, I integrated the missing energy spectrum to 30 MeV to avoid punch throughs.  I neglected to do this for Run 2580, but they appear to be a very small fraction of the events.
    

    
So, there is about 4% difference between the two runs and we are roughly 10% below expectations.  No corrections for detector efficiencies have been made.