The attached file shows five dot plots.  These represent the
beam profile at dc plane 1 (z=-49.8cm), as reconstructed using
straight line fits.  In each plot, the horizontal axis is U,
while the vertical axis is V.  The plots are arranged as follows:
                
                1823_s3    1856_s4   1823_all
                1857_s4    1858_s4

where "18xx" indicates the run number, "_all" means there is no
cut on the data plotted, and "_sx" means there is a requirement
that scintillator "x" (either 3 or 4) fired.  In the case of no
cut, the profiles for all runs look similar, so I just show 1823
as typical.  For runs 1856 and 1857, I understand from Nate that
scintillator 4 was a small counter positioned downstream or
upstream of the detector, offset in x and y.  If someone can
tell me what that x and y position was, we will be able to relate
the X-Y and U-V coordinate systems.  For runs 1823 and 1858, it
looks from the plots that s3 and s4 were connected to large
(20x20 cm?) square counters, roughly centered, but not in the
trigger.
  For the record, here are the rough centroids of the distributions:

              Run       U(cm)    V(cm)
             1823_s3      1       -1
             1856_s4     -2        7
             1857_s4      0       10
             1858_s4     -2       -2

Description: gzipped dot plots , Filename: scints.ps.gz

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