[G14_run] Equivalent "empty cell"

[Dr. A.M. Sandorfi]

g14 folks,
A few points regarding subtracting an "equivalent empty cell":

-I've tracked down some more info on things in the path of the beam and
updated the attached vertex Z file.
- I've folded the Gaussian distribution of the beam from the radiator and
through the 2.6 mm OD collimator, and found a flux-weighted effective area
on the target cell of 68.13 mm^2. The effective active mass of aluminum in
the beam is then 0.1145 gm, and were this all packed into a single foil,
it's thickness would be 622 microns.
- this leads to the following vertex-z separation of events:
  Full cell (HD + cell): Y[-12.5 < z < -1.5]
  Equivalent empty cell: Y[-1.5 < Z < +8.0] + (6.25)*Y[+12.0 < z < +21.0]

So far missing mass histograms have been constructed with just a z cut on
the interior of the target cell [-10 < z < -6]. It would be interesting to
try constructing them from the difference of two histograms with the above z
cuts. Paul, could you try this?

Finally we should keep in mind that there is a long (40 cm) 0.85 tesla
magnet surrounding the target. Quick estimates suggest it doesn't do much to
the tracks, but maybe there is some distortion for far forward or backward
angles.

Andy


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