Z Vertex distribution data from Wlodek

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Z Vertex distribution (data from Wlodek)
Vertex z-average gt 0 ??
x-axes in cm
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Fitting the Vertex distribution (data)

• The collision vertex (Gaussian) distribution is
  convoluted by an additional Gaussian due to
  timing resolution
• where G(x-?,?) e-(x-?)2/(2?2), i.e., Gaussian
• V(z)

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Fitting the Vertex distribution (data)
Vertex z-average gt 0 ??
(cm)
Discontinuity due to trigger cut (10 ns) included
in the fit
(cm)
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What it looks like if we run the same MC program
twice under the same conditions ??
t ( GeV/c2 )
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New things in the simulation

• Additional Gaussian smearing with ? of 36 cm in
  addition to the vertex Gaussian and this is
  applied at the reconstruction stage of the Monte
  Carlo
• A cut at the ve side of the z vertex 92 cm is
  applied to the vertex (without the timing
  resolution).

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Ratio of (Old acceptance)/(New acceptance)
1.04
t ( GeV/c2 )
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