First Look on 900GeV Inner
Detector Tracks in Atlas
E. Gross, G. Mikenberg, O. Silbert
Acknowledgment: Nir Amram (TAU)
Chi2 distribution
p-value distribution
• Following Alexander
Milov Suggestion to
look at p-values
• Since any cumulative
probability (p-values) is
distributed uniformly –
a way to make the same
selection for all degrees
of freedom
Bad
estimation
of the
errors
p-values distribution
Vertex
xvertex  0.18mm
yvertex  0.99mm
d 0  pT  r / pT 
 r sin   0 
xvertex   r cos 0
yvertex  r sin 0
xvertex  0.1891mm
yvertex  0.9978mm