Study of track & charge reconstruction for high energy electrons using geometry UPGR12

All plots on this page are produced for a single electron events with pT of 20 GeV/c.

1. Input one-electron events.
Generated electrons have fixed pT and zVertex of -30, 0, or +30 cm,and flat eta and phi distribution. Sample of high pT electrons thrown from different zVertex location over eta range [1,2] are shown here: Z=-30cm , Z=0cm , Z=+30cm.,

2. Assumptions about resolution of detectors. Positions of GEANT hits were smeared with resolution...
Table 1.
detector assumed resolution weight of the point Remarks
FST,FGT 60 mu m in X,Y
10 mu in Z
W=1/(60mu m)^2 4 disks
TPC 1 mm along arc
1 mm in Z
drop hits at |Z|>197 cm
vertex 200 mu m in X,Y,Z W=1/(200 mu m)^2 added as a hit

3. # of available hits from FST,FGT, and TPC as function of pseudrapidity (X-Axis)
and assumed Z-vertex position ( red=- 3cm, green=0, blue= +30 cm)
detector # of hits vs eta
FST
FGT
TPC
all+
vertex

5 hits limit to find the helix is marked by the red line

4. Chi2/DOF for Circle fit vs. eta, separate for 3 Z-vertex locations.
Note, DOF changes w/ eta (see above) so the shape of chi2/DOF changes as well.

5. Quality of the reco 3D tracks (fit of circle+line) can be measured as a difference of the reco direction of primary track at the vertex vs. Geant direction. I choose angles: theta & phi, in radians.

6. Track reco efficiency is defined as the ratio of geant electrons to # of reco tracks w/
* nFitP>=5, including vertex as a hit