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
    W=1/(1mm)^2 drop padrow #1, #13
    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

    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
    * delPhi<3 mrad
    * delTheta <3 mrad
    Note, at the Endcap SMD plane (Z~300cm) 3 mrad translate to 1cm displacement of reco track vs. projected ideal helix.

  7. Charge reco efficiency requires additional the sign of the reco track is correct. No cut on reco pT is imposed.
    Pt=20 GeV/c Pt=40 GeV/c

    Used macro pl3Z.C