Study of charge reconstruction for high energy electrons using geometry UPGR12
Updated: Wed Jan 10 09:43:10 EST 2007

All plots on this page are produced for a single electron events with pT of 30 GeV/c.

  1. Input: one-electron events.
    Generated electrons have fixed pT and zVertex of -30, 0, or +30 cm, and uniform 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.
    GEANT hits were used as input and smeared with resolution as shown in the table below.
    detector assumed resolution weight of the point Remarks
    vertex 200 mu m in X,Y,Z W=1/(200 mu m)^2 added as a hit
    FST 20 mu m in X,Y
    10 mu in Z
    W=1/(20 mu m)^2 4 disks (see plot)
    numbered 1,...,4
    FGT 60 mu m in X,Y
    10 mu in Z
    W=1/(60 mu m)^2
    TPC 1 mm along arc
    1 mm in Z
    W=1/(1mm)^2 * drop padrow #1 and #13
    * drop hits at |Z|>197 cm
    Endcap SMD
    mock hit *)
    2 mm in X,Y,Z W=1/(2 mm)^2 at xPoint of Geant helix
    w/ SMD plane
    *) Based on SMD response study by Jim

  3. The following detector configuartions have been considered
    Config Prim
    TPC Endcap
    A yes all all yes yes
    B yes - - yes yes
    C yes - - yes -
    D yes 1+4 1+3 yes yes
    E yes - 1+3 yes yes
    F yes all all yes -

    Further configurations added on January 16,2007
    Config Prim
    TPC Endcap
    G yes 1+4 1+3 all no plots here
    H no 1+4 1+3 all yes plots here
    J no all all all yes

  4. Each of the detectors provide different # of fit points depending on zVertex, eta, and selected configuration.
    detector Configurations
    FST all 4 disks, config=A,F,J
    only disks 1+4, config=D,G,H
    config=B,C,E : no
    FGT all 4 disks, config=A,F,J
    only disks 1+3, config=D,E,G,H
    config=B,C : no
    TPC config=A-J
    E-SMD config=A,B,D,E,H,J
    config=C,F,G : no
    vertex config=A-G : yes config=H,J : no

  5. Quality of the reco 3D tracks (fit of circle+line) is defined based on a difference of the reco direction of primary track at the vertex vs. Geant track direction.

    Charge reco efficiency is defined as the ratio of # of generated electrons to # of reco tracks w/
    * nFitP>=5, including vertex as a hit
    * delPhi<3 mrad
    * delTheta <3 mrad
    * the sign of the reco charge is correct
    Note, 3 mrad translates to 1cm displacement of reco track vs. projected ideal helix at the Endcap SMD plane (Z~300cm).
    No cut on reco pT is imposed.

  6. Resulting charge reco efficiency for electrons w/ pt=30 GeV/c.
    Primary vertex & TPC are used in all configurations. Statistical error of efficiecny is of 0.01 to 0.02.
    Config A, FST=all, FGT=all, ESMD=yes
    Config F, FST=all, FGT=all, ESMD=no
    Config D, FST=1+4, FGT=1+3, ESMD=yes
    Config E, FST=no, FGT=1+3, ESMD=yes
    Config B, FST=no, FGT=no, ESMD=yes
    Config C, FST=no, FGT=no, ESMD=no

  7. Conclusions about reco of the charge of the high pt track
    1. reduction of # of FST,FGT disks to 2 causes moderate losses of ~10% for eta in[1.2,2.0] (compare config A vs. D)
    2. Missing FST affects tracks at eta > 1.7 (compare config D vs. E)
    3. having FST and FGT in any form (2 disks each) would extend charge reco from eta<1.5 to eta <2.2 (compare config D vs. B)
    4. SMD point does not help much if FST & FGT are in (compare config A vs. F)
    5. SMD point added to current tracking (no FST, no FGT) should extend reco from eta <1.2 to eta<1.5 (compare config C vs. B)

    Used macro pl3Z.C