A collection of SVT plots from Fall 2001 special runs

Mass distribution in the D0 region, after SVT i.p. cuts (online quantities only)

In order to calculate masses, SVT tracks are matched in phi with COT tracks (from L3 reconstruction); a hybrid track is formed, with impact parameter from SVT, and all other parameters from COT.

  • Mass plot

  • SVT - COT Matching cuts:
  • q1*q2 < 0.
  • chi2_1(SVT), chi2_2(SVT) < 10.
  • 100 µm <|d1(SVT)|, |d2(SVT)|< 1 mm

  • |Z01(COT)-Z02(COT)|<5.0 cm

  • Pt(D0)>3.0 GeV/c
  • DeltaPhi<135 deg
  • -100 µm < Lxy(D0) < 3.0 cm (solid)
  • -3 cm < Lxy(D0) < -100 µm (dashed)

    Both mass assigments enter the plot; in most cases they differ only slightly. Total number of triggers entering the plot is about 600,000.

    Beam profile with the SVT (sigma=48µm)

    Distribution of SVT measured impact parameter in run 127844, in a single wedge (b3, w3) , after subtracting the beam position. There are no corrections for internal detector misalignments.

    This can be compared with the prediction from simulation of SVT on real data from run I, giving sigma=45µm. This width contains two contributions: a Tevatron beam width of ~28µm and an impact parameter resolution ~35µm

    Comparison of SVT parameters with Offline parameters

  • Plot of d(SVT) - d(offline).
    This is done offline by phi-matching SVT tracks to offline tracks with algorithm=11 (OutsideIn3D, v4.0.0). Both impact parameters are 'raw', i.e. they have no beam subtraction. Cuts are listed on the plot. The sigma is ~23 µm.

  • Other parameters
    This shows differences in phi and curvature.

    Ks signal from SVT i.p. cuts

    In order to calculate masses, SVT tracks are matched in phi with COT tracks (from L3 reconstruction); a hybrid track is formed, with impact parameter from SVT, and all other parameters from COT.

  • Mass distribution of track pairs from special runs, using official L1 and L2 selection for hadronic Bs trigger, but no i.p. cuts.

  • Mass distribution with d and Lxy cuts. A clear Ks peak is seen. Note that there is an intrinsic upper limit to impact parameter (2mm) due to SVT acceptance. These Ks belong to the small fraction that underwent an early decay.

  • Enlarged view of the above. The dotted line is for backward decays (Lxy<-500µm)

    You may also want to look at the following:

  • Lxy distribution below the Ks peak

  • Lxy distribution in Ks sidebands