Hadron Alley Conditions (Jose A. Hernando)

  • calMatchChi2 cut: chi squared of the match between Velo(2D,3D) tracks and L0 Calo cluster.
    • computed as: i) unbias sample (L0 hadron) from the distribution of chi2 of the matching Velo tracks - L0 Calo object, and select cut to accept few tracks per event; cross check this matching with a matching with T segments starting with L0 Calo Clusters. ii)From unbias sample (L0 hadron) and offline reconstructed, use offline tracks to decide when the trigger tracks has been properly matched to the L0 Calo object and decide on the cut accordingly.

  • rIP cut (minimum impact parameter cut between 2D Velo Tracks with respect any 2D Primary Vertices)
    • computed as: unbias sample (L0 hadron) using RZ tracks and 1 PV events, the value that will select a small fraction (~5%) of tracks.

  • IP cut (same as before but with 3D tracks)
    • computed as: in 3D. similar to 2D, the cut will select a small maybe larger (10%) of the tracks.

  • DOCA cut (Distance of closest approach between two tracks (3D))
    • computed as: the distance of closest approach of 2 tracks from the same vertex, using J/Psi or any two traks coming from the Primary Vertex.

  • Pt1, Pt2 cuts (for prettrigger and for trigger, so 4 cuts in total.)
    • computed as:
      • unbias sample: from the distribution of Pt, balance time and rejection. If forward reconstruction available, compare Pt using and not using TT. Compare of matching forward from Velo tracks and backwards from tracks mades with T segments.
      • sample muon alley: compare with pt of long track muon, and use velo TT of this muon to study selection efficiency and VeloTT resolution.

  • Dz cut: required distance in z between the secondary vertex and the primary one.
    • computed as:

  • fc (Pointing) cut: fc = Pt'/(Pt+Pt1+pt2). Pt' is the projected momentum of the combined 2 tracks that makes a secondary vertex, into the plane which normal is defined by the direction between the primary vertex and the secondary one. Pt1 and Pt2 are the Pts of the tracks of the secondary vertex
    • computed as: The pointing of 2 tracks (expected from a b decay) with respect the PV. tentative computation: use muon sample, use tracks above a given Pt,IP to make vertices with the muon and compute pointing with them. unbias sample, use tracks above a given Pt and below an IP window to compute the fc for the background and compare with the ones with the muon sample.

Hadron Alley Summary Box Contents

  • Quantities:
    • CALMATCHCHI2 : Chi2 match of the velo track and L0 Calo Candidate
    • H1PT : Pt of the track with largest Pt
    • H2PT : Pt of the second track with largest Pt
    • H1IP : IP of the track with largest Pt
    • H2IP : IP of the second track with largest Pt
    • DOCA : DOCA of the secondary vertex.
    • DZ : Distance in z between the secondary and primary vertex
    • FC : Pointing variable of the secondary vertex
    • NTRACKS : considered to take the decision
    • NVERTICES: considered to take the decision

note : the secondary vertex will the one with highest Pt among the selected.

  • Objects:
    • All tracks above the Pt tresholds and in the IP windows
    • All 2 track vertices that fulfill the secondary vertex criteria

Hadron Alley Monitoring

  • All box quantities, can be done in a external monitoring algorithm (in EFF or MF)
  • Chi2 distributions for the Velo and L0 calo candidates (collected histo in EFF)
  • IP distributions for Velo 2D and 3D (collected histo in EFF)
  • Common quantities: number of tracks and vertices, 2D,3D,VeloTT,Forward, in a IP window, etc.

L0 Confirmation

* A description of the L0 Hadron confirmation using the HCAL and Tstations can be found here

-- MiriamGandelman - 17 May 2006

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Topic revision: r7 - 2007-10-29 - StephenWotton
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