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Tracking issues for hyperon simulations

Tracking issues for hyperon simulations. Evgeny Kryshen (PNPI, SPbSPU). Secondary track finder performance. Track finding performance measured by CbmStsFindTracksQa Conditions: central, 25 AGeV, 2hybrids+4strips, 5 degree stereo angle. Sec. finder vs CA (isec 2):

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Tracking issues for hyperon simulations

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  1. Tracking issues for hyperon simulations Evgeny Kryshen (PNPI, SPbSPU)

  2. Secondary track finder performance Track finding performance measured by CbmStsFindTracksQa Conditions: central, 25 AGeV, 2hybrids+4strips, 5 degree stereo angle Sec. finder vs CA (isec 2): 30 times better time performance, lower ghost rate, 50% higher sec. track efficiency 6.5 Lambda/event before cuts (~2Lambda in the note) CBM STS meeting, 15 February 2007

  3. Secondary vertex fit options Topological constraint Ordinary fit Refit of secondary vertex – first estimate for the vertex position is used as a starting point for the secondary vertex fitter Ordinary fit: σ = 1.78 MeV Topol. fit: σ = 2.40 MeV Refit of SV: σ = 1.42 MeV Refit of tracks +SV: σ = 1.41 MeV Proton refit – positive tracks are refitted with the proton PID assumption Refit of sec. vertex + proton refit Refit of sec. vertex Conclusion: refit of the secondary vertex helps much in the hyperon case, proton refit gives no gain in the invariant mass resolution CBM STS meeting, 15 February 2007

  4. Vertex resolution Distance of closest approach Distance of closest approach: No refit <DCA> = 0.0563 cm With refit <DCA> = 0.0397 cm ΞΛΩ Vertex error in z: No refit: σ = 4.1 mm With refit: σ = 3.2 mm With refit No refit Vertex error in z direction No refit With refit CBM STS meeting, 15 February 2007

  5. Results on hyperons 25 GeV Ω Ξ Λ 6 GeV Ω Λ CBM STS meeting, 15 February 2007

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