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Λ reconstruction in the magnetic field. Evgeny Kryshen (PNPI, SPbSPU). 10 000 ce ntral Au-Au collisions at 25 AGeV U r QMD generator CBMROOT framework OCT04 Magnetic field v03b Strip hits with 10 μ m resolution No particle ID Ideal track finding (more than 3 MC points) - PowerPoint PPT Presentation

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  • reconstruction in the magnetic fieldEvgeny Kryshen(PNPI, SPbSPU)

    Simulation meeting

  • 10 000 central Au-Au collisions at 25 AGeVUrQMD generatorCBMROOT framework OCT04 Magnetic field v03b Strip hits with 10 m resolutionNo particle IDIdeal track finding (more than 3 MC points)Momentum and vertex reconstruction with Kalman filter (4-order Runge-Kutta extrapolation in magnetic field)Simulation framework

    Simulation meeting

  • Acceptance for Total acceptance STS: 15.8%Initial distributionAcceptance

    Simulation meeting

  • Momentum fit performance

    Simulation meeting

  • Secondary vertex fit performanceZ-vertex resolution: 340 mMomentum resolution: 0.64%Invariant mass resolution: 0.78 MeV0.86 MeV for 1% momentum resolution assumption1.3 MeV for parabolic approximation (TSR)

    Simulation meeting

  • Applying cutsThe following variables were considered to cut the background:

    bpp impact parameter of accepted particlespca z position of secondary vertexdca distance of closest approachbla impact parameter of pair momentum

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  • Impact parameter of daughter candidatesPositively charged particlesNegatively charged particles

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  • Vertex parametersZ position of the fitted vertexDistance of closest approach

    Simulation meeting

  • Pair impact parameter (bla)

    Simulation meeting

  • Selection of the first cutConclusion: impact parameter cut is the strongest one

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  • Selection of the second cut

    Simulation meeting

  • Selection of the optimal cut value

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  • Invariant mass spectra

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  • Reconstruction of initial distributionsCorrected signalInitial distribution

    Simulation meeting

  • Reconstructed pT distributionsy = 1.0 1.2y = 1.8 2.0

    Simulation meeting

  • Reconstructed rapidity spectrumInitial yield: 40.46Reconstructed: 40.30

    Simulation meeting