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Open charm simulations ( D + , D 0 ,  + c )

Open charm simulations ( D + , D 0 ,  + c ). I.Vassiliev , S.Gorbunov, I. Kisel, S. Seddiki and I. Sevastiuk CBM Collaboration Meeting 26-Sep-07. Sts geometry: 2MAPS +6strip (Strasbourg geo) or 2M2H4S (D+ and D - at 25AGeV);

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Open charm simulations ( D + , D 0 ,  + c )

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  1. Open charm simulations (D+,D0,+c) I.Vassiliev, S.Gorbunov, I. Kisel, S. Seddiki and I. Sevastiuk CBM Collaboration Meeting 26-Sep-07 • Sts geometry: 2MAPS +6strip (Strasbourg geo) or 2M2H4S (D+ and D- at 25AGeV); • TOOLS: signal (D+K-+ +; +cpK-+and D0K-+ +-) , and background (central UrQMD) simulation; 15,25,35 AGeV; Pythia signal generator by D.Bertini; • Tracking (fast), • Primary Vertex Reconstruction, • Background study. Cuts optimization. S/BG ratios; • D+K-+ +; D0K-+ +- and +cpK-+ reconstruction; • Summary & plans

  2. CBM (light) setup Sts + TOF 8 stations (10,20,30,50,62.5,75,87.5,100 cm) 2 first in vacuum Topology: stations 1,2 – MAPS, 3-8 – Strips or (3,4Hybrids) "MAPS" (150m), first two station with 10x10m cell size "Strip"-detectors (400m), 50m strip-pitch, ½ strip length; Realistic hit producers sts_digi_new_standard-3.par

  3. MAPS + strips: 96.23 ± 0.09 (D+) MAPS +strips: 92.87 ± 0.14 efficiency [%] momentum [GeV/c] Tracking in STS Algorithm: “Cellular Automaton + Kalman Filter” by I.Kisel Tracking efficiency: 697 rec. tracks~ 1% ghost tracks all rec. tracks primary tracks (signal) central collision Au beam, 25 AGeV, on Au target Momentum resolution: ~ 1% 78 ms on Pentium 4

  4. primary vertex reconstruction sv K- + pv - + 5.7 µm zmc-zreco (cm)

  5. + c D+K-+ +; +c pK-+and D0K-+ +- z-vertex reconstruction D+K-+ + sv K- old p pv + new

  6. Strategy: background suppression keeping maximum of efficiency single track parameters based cuts: • χ2primon the impact parameter (lower value) 4.5-6.5 • IP impact parameter cut (upper value) 1mm • track momentum cut p > 1.0 GeV/c • track transverse momentum pt > 0.25 GeV/c multiple track (particle) parameters based cuts: • χ2GEOgeometrical constrained fit 3.0 • χ2TOPO topological constrained fit 2.0

  7. central UrQMD Background study; tracks y zR xR x z

  8. Cut optimization D+K-+ + @ 25 AGeV χ2primon the impact parameter (lower value) S/B

  9. Cut optimization D+K-+ + @ 25 AGeV 1k central UrQMD  ~2.8x1015 “triplets" χ2prim > 6.5 , pt > 0.25 GeV/c, p > 1 GeV/c, Ip < 1 mm : 1k central UrQMD  ~108 “triplets" after the cuts

  10. Background study, tracks and vertices cτD+ = 312 m cτD0 = 123 m cτ+ = 59 m c

  11. D+->K- ++geometrical and topological constrain

  12. Cut optimization M = 4.17 ·10-5 BR = 9.51 % χ2 = 5 σ Eff = 5.47 % S/B 2σ = 1.33 D+ = 20.7K per 1011central ev. S/B Efficiency χ2 = 9 σ Eff = 2.5 % S/B 2σ = 42.4 D+ = 10.8K

  13. D+ ->K-π+π+all cuts 25AGeV 2m2h4s 2m6s Eff = 1.84 % S/B 2σ = 1.4 7.1K D+ per 1011 central events M = 4.17 ·10-5 BR = 9.51 % 16K D+/1011 central ev.

  14. D+ ->K-π+π+ at 35 and 15 AGeV M = 2.67 ·10-4 BR = 9.51 % Eff = 5.64 % S/B 2σ = 15.6 D+=135K per 1011 central ev. M = 3.34 ·10-7 BR = 9.51 % Eff = 1.97 % S/B 2σ = 0.5 D+=62 per 1011 central ev. 15 AGeV 35 AGeV

  15. D0 ->K- - ++ topological constrain

  16. D0 ->K- - ++ (25 AGeV) 8.1109central events (300 central UrQMD) 3.2K D0 + 1K D0 per 1011 central events Systematic!

  17. + pK-+ c M<y=1> = 4.88·10-4 (A.Andronic) BR = 5% 10.7(4.4) K c+ per 1011 central events

  18. Summary and plans Fast (SIMDized) CA tracking works fine; D+K-+ +; +cpK-+ and D0K-+ +- looks very promising for the CBM experiment: collection rates about 16K D+, 32K D-, 3.2K D0, 1KD0, 4.4K+c per 1011 at 25 AGeV with excellent S/B ratio; next steps: More realistic Sts (cables and support structures) TOF particle ID including K-(+) identification; Ds detection possibility study; Open charm common trigger feasibility study.

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