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Muon identification with realistic detector layout

10th CBM Collaboration Meeting. Muon identification with realistic detector layout. Anna Kiseleva. Outline. Realistic segmentation of the MuCh Invariant mass spectra for LMVM and charmonium Time of flight measurements J/ ψ and Ψ ' at 35 AGeV Conclusions Next steps. Simulations.

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Muon identification with realistic detector layout

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  1. 10th CBM Collaboration Meeting Muon identification with realistic detector layout Anna Kiseleva

  2. Outline • Realistic segmentation of the MuCh • Invariant mass spectra for LMVM and charmonium • Time of flight measurements • J/ψ and Ψ' at 35 AGeV • Conclusions • Next steps

  3. Simulations • Signals (Pluto, multiplicities from HSD): • ρ, ω, φ, η and ηDalitz • J/ψ, Ψ' • Background (UrQMD): • central Au+Au at 25 and 35 AGeV (charmonium) • Statistics for background: • 20k events

  4. Detector parameters • STS: • 6 strip detectors • MuCh: • 15 (18) layers with realistic segmentation • Layer 12: ToF RPC - 80 ps time resolution • ToF at 10 m: • 0.7 cm position resolution • 80 ps time resolution STS MuCh ToF

  5. Muon Chambers (MuCh): GEANT3 20 20 20 30 35 cm hard track Fe Fe Fe Fe Fe 314 cm soft track 5 cm 0 cm 102.5 cm

  6. Muon system at CBM Sergey Belogurov

  7. Muon system at CBM Sergey Belogurov

  8. Segmentation of MuCh See talk of Mikhail Ryzhinskiy layer Nr.1 max 1 hit/(cm2×event) min pad 1.4  2.8 mm2 layer Nr.15 max 0.01 hit/(cm2×event) max pad 44.8  44.8 mm2

  9. Results large 1m Fe MuCh for measurements of: low mass vector mesons charmonium compact  background signals ρ ω φ η ηDalitz Central Au+Au collision at 25 AGeV S/B Efficiency Mass ratio (%) resolution (MeV) ω0.08 3.7 12 4.7* 10 φ 0.03 6 19 8.3 12 ρ 0.001 2.7 9 3.8 J/ψ 7 16 3620 24 Ψ' 0.09 19 41 28 Accepted signals (MC)*  background signals  J/ψ Ψ' *LMVM: ≥ 4STS + 15(12)MuCh charm:≥ 4STS + 18MuCh *smearing 100μm

  10. Reconstructed ρ0: hh+hs pairs

  11. Reconstructed charmonium J/ψΨ'

  12. Background suppression for J/ψ(Ψ') efficiency central Au+Au collisions at 25 AGeV

  13. Reconstructed background large MuCh —μ —π —Κ —ghost particle ID: ≥ 70% true hits

  14. Reconstructed background compact MuCh hard tracks soft tracks —μ(106 MeV) —π(140 MeV) —Κ(498 MeV) —p(938 MeV) —ghost particle ID: ≥ 70% true hits

  15. Mass calculation 1 P2 β2 m2 = m2 = P2 ( - 1) β = γ = (β × γ)2 L c × t 1 √1 – β2 (L, t) → βToF layer Nr.12 ToF RPC ToF (L, t) → βMuCh

  16. Mass distributions PSTSvs.m2 ToF at MuCh layer Nr.12 ToF at 10m

  17. Mass distributions PSTSvs.m2 soft tracks ToF at MuCh layer Nr.12 signal μ bg μ π K p ghost

  18. Mass distributions PSTSvs.m2 hard tracks ToF at MuCh layer Nr.12 signal μ bg μ π K p ghost

  19. Mass distributions c hard tracks rescaled ToF at MuCh layer Nr.12 signal μ bg μ π K p ghost

  20. Mass distributions PSTSvs.m2 hard tracks cut at MuCh ToF ToF at 10 m signal μ bg μ π K p ghost

  21. Reconstructed background after cuts hard tracks soft tracks —μ(106 MeV) —π(140 MeV) —Κ(498 MeV) —p(938 MeV) —ghost particle ID: ≥ 70% true hits

  22. Results: hh pairs ──────────cuts ────────── 1 2 1+2 layer Nr.12 ToF at 10m ToF RPC without cuts — S/B ratio ———————————————————————————————— ω φ ω φ 0.09 0.03 2.0 4.1 0.11 0.05 1.6 3.4 0.17 0.06 1.5 3.0 0.21 0.08 1.2 2.5 — Efficiency (%) ——————————————————————————————

  23. Results: hs pairs hard tracks: cuts at layer Nr.12 ToF RPC + ToF at 10m soft tracks : cuts at layer Nr.12 ToF RPC without cuts — S/B ratio ———————————————————————————————— ω φ ω φ 0.08 0.02 1.7 1.9 0.18 0.09 1.1 1.2 — Efficiency (%) ——————————————————————————————

  24. Results (hh+hs pairs)  background signals ρ ω φ η ηDalitz Central Au+Au collision at 25 AGeV S/B Efficiency ratio (%) ω0.08 0.16 3.7 2.3 φ 0.03 0.08 6 3.9 ρ 0.001 0.002 2.7 1.6 reconstructed after bg pairs/event: cuts hh 1.4×10-23.8×10-3 hs 1.8×10-2 5.5×10-3 after cuts after cuts  background signals ρ ω φ η ηDalitz

  25. Reconstructed ρ0: hh+hs pairs without cuts after cuts

  26. Reconstructed ρ0: hh+hs pairs without cuts after cuts

  27. Mass distribution for charm PSTSvs.m2 ToF at 10 m signal μ bg μ

  28. Reconstructed background after cuts —μ —π —Κ —ghost particle ID: ≥ 70% true hits

  29. Background suppression for J/ψ(Ψ') efficiency central Au+Au collisions at 25 AGeV S/B 7 S/B 0.09 after mass cut S/B 15 S/B 0.13 after mass cut

  30. Reconstructed charmonium after mass cut J/ψΨ'

  31. Invariant mass spectrum ■with mass cut central Au+Au collisions at 25 AGeV

  32. Charmonium at 35 AGeV PSTSvs.m2 ToF at 10 m signal μ bg μ

  33. Background suppression for J/ψ(Ψ') efficiency central Au+Au collisions at 35 AGeV S/B 11 S/B 0.17 after mass cut S/B 20 S/B 0.22 after mass cut

  34. Invariant mass spectrum ■with mass cut central Au+Au collisions at 35 AGeV

  35. Conclusions • Promising results for low-mass vector mesons using realistic segmentation of Muon System • Good result for J/ψ • ψ' identificationpossible • Good background suppression using time measurements

  36. Next steps • Improvement of muon tracking • Detector layout study (size, position resolution, type of detectors) • Optimization of number of detector layers • Decrease number of hits at ToF using pipe shielding and extended absorber

  37. Rvertexvs.Zvertex of tracks hits/event

  38. pipe shielding + extended absorber W

  39. Rvertexvs.Zvertex of tracks hits/event hits/event ~ 400 ToF hits/event ~ 40 ToF hits/event

  40. Thank you for your attention!

  41. Backup

  42. Comparison of reco background large MuCh ▬ 100μm smearing ▬segmentation + modified tracking

  43. Modified tracking hard tracks soft tracks —μ —π —Κ —p —ghost compact MuCh old tracking hard tracks: ▬ background ▬signals soft tracks ■background ■ signals

  44. MC momentum compact MuCh ▬ ≥ 4 STS + 12 MuCh ▬ ≥ 4 STS + 15 MuCh

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