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Muon identification with realistic detector layout

This presentation outlines the results of muon identification using a realistic detector layout at the 10th CBM Collaboration Meeting. The study includes realistic segmentation of the Muon Chamber (MuCh), invariant mass spectra for low-mass vector mesons and charmonium, time-of-flight measurements, and the identification of J/ψ and Ψ' at 35 AGeV. The results show promising potential for muon identification and good background suppression using time measurements.

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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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