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Strategy for Physics with Cosmic Muons

Strategy for Physics with Cosmic Muons. Detector involved Trigger Events with different trigger Topics. 30 meters of rock. Detection of Atmospheric Muons. Muons. Surface. Muons are generated in the atmosphere Reach the : SURFACE Cross the : ROCK Arrive in : ALICE.

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Strategy for Physics with Cosmic Muons

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  1. Strategy for Physics with Cosmic Muons • Detector involved • Trigger • Events with different trigger • Topics

  2. 30 meters of rock Detection of Atmospheric Muons Muons Surface Muons are generated in the atmosphere Reach the : SURFACE Cross the : ROCK Arrive in : ALICE

  3. ALICE Detectors for Cosmic Ray Physics ACORDE TOF MAGNET SPD TPC

  4. TRIGGER • SPD  atm. muons low multiplicity mu interaction in magnet iron (0.1 Hz) • TOF  atmospheric muons mu intercation in magnet iron (very flexible) • ACORDE  atmospheric muons (100 Hz)

  5. SPD Trigger : Typical Event • Tracks • 1 Muon

  6. SPD Trigger : Typical Events • Tracks • 1 Muon

  7. The Analysis Cuts • Select tracks with > 20 clusters in TPC • Loop on tracks and : 1 track && TPC cls > 70 → 1 μ • 2 tracks: • if (θ and φ match) || (either track has TPC cls > 70) → 1 μ • 3 to 6 tracks: • count matching tracks (see next slide) • > 6 tracks: save event, visual scan

  8. The Track Matching • θ and φ matching means • θ1 + θ2 = π ± 0.1 • | φ1 - φ2 | = π ± 0.2 • tracker make tracks start from central region and go opposite • for 3 to 6 tracks • loop on tracks, search for a couple inside ITS • match θ and φ as above • spatial matching: | Xv1 -Xv2 | < 1.0 && | Yv1 - Yv2 | < 1.0 && | Zv1 - Zv2 | < 20.0 • if match: Nμ++ , take them away from the list, save θ and φ • loop on remaining tracks • if two match and have same θ, φ as ITS track: Nμ++ and take them out • if a track doesn't match with any other but has θ,φ : if outside ITS (| Xv | > XITS && | Zv | > ZITS) Nμ++ and take it away from the list

  9. 2.9 % 0.9 ‰ SPD Trigger : Muon Multiplicity

  10. SPD Trigger : High Multiplicity RUN : 60824 141 tracks

  11. SPD TRIGGER RUN : 60824 707 tracks

  12. Cosmic events with SPD trigger • Analysis of high multiplicity events • Run : • 60281 8h 6m 9 events > 6 tracks • 60305 2h 02m 3 events > 6 tracks • 60824 8h 12m 210 events > 6 tracks and 20 events > 20 tracks SPD trigger  7-8 events per minute We can estimate 1-2 events per hour with high multiplicity  Probably muon intercation in iron

  13. TOF works well in ALICE  low background 0.2 Hz/cm2 Good stability Very flexible Allow to decide the trigger topology (vertical muons for example) and the rate Trigger with TOF

  14. Flexibility (example) : Trigger TOF for TRD

  15. Rate Stability : Trigger TOF for TRD (Side C only)

  16. TPC hits TRD hits TOF hits Example of real event : Particle interacting in the iron of the magnet Run 37562 Ev 27 ( Trigger: TOF )

  17. Trigger with ACORDE 60 modules on the three upper octants of the L3 magnet : Each module = 20 cm x 190 cm Area 1 scintillator = 0.38 m2 Total Area = 23 m2

  18. ACORDE Hit Multiplicity Mario Rodriguez Analysis Run 62107 Magnetic Field ON 8.5 hours data

  19. TPC track multiplicity Number of events RUN 62107

  20. N. TPC tracks vs ACORDE modules RUN 62107

  21. ACORDE Trigger 14% of the triggers have at least one track in the TPC

  22. ACORDE Trigger  Multimuons

  23. High multiplicity in ACORDE File:/Volumes/MRC/RunsAliEn/Run62107/08000062107000.140/AliESDs.root, N. of Event:2402, ACORDE Multiplicity:7, No. of ESD's tracks:1

  24. High multiplicity in ACORDE File:/Volumes/MRC/RunsAliEn/Run62107/08000062107000.30/AliESDs.root, N. of Event:14692, ACORDE Multiplicity:5, No. of ESD's tracks:1

  25. High multiplicity in ACORDE and TPC File:/Volumes/MRC/RunsAliEn/Run62107/08000062107000.460/AliESDs.root, N. of Event:8560, ACORDE Multiplicity:35, No. of ESD's tracks:148

  26. Cosmic Ray Physics with ALICE • Trigger SPD : High Multiplicity Events • 200 hours of data taking with B=ON • Study mu interaction in iron • Trigger TOF : Topology and Rate Flexible • Atmospheric muons and mu int. in iron • Trigger ACORDE : • Atmospheric muons • At least 30 days of data taking better with B=ON

  27. Physics Topics • Atmospheric muons • Multi-muon Distribution • Correlations between Muon Multiplicity and Muon Energy • Measurements on Single Muon (Momentum Distribution, Ratio mu+/mu-) • Event coincidence with other LHC experiment • Muon interaction in iron (muon photonuclear) • Rate of such process • Hadron identifications and energy distributions

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