strategy for physics with cosmic muons
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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Strategy for Physics with Cosmic Muons
• Detector involved
• Trigger
• Events with different trigger
• Topics
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Detection of Atmospheric Muons
Muons are generated in the atmosphere Reach the : SURFACECross the : ROCKArrive in : ALICE
30 meters of rock
SurfaceMuons
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ALICE Detectors for Cosmic Ray Physics
ACORDE
TPC
SPD
TOF
MAGNET
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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)
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SPD Trigger : Typical Event
2 Tracks1 Muon
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SPD Trigger : Typical Events
8 Tracks1 Muon
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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
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• 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
The Track Matching
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SPD Trigger : Muon Multiplicity
2.9 %
0.9 ‰
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SPD Trigger : High Multiplicity
141 tracks
RUN : 60824
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SPD TRIGGER RUN : 60824
707 tracks
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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
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Trigger with TOF
• 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
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Flexibility (example) : Trigger TOF for TRD
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Rate Stability : Trigger TOF for TRD (Side C only)
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Run 37562 Ev 27 ( Trigger: TOF )
TPC hitsTRD hitsTOF hits
Example of real event : Particle interacting in the iron of the magnet
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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
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ACORDE Hit Multiplicity
Mario RodriguezAnalysis Run 62107Magnetic Field ON8.5 hours data
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TPC track multiplicity
RUN 62107
Number of events
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N. TPC tracks vs ACORDE modules
RUN 62107
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ACORDE Trigger
14% of the triggershave at least one track in the TPC
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ACORDE Trigger Multimuons
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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
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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
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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
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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
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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