Andrew Glenn ( University of Tennessee ) For the PHENIX Collaboration Fall DNP Meeting Tucson, AZ
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Andrew Glenn(University of Tennessee)
For the PHENIX CollaborationFall DNP Meeting Tucson, AZ
October 31, 2003
Single Muon Production in . = 200 GeV Au+Au
Collisions at thePHENIX Experiment
NNs
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Andrew Glenn, University of Tennessee, 2003
The ApparatusDetector (Iarocci Tubes)
Steel Absorber
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Andrew Glenn, University of Tennessee, 2003
Sources of Muon CandidatesD (B) meson semi-leptonic decays(D K …) Prompt Signal
Decay muons from hadron decays (±± , K±± )
‘Hadron’ Punch Through(±, K±, p)
Decays from J/, , Drell-Yan…(Small Contribution)
PH
MuID
Bac
kgro
un
d
Gap 0 1 2 3 4
Steel absorber
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Andrew Glenn, University of Tennessee, 2003
Data SampleRHIC Run II Au+Au (The first muon capable run)Start With 7.7M Minimum-Bias Events(Cleanest section of running period)
Cuts on:Vertex (-20 to 38cm)
Track Quality (2/DOF < 7, NTrHits >=12)
(-1.51 to -1.79 or = 155 -161o) Uniform acceptance in event vertex.
Azimuthal Cut
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Andrew Glenn, University of Tennessee, 2003
Muon Identification
Sharp Muon Peak
Long tail from interacting hadrons(more evidence to come)
Main muon identification is from momentum/depth matchingPH
3 GeV
1 GeV
3 GeV
MuID
Gap (Plain) 0 1 2 3 4
ste
el
Last Gap = 2
Centrality > 20%
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Andrew Glenn, University of Tennessee, 2003
Peripheral Data Vs Simulation
Simulation: Muons From Central Hijing Data: Centrality > 60 (For cleaner events)
Falsely extended tracksLast Gap = 2
Last Gap = 3
Last Gap = 4
No clear peak or tailsince last gap.
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Andrew Glenn, University of Tennessee, 2003
We want to separate the contribution from prompt muon production and /K decays
Collision Point
nosecone
magnet
Muon trackerMuon ID
40 cm
• D c = 0.03 cm Decays before absorber• c = 780 cm Most are absorbed, but some decay first • K c = 371 cm Most are absorbed, but some decay firstγcτ >> 80cm → Decay Probability nearly constant between nosecones
Collisions occurring closer to the absorber will have fewer decay contributions. Should see a linear increase in decay background with increasing vertex.
Decay Contribution
X
Z
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Andrew Glenn, University of Tennessee, 2003
Vertex Dependence
=Centrality > 20%
Very Linear Shape Due to Decays
Not due to vertex detector resolution Centrality > 20%
Centrality > 20%
1 < pT > 3 GeV/c
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Andrew Glenn, University of Tennessee, 2003
Interacting Hadron Vertex
Interacting Hadrons: Last Gaps 2 and 3, Pz St3 tail. Flat shape indicates little to no decay (hence muon) component
Last Gap = 2
Centrality > 20%
Centrality > 20%
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Andrew Glenn, University of Tennessee, 2003
From simple (event vertex corrected) subtraction of near muons from far muons
(Hence NOT NORMALIZED, also NOT ACCEPTANCE/EFFICIENCY CORRECTED)
Decay pT Distribution
Centrality > 20%
Region II – Region I
Z vertex
Muon Vertex
Region I Region II
Decays
prompt decay + punchthrough??
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Andrew Glenn, University of Tennessee, 2003
SimulationsA first approach to estimate the fraction of decay contribution used HIJING+GEANT Au+Au simulations.
Large statistical error and large error due to lack of HIJING tuning (K/ Ratios, pT distribtions etc.)
With the recent availability of BRAHMS and K data at Muon Arm rapidities, we can examine a data driven simulation approach.
An accurate modeling of K and (and p) production for simulation input is needed for punchthrough estimations.
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Andrew Glenn, University of Tennessee, 2003
Data Driven Particle Generator
Use scaled PHENIX central arm data to for basis of event generator. BRAHMS preliminary data helps with scaling and justification ( P(y,pT) ≈ P(y)P(pT) ). Only measurements for 5% most central events are available from BRAHMS.
5% Most Central Events
BRAHMS data extractedfrom Djamel Ouerdane’s thesis
BRAHMS5% most central
Provides scaling
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Andrew Glenn, University of Tennessee, 2003
Generator First LookSingle K’s and ’s thrown with BRAHMS (preliminary, 5% most central) pT and dN/dy shapes. pT > 1 GeV required. Passed through full simulation/reconstruction.
Decays: 900K Single Hadrons Gives:
Punchthrough: 800K Single Hadrons Gives:
Last Gap Reached Reconstructed Decay Muons
2 161
3 297
4 712
Last Gap Reached Reconstructed Punch Through
2 222
3 150
4 66
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Andrew Glenn, University of Tennessee, 2003
Summary
A significant number of muons were measured in Run II Au+Au.
A fraction of interacing hadrons can be clearly identified. (Helps understand punchthrough)
Muon candidate vertex dependence provides important information about decay contribution.
A simulation procedure is being developed which should allow good estimation of decay and punchthrough contributions.
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Andrew Glenn, University of Tennessee, 2003
Backup Slide
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Andrew Glenn, University of Tennessee, 2003
Simulated Decay MuonsCentral HIJING events ran through GEANT simulation.Closest cuts possible to match data (without full reconstruction).17100 total events distributed over Z=±10, ±20, ±38
Projected contribution of decay muons ends at ~75 cm
Not in fit, Geometric effect also seen in data
Large statistical errorand large error due to lack of HIJING tuning(K/ Ratios etc.)
A better method is needed for both decay and punchthrough estimation.