Baby Pictures of The Universe: Exploring The Nature of Matter at RHIC

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Baby Pictures of The UniverseExploring The
Nature of Matter at RHIC
John Lajoie Iowa State University lajoie_at_iastate.e
du
1. Nuclear Physics and Quantum Chromodynamics 2.
Creating the QGP in Little Bangs at RHIC 4.
Signals for the Quark Gluon Plasma 5. The PHENIX
Experiment
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Quarks, Mesons and Hadrons
Three color charges red, green and blue.
Force mediated by gluons.
Color Singlet States
No Free Quarks!
Proton uud Neutron udd
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Quantum Chromodynamics (QCD)
The potential between two quarks grows linearly
with their separation.
The QCD coupling constant grows as the momentum
transfer decreases.
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QCD Vacuum Structure
Superconductor
QCD Vacuum
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Lattice QCD
Chiral Condensate
Boyd G, et al., Phys. Lett. 349B170 (1995)
Energy Density and Pressure
Blum T, et. al., Phys. Rev. D 515153 (1995)
The vacuum melts at TTC !
The energy density and pressure rise with the
release of color degrees of freedom and chiral
symmetry restoration!
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Phase Diagram of Nuclear Matter
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The Early Universe
Up to 10ms old the Universe was a Quark-Gluon
Plasma!
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Heavy Ion Collisions
The interaction of the two nuclei creates a
region of high energy density (and low net baryon
density) - sparking the vacuum and creating a
Quark-Gluon Plasma!
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QGP Signatures
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Energy Density
following Bjorken ( Phys. Rev. D27, 140 (1983) )
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RHIC _at_ Brookhaven National Laboratory
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The PHENIX Collaboration
445 Collaborators 44 Participating Institutions
in 10 Countries Spokesman Bill Zajc (Columbia
University) Project Director Sam Aronson (BNL)
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The PHENIX Detector
EM Calorimeter
Beam-Beam Counter
Time Expansion Chamber
Muon Tracking Chambers
Central Arms
Muon ID Panels
Pad Chambers
North Muon Arm
Multiplicity/Vertex Detector
Drift Chambers
South Muon Arm
Time of Flight Panels
Ring Imaging Cerenkov
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PHENIX Design Philosophy

• Flexibility to handle new experimental
  environment
• Use wide-ranging capabilities of RHIC accelerator
• Redundant measures to control, understand
  systematics
• Exploit high RHIC luminosity of light colliding
  species
• Designed with long-term physics program in mind
• Systematic body of data needed to find/study QGP
• PHENIX spin program
• Physics program designed for large dynamic
  range
• In terms of physics breadth
• High pT direct g, Drell-Yan, charm - early in
  collision
• Hadronization, flow, HBT - late in collision
  evolution
• In terms of data volume
• HBT needs few mb-1 of integrated luminosity
• Measurement of needs tens of 1000s of same

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semi-leptonic D decays
NA44
single particle distributions
NA50
heavy flavor decay
strangeness production
Nch, dNch/dh, fluctuations
spin program W,W-
WA80
E859
jet quenching
ET, dET/dh, fluctuations
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Physics Goals

• Detect, identify, characterize leptons, hadrons,
  photons
• PHENIX is an integrated set of spectrometers
• Two 1-sr spectrometers in central region
• electrons, electron pairs, photons,
  charged/neutral hadrons
• Two 1-sr muon spectrometers in forward regions
• muons, muon pairs
• Study collisions as function of energy density
• Inferred from dNch/dh, dET/dh via usual Bjorken
  picture
• Excellent momentum resolution, particle
  identification
• High rate, sophisticated triggering
• Rare probes, hard processes

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Physics Goals

• Seeing QGP will require correlation of many
  measurements
• Global event information
• Multiplicity, ET, fluctuations, ltpTgt
• Deconfinement
• Differential suppression of y, J/y with respect
  to
• J/y production relative to Drell-Yan, open charm
  production
• Thermal History, Degrees of Freedom
• Direct g , direct g ee-, mm-
• Chiral symmetry restoration
• Mass, width and branching ratio of f ee-, KK-
• Space-time evolution
• HBT correlation of pp, KK
• Strangeness and Charm
• K, K0, f, J/y, D production

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J/Y Suppression
Already some evidence for J/Y suppression?
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CERN NA50
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F-Meson Spectroscopy
The f is only slightly above threshold for
decay to KK- .
The f is very sensitive to the medium it is born
in (chiral symmetry restoration).
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Thermal Radiation
Expect photon excess from pre-equilibrium
plasma in the range 2 lt pT lt 5 GeV/c.
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Average Transverse Momentum
Entropy jump associated with the release of
additional degrees of freedom.
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Acceptance

• Eleven distinct detector subsystems
• Integration is one of biggest challenges for
  Phenix
• Redundant measurements of observables
• E.g., RICH EMCal TEC (tracking dE/dx) for p
  /e lt 10-4
• PHENIX geometric acceptance
• Nch over full azimuth, h lt 2.5
• Central Arms, 2 x (Df p/2), h lt 0.35

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Charged Particles
MVD Mechanical Prototype

• Multiplicity/Vertex Detector
• Two coaxial barrels, endcaps
• 200 mm wide silicon strips/pads
• 2mm 3D vertex accuracy
• Minimal radiation thickness (1)
• Wide coverage h lt 2.5
• Nch, dNch/dh, fluctuations
• Can detect dNch 10 per 0.2 unit h bin

Single Event dNch/dh in MVD
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Electromagnetic Calorimetry

• Pb- Scintillator and Pb-Glass
• 15K PbSc, 10K PbGl
• Fine energy, time resolution
• High granularity
• 2 primary particle occupancy
• Direct g
• pTgt5 GeV/c - pQCD processes
• 2ltpTlt5 GeV/c - pre-equilibrium
• pTlt2 GeV/c - thermal, mixed-phase
• Production of h, p0
• Jet tagging
• High pT p0 strongly associated with jets
• Useful for triggering
• 10-3 of minimum bias rate

Test beam results
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Central Tracking

• Drift, Pixel Pad, Time Expansion Chambers
• Precise projective tracking
• Space points for pattern recognition
• Excellent mass resolution
• Comparable to f intrinsic width
• dE/dx in TEC also aids particle ID

Mass resolution
dE/dx in TEC
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Time-of-Flight (TOF)
TOF Slats

• Beam-beam Counter
• Quartz Cerenkov telescopes
• 50 ps timing
• Time of flight panels
• 1/2 of one central arm
• Better than 85ps timing resolution
• 4s K-p separation to 2.5 GeV/c
• EMCal timing resolution
• PbSc - s280ps for hadrons

TOF in WA98
Beam-beam Counter
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Electrons

• RICH TEC EMCal gives p /e lt 10-4
• Electron arm acceptance
• Central rapidity, low pT threshold
• ee- mass gt 400-500 MeV
• Light vector mesons
• Possible mass, width shifts
• Enhancement of r by regeneration
• J/y,y measurement
• Charm and the single electron
• Enhanced e in pT 1-5 GeV/c
• Dilepton continuum and charm

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Muon Tracking

• Resolution and p rejection
• 10-4 p/m, 100mm resolution
• Vector mesons
• Differential suppression of y, J/y
• R(y) gt R(J/y) gt R()
• Reference to D-Y or open charm
• Distinguish initial/final state effects
• High pT m from heavy flavor decay

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Physics Strategy
Full PHENIX Program Drell-Yan , mm- vector
mesons ee- open charm spin ...
f KK- single high pT leptons J/y mm-
Nch, dNch/dh, ET, dET/dh pT spectra,
HBT inclusive g, p0
mb-1
Integrated RHIC Luminosity
Year 1
Year 2
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Current Status of PHENIX

• Many ways to quantify progress
• 95 of PHENIX mass installed
• 70 of funds committed
• Heavy metal
• South muon magnet installation at BNL under way
• Other magnets turned on, mapping procedure tested
• Subsystems progressing well
• Mechanical
• In production, ordering production parts, setting
  up factories
• Electronics
• Chips in either production or final prototyping
• Beam-beam, TOF, PbGl essentially ready to install

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Summary

• Detect, identify, characterize leptons, hadrons,
  photons
• Designed for flexible, broad, long-range program
• From Nch to dET/dh to ltpTgt to HBT to g to J/y to
  
• Highly segmented, high resolution calorimetry
• Excellent PID capabilities
• Physics program exploits the very highest RHIC
  luminosity
• PHENIX well on way to completion
• Compelling physics results - from day one onward

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STAR
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BRAHMS
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PHOBOS
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PHENIX Cinema
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Detector Installation
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Level-1 Trigger (ISU)
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Hard Scattering and Jets
Low momentum particles arise from soft (large
distance scale) interactions. High transverse
momentum particles arise from parton (quark and
gluon) scattering.
How does a QGP affect the evolution of jets?
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Jets and the QGP
Energy loss and rescattering in the QGP
dE/dz reduced or increased in the plasma?
Energy imbalance in back-to-back jets? Jet
acoplanarity?
q
Jet Flavor Tagging Select quark-quark and
quark-gluon jets (average gluon carries
smaller momentum fraction) High-pT
particles reflect scattered partons.
q
g
q