John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009 Physics in ALICE at the LHC.
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Transcript of John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009 Physics in ALICE at the LHC.
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Physics in ALICE at the LHC
ALICE at the LHC
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
LHC
Alice
Dedicated “general purpose”Heavy Ion experiment at LHC
The ALICE Experiment
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
ALICE Detectors & Acceptance
(charged particles)
µ arm
central barrel -0.9 < < 0.9• = 2 tracking, PID (TPC/ITS/ToF)• single arm RICH (HMPID)• single arm e.m. cal (PHOS)• jet calorimeter (EMCal)
forward muon arm 2.4 < < 4• absorber, 3 T-m dipole magnet10 tracking + 4 trigger chambers
multiplicity detectors -5.4 < < 3• including photon counting in PMD
trigger & timing detectors• 6 Zero Degree Calorimeters• T0: ring of quartz window PMT's• V0: ring of scint. Paddles
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
The ALICE Experiment (Installation)
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
ALICE Detectors in 2009 at LHC
• Complete – fully installed & commissioned
– ITS, TPC, TOF, HMPID, MUONS, PMD, V0, T0, FMD, ZDC, ACORDE,
TRIGGER, DAQ
• Partially completed
– TRD (20%) completed now
– PHOS (20%) completed now
– EMCAL (20%) just completed, installation in current shutdown
• At start-up full hadron and muon capabilities
• Partial electron and photon capabilities
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
04/18/23
The TPC Performance
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
~6.5% resolution in central Pb+Pb
2 2 2 222max
2 20
21 ( )2 ln
2 2 2e em c m c EE Zz
Cx A I
Energy loss (dE/dx)
separation power
to 50 GeV
PID
Tracking(cosmic rays)
First LHC Beam in ALICE
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
• ALICE ready for LHC collisions.
• First LHC proton beams circulated on
September 10th , 2008.
• 450 GeV/c proton + pixel interaction
Early p + p Physics in ALICE
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
• “Day 1” physics with p + p: global event properties (energies - 0.9/10/14 TeV?)
• requires only several x 10K events
< pT > vs Nch
Multiplicity distributions
< dNch /d|= 0 >
ALICE Heavy Ion Physics
Overview:
Soft Probes – “same as RHIC and Beyond” • Expansion dynamics different from RHIC• Soft physics measurements similar to RHIC
+ extended PID• Day 1 physics +
Hard Probes – Heavy Quarks• Displaced vertices (Do K- +) from TPC/ITS• Electrons in Transition Radiation Detector (TRD)
Hard Probes – Quarkonia• J/, , ’ (excellent), ’’(2-3 yrs), ’ ???
Hard Probes – Jet Quenching• Jets, pi-zeros, leading particles to large pT
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Soft Physics in ALICELHC Heavy Ions –
• expectations based on QCD predictions, p + p extrapolations, & RHIC results• a lesson from RHIC “expect the unexpected” versatility!! ALICE!!
Soft Physics (pT ≤ 2 GeV/c) with heavy ions at LHC – • Is there a smooth extrapolation from SPS RHIC LHC?
ALICE
Particle Multiplicities
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
dNch/dy = 2600
dNch/dy = 1200
ln(√s) extrapolation
saturation model
Eskola hep-ph/050649
J. Phys. G 30 (2004) 1540
Soft Physics in ALICELHC Heavy Ions –
• expectations based on QCD predictions, p + p extrapolations, & RHIC results• a lesson from RHIC “expect the unexpected” versatility!! ALICE!!
Soft Physics (pT ≤ 2 GeV/c) with heavy ions at LHC – • smooth extrapolation from SPS RHIC LHC?• expansion will be different (HBT, v2, Tchem & Tkin,
strange/charm particles & resonances)
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Hirano et al, nucl-th/0701075v2
N.Borghini & U.A.Weidemann, J.Phy.G 35 (2008) 023001
Equilibrium / Non-Equilibrium in ALICE
Non-equilibriums (s = 3 - 5)oversaturated
Equilibrium s = 1
Many additional questions: Strangeness enhancement? Correlation volume? Evolution in pp & PbPb?
B. Hippolyte et al.EPJ C49 (2007)
at LHC expect : Tch = 161 ± 4 MeVB = 0.8+1.2-0.6 MeV
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Andronic et al.nucl-th/0511071
Rafelskiet al.E. J. Phys.C45 (2006) 61
Resonances (, , K*, …) Hadrons
• Reconst invariant mass spectrum, background subtract (like-sign method). • Mass resolutions ~ 1.5 - 3 MeV . pT statistical limits: 8 () to 15 GeV/c (,K*)
K*(892)0 K 15000 central Pb-Pb
K+K-
Mass resolution ~ 1.2 MeV
central Pb-Pb
Mass resolution ~ 2-3 MeV
Invariant mass (GeV/c2)
Short-lived resonances:
Invariant mass (GeV/c2)
Invariant mass (GeV/c2)
• Time difference between chemical and kinetic freeze-out • In medium modifications of mass, width, comparison of hadronic and leptonic channels → partial chiral symmetry restoration?
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Resonances (, , , J/) e+e-
Short-lived resonances:
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
2 x 107 Pb+Pb events
• In medium modifications of mass, width, comparison of hadronic and leptonic channels → partial chiral symmetry restoration?
2 x 107 Pb+Pb events
Short-lived resonances:• In medium modifications of mass, width, comparison of hadronic and leptonic channels → partial chiral symmetry restoration?
2 x 107 Pb+Pb events - : significance = 12 - 15J/: significance = 40 - 50
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Resonances (, , , J/) e+e-
Hard Probe Rates in ALICE
ALICE hard physics capabilities:- Electron/hadron disc. (TRD, EMCal)
- measurements (forward muon arm)
- Good discrimination (EMCal, PHOS)
- Fast trigger on jets (EMCal)
Hard Probes statistics in ALICE:
104/year in minbias Pb+Pb:
inclusive jets: ET ~ 200 GeV
dijets: ET ~ 170 GeV
: pT ~ 75 GeV
inclusive : pT ~ 45 GeV
inclusive e: pT ~ 30 GeVThanks – Peter Jacobs
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Hard Probes in ALICE – Heavy Quarks
Heavy Quarks (mass/color dep. of parton E-loss)
• Displaced vertices (Do K- +) from TPC/ITS• Electrons in Transition Radiation Detector (TRD)
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Heavy Quark RAA at RHIC & LHC!
Uncertainties at RHIC (bands > ±0.1 ) - perturbative production of c and b jets - ratio of c to b jets is very uncertain.
Wicks & Gyulassy, Last Call for LHC Predictions
RHIC LHC
Heavy quark electrons at RHIC D & B mesons at LHC
LHC: - Different slopes of spectra
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Charm & Beauty E-Loss Ratios in ALICEDisplaced vertices (Do K- +) from trackingElectrons from Transition Radiation Detectors1 nominal year: 107 central Pb-Pb events, 109 pp events
errors: statistical (bars) and systematic (bands)
Sensitive to color charge
Sensitive to mass dep.E-loss calc.: Armesto, Dainese, Salgado, Wiedemann
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Charm and Beauty E-Loss : RAA
D0 K
1 year at nominal luminosity(107 central Pb-Pb events, 109 pp events))
B e + X
D+ K
mC = 1.2 GeV
mC = 0
mb = 4.8 GeV
B eE-loss calc: Armesto, Dainese, Salgado, Wiedemann
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Hard Probes in ALICE – QuarkoniaHeavy Quarks (mass/color dep. of parton E-loss)
• Displaced vertices (Do K- +) from TPC/ITS• Electrons in Transition Radiation Detector (TRD)
Quarkonia (Initial T, Debye screening, recombination,..)
• J/, , ’ (excellent), ’’(2-3 yrs), ’ (very difficult)
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Quarkonia
John Harris (Yale U.) US LHC User’s Meeting, 24 October 2008
T/TC 1/r [fm-1]
(1S)
J/(1S)
c(1P)
’(2S)
b’(2P)
’’(3S)
Karsch hep-lat/0502014v2
Measure melting order of cc: ’, c, J/bb: ’’, ’,
Heavy Quarks (mass/color dep. of parton E-loss)
• Displaced vertices (Do K- +) from TPC/ITS• Electrons in Transition Radiation Detector (TRD)
Quarkonia (Initial T, Debye screening, recombination,..)
• J/, , ’ (excellent), ’’(2-3 yrs), ’ (very difficult)
04/18/23
Particle Charmonia +- Charmonia e+e- Bottomonia +- Bottomonia e+e-
mass plots
(- bkg)
accept. -4 < < -2.5 || < 0.9 -4 < < -2.5 || < 0.9
M 65 MeV 35 MeV 90 MeV 90 MeV
S / (S+B) J/ 150, ’ 7 J/ 245
30, ’ 12,
’’ 8 21, ’ 8
channel , ’ , ’ , ’,’’ , ’, no ’’pt J/ 0-20 GeV J/ 0-10 GeV 0-8 GeV --
Quarkonia PerformancedNch/dy = 4000 in central Pb-Pb for 1 month
Hard Probes in ALICE – Jet Quenching
Heavy Quarks (mass/color dep. of parton E-loss)
• Displaced vertices (Do K- +) from TPC/ITS• Electrons in Transition Radiation Detector (TRD)
Quarkonia (Initial T, Debye screening, recombination,..)
• J/, , ’ (excellent), ’’(2-3 yrs), ’ (very difficult)
Jet Quenching (in next talk by Rene Bellwied) (E-loss, parton density, fragmentation, medium response)
• Jets, pi-zeros, leading particles to large pT
• Modification of fragmentation• Medium response to E deposition - dissipation on near- and away-side
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009
Summary & Questions to AddressALICE – is a versatile, general purpose heavy ion detector at LHC
will contribute significantly to understanding of (soft & hard) HI physics
ALICE to address general (Soft Physics) Questions:How does the system evolve and thermalize from its initial state?What are the properties of the quark-gluon plasma at LHC energies?Is QCD Phase Diagram featureless above Tc? Coupling strength vs T….?Are there new phenomena?
ALICE to address Physics Questions with Hard Probes:What is the behavior of c-cbar and b-bar states in-medium?
(Ti, screening/suppression, enhancement?)Can we understand parton energy loss at a fundamental level?
Medium modifications? e.g. jet energies in ALICE up to ~ 225 GeV possible (stats) B-jets up to 80 – 90 GeV (stats in one PbPb month)Flavor dependence? (D, B, quark- and gluon-jets?)
Can we understand the hadronization (fragmentation) process?
Theory?Range of validity of theories (hydro, non-pQCD, pQCD, strings…)?Can there be new developments in theory, and understanding across fields? (lattice, hydro, string, pQCD E-loss,…)
End
John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009