Polarized beam in RHIC in Run 2011. Polarimetry at RHIC A.Zelenski, BNL
Beam Energy Scan Program at RHIC
description
Transcript of Beam Energy Scan Program at RHIC
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Beam Energy Scan Program at RHIC Michal Šumbera
Nuclear Physics Institute AS CR, Řež/Prague
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World’s (second) largest operational heavy-ion colliderWorld’s largest polarized proton collider
RHIC BRAHMSPHOBOSPHENIX
STAR
AGS
TANDEMS
Relativistic Heavy Ion ColliderBrookhaven National Laboratory (BNL), Upton, NY
Animation M. Lisa
Year System sNN [GeV]
2000 Au+Au 130
2001 Au+Au 200
2002 p+p 200
2003 d+Au 200
2004 Au+Aup+p
200, 62.4200
2005 Cu+Cu 200, 62.4, 22
2006 p+p 62.4, 200, 500
2007 Au+Au 200
2008d+Aup+p
Au+Au
2002009.2
2009 p+p 200, 500
2010 Au+Au 200, 62.4, 39, 11.5, 7.7
2011 Au+Aup+p
200,19.6,27500
2012 U+UCu+Au
p+p
193200
200,510
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Recorded Datasets
Fast DAQ + Electron Based Ion Source + 3D Stochastic cooling
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– Perfect liquid BRAHMS, PHENIX, PHOBOS, STAR, Nuclear Physics A757 (2005)1-283
– Number of constituent quark scaling PHENIX, PRL 91(2003)072301; STAR, PR C70(2005) 014904
– Jet quenching PHENIX, PRL 88(2002)022301; STAR, PRL 90(2003) 082302
– Heavy-quark suppression PHENIX, PRL 98(2007)172301, STAR, PRL 98(2007)192301
– Production of exotic systems• Discovery on anti-strange nucleus STAR, Science 328 (2010) 58
• Observation of anti-4He nucleus STAR, Nature 473 (2011) 353
– Indications of gluon saturation at small x STAR, PRL 90(2003) 082302; BRAHMS, PRL 91(2003) 072305; PHENIX ibid 072303
Remarkable discoveries at RHIC
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Introducing sQGP …
1st/2nd order
QCD Phase Diagram
Crossover
Particle Physics
~21012K
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… and how was it discovered
<Nbinary>/sinelp+p
Nucleus-nucleus yield
AA hadronsleadingparticle suppressed
q
q
?
NULL Result
If R = 1 here, nothing “new” is going on
Scaling AA to pp (or central to peripheral)
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FERMILAB-Pub-82/59-
THY
Phys.Lett.B243(1990)432
Au + Au Experiment d + Au Control Experiment
• Dramatically different and opposite centrality evolution of Au+Au experiment from d+Au control experiment.
New state of matter is produced in central Au+Au collisions at √sNN=200GeV
Suppresion of leading hadrons at RHIC
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…and at LHC …
ALICE, Phys.Lett. B696 (2011)30
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Single hadron RAA: RHIC vs LHC
RAA
RAA for both systems looks similar
LHC: Suppression of inclusive jets
13Like for charged particles, high-pT jet RAA flat at ≈ 0.5
Fully unfolded inclusive jet RAA pp 2.76 TeV reference
CMS-PAS HIN-12-004
Dihadron azimuthal correlations at RHIC
Azimuthal distribution of hadrons with pT > 2 GeV/c relative to trigger hadron with pT
trig > 4 GeV/c (background subtracted). Data are from p+p, central d+Au and central Au+Au collisions.
STAR, PRL 90(2003) 082302
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Photon tag:• Identifies jet as u,d quark jet• Provides initial quark direction• Provides initial quark pT
Jet (98 GeV)
Photon(191GeV)
… and g+jet at LHC
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Energy Dependence of Elliptic Flow
ALICE: PRL 105 (2010) 252302
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v2(pT): LHC vs. RHIC
The same flow properties from √sNN=200 GeV to 2.76 TeV
ALICE: PRL 105 (2010) 252302
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1) QuenchingAll hard hadronic process are strongly quenched 2) FlowPanta rhei: All soft particles emerge from the common flow field
The ‘Standard Model’ of high energy heavy ion collisions
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0) Turn-off of sQGP signatures
1) Search for the signals of phase boundary 2) Search for the QCD critical point
Why to go to lower energies?
QGP Turn-offCritical Point
First
Order
First Order
Phase Transition
Cross-Over
The RHIC Beam Energy Scan Project• Since the original design of RHIC (1985), running at lower energies has been envisioned.
• Possibilities of RHIC running at lower energies were studied with a series of test runs: 19.6 GeV Au+Au in 2001, 22.4 GeV Cu+Cu in 2005, and 9.2 GeV Au+Au in 2008.
• In 2009 the RHIC PAC approved a proposal to run a series of six energies to search for the critical point and the onset of deconfinement.
• These energies were run during the 2010 and 2011 running periods.
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Selected Results
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(0-5
%/6
0-80
%)
STAR Preliminary
Suppression of Charged Hadrons …
PRL 91, 172302 (2003)
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(0-5
%/6
0-80
%)
STAR Preliminary
… and its Disappearance
RCP ≥ 1 at √sNN ≤ 27 GeV - Cronin effect?
PRL 91, 172302 (2003)
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STAR Preliminary
RCP : Identified Particles
RCP (K0s) < 1 @ √sNN > 19.6 GeV
RCP > 1 @ √sNN ≤ 11.5 GeV For pT > 2 GeV/c:
• Baryon-meson splitting reduces and disappears with decreasing energy
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W/f ratio falls off at 11.5 GeV
STAR Preliminary
Baryon/Meson Ratio
v1(y) is sensitive to baryon transport, space - momentum correlations and QGP formation
Azimuthal Anisothropy
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1 2 cos ( )n nn
dN v nd
Generated already during the nuclear passage time
(2R/g≈.1 fm/c@200GeV)
⇒ It probes the onset of bulk collective dynamics during thermalization
Directed flow is quantified by the first harmonic:
rapidity
<px> or directed flow
Directed flow is due to the sideward motion of the particles within the reaction plane.
(preequilibrium)26
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STAR Preliminary
v 1Directed Flow of p and π
Mid-central collisions:Pion v1 slope: Always negative (7.7-39 GeV)(Net)-proton v1 slope: changes sign between 7.7 and 11.5 GeV - may be due to the contribution from the transported protons coming to midrapidity at the lower beam energies
p π
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Energy Dependence of v2
• The rate of increase with collision energy is slower from 7.7 to 39 GeV compared to that between 3 to 7.7 GeV
ALICE: PRL 105, 252302 (2010)PHENIX: PRL 98, 162301 (2007) PHOBOS: PRL 98, 242302 (2007) CERES: Nucl. Phys. A 698, 253c (2002).E877: Nucl. Phys. A 638, 3c(1998). E895: PRL 83, 1295 (1999). STAR 130 Gev:
Phys.Rev. C66,034904 (2002).STAR 200 GeV:
Phys.Rev. C72,014904 (2005).
STAR Preliminary
STAR, ALICE: v2{4} resultsCentrality: 20-30%
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v2(pT): First Result
STAR: Nucl.Phys. A862-863(2011)125
v2 (7.7 GeV) < v2 (11.5 GeV) < v2 (39 GeV) v2 (39 GeV) ≈ v2 (62.4 GeV) ≈ v2 (200 GeV) ≈ v2 (2.76 TeV)
⇒ sQGP from 39 GeV to 2.76 TeV
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v2(pT): Final ResultSTAR Coll.: e-Print arXiv:1206.5528
For pT < 2 GeV/c: v2 values rise with increasing √sNN For pT ≥ 2 GeV/c: v2 values are (within stat. errors) comparableThe increase of v2 with √sNN,could be due to change of chemical composition and/or larger collectivity at higher collision energy.
ALICE data: PRL 105, 252302 (2010)
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Corresponding anti-particlesParticles
v2 vs. mT-m0
Baryon–meson splitting is observed when collisions energy ≥ 19.6 GeV for both particles and the corresponding anti-particles For anti-particles the splitting is almost gone within errors at 11.5 GeV
STAR Preliminary
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Particles vs. Anti-particles Beam energy ≥ 39 GeV• Δv2 for baryon and anti-baryon within 10%• Almost no difference for mesons Beam energy < 39 GeV• The difference of baryon and
anti-baryon v2
→ Increasing with decrease of beam energy
At √sNN = 7.7 - 19.6 GeV • v2(K+)>v2(K-) • v2(π-) >v2(π+) Possible explanation(s)• Baryon transport to midrapidity?
ref: J. Dunlop et al., PRC 84, 044914 (2011)• Hadronic potential? ref: J. Xu et al., PRC 85, 041901 (2012)
The difference between particles and anti-particles is observed
STAR Preliminary
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Universal trend for most of particles – ncq scaling not broken at low energies ϕ meson v2 deviates from other particles in Au+Au@(11.5 & 7.7) GeV: ~ 2σ at the highest pT data point
Reduction of v2 for ϕ meson and absence of ncq scaling during the evolution the system remains in the hadronic phase [B. Mohanty and N. Xu: J. Phys. G 36, 064022(2009)]
NCQ Scaling Test
Particles STAR Preliminary
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Accessing Phase Diagram
T-mB:From spectra and ratios
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p, K, p Spectra
STAR Preliminary
Slopes: p > K > p. Proton spectra: without feed-down correctionp,K,p yields within measured pT ranges: 70-80% of total yields
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STAR PreliminarySTAR Preliminary
Strange Hadron SpectraX
Au+Au 39 GeVAu+Au 39 GeV
K0s L
Au+Au 39 GeV
f, K0s: Levy function fit
L, X : Boltzmann fit L: feed-down corrected
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STAR Preliminary
Chemical Freeze-out Parameters
Centrality dependence of freeze-out temperature with baryon chemical potential observed for first time at lower energies
THERMUS* Model:Tch and mB
Particles used: p, K, p, L, K0
s, X
S. Wheaton & J.Cleymans, Comp. Phys. Com. 180: 84, 2009.
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STAR Preliminary
Au+Au
Kinetic Freeze-out Parameters
Higher kinetic temperature corresponds to lower value of average flow velocity and vice-versa
Blast Wave: Tkin and <b>
Particles used: p,K,p
STAR Preliminary
1. Turn-off of QGP signatures:• NCQ breaks down below 19.6 GeV• High pt suppression not seen below 19.6 GeV• LPV effect not seen below 11.5 GeV
2. Evidence of the first order phase transition.• v1 sign change above 7.7• Inflection in v2 and dET/dh at 7.7 • Azimuthal HBT signal inconclusive
3. Search for the critical point. • K/p, K/p, or p/p fluctuations are not conclusive.• Higher moments of the proton distributions
Overview of the BES I Results
Clear
Evidence
StrongHints
Hints
Daniel Cebra @ APS DNP Meeting – Town MeetingNewport Beach, CA, 10/26/2012
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Beam Energy Scan Phase- II
Beam Energy Scan II
BES II
•BES II will focus on the most interesting regions of the phase diagram
•Electron cooling is key to the feasibility of this program; without cooling, BES II would take ~70 weeks
√SNN (GeV) 62.4 39 27 19.6 15 11.5 7.7
mB (GeV) 70 115 155 205 250 315 420
BES I (MEvts) 67 130 70 36 --- 11.7 4.3
Rate(MEvts/day) 20 20 9 3.6 1.6 1.1 0.5
BES II (MEvts) --- --- --- 400 100 120 80
eCooling factor --- --- --- 8 6 4.5 3
Beam (weeks) --- --- --- 2.0 1.5 3.5 7.5
Add a week between each energy, and BES II program will take about 17 weeks
Daniel Cebra @ APS DNP Meeting – Town MeetingNewport Beach, CA, 10/26/2012
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A. Fedotov, W. Fischer, private discussions, 2012.
BES Phase-II proposal Electron cooling will provide increased luminosity ~ 10 times Proposal BES-II (Years 2015-2017):
√sNN [GeV] μB [MeV] Requested (Collected) Events(106)
Au+Au 19.6 206 400 (36)
Au+Au 15 256 100 (0)
Au+Au 11.5 316 120 (11.7)
Au+Au 7.7 420 80 (4.3)
U+U: ~20 ~200 100
At current rates, this would take ~70 weeks of RHIC operations!Isn’t there a better way? Yes! We can cool the beams!
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1% Au target
A. Fedotov, W. Fischer, private discussions, 2012.
BES Phase-II proposal Electron cooling will provide increased luminosity ~ 10 times Proposal BES-II (Years 2015-2017):
√sNN [GeV] μB [MeV] Requested (Collected) Events(106)
Au+Au 19.6 206 400 (36)
Au+Au 15 256 100 (0)
Au+Au 11.5 316 120 (11.7)
Au+Au 7.7 420 80 (4.3)
U+U: ~20 ~200 100
- Annular 1% gold target inside the STAR beam pipe - 2m away from the center of STAR- Data taking concurrently with collider mode at beginning of each fill
No disturbance to normal RHIC running
Fixed Target Proposal:
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Fixed Target Set-up
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BES Program Summary
206 5851120 420
2.557.719.639
775
√sNN (GeV)
mB (MeV)
QGP
pro
perti
es
BES
phas
e-I
Test
Run
Fixe
d Ta
rget
BES
phas
e-II
Large range of mB in the phase diagram !!!
Explore QCD Diagram
Timeline for RHIC’s Next DecadeYears Beam Species and Energies Science Goals New Systems Commissioned
2013 • 500 GeV • 15 GeV Au+Au
• Sea antiquark and gluon polarization • QCD critical point search
• Electron lenses • upgraded pol’d source • STAR HFT
2014 • 200 GeV Au+Au and baseline data via 200 GeV p+p (needed for new det. subsystems)
• Heavy flavor flow, energy loss, thermalization, etc.
• quarkonium studies
• 56 MHz SRF • full HFT• STAR Muon Telescope
Detector • PHENIX Muon Piston
Calorimeter Extension (MPC-EX)
2015-2017
• High stat. Au+Au at 200 and ~40 GeV
• U+U/Cu+Au at 1-2 energies
• 200 GeV p+A • 500 GeV
• Extract h/s(Tmin) + constrain initial quantum fluctuations
• further heavy flavor studies • sphaleron tests @ mB0• gluon densities & saturation • finish p+p W prod’n
• Coherent Electron Cooling (CeC) test
• Low-energy electron cooling
• STAR inner TPC pad row upgrade
2018-2021
• 5-20 GeV Au+Au (E scan phase 2)
• long 200 GeV + 1-2 lower s Au+Au w/ upgraded dets.
• baseline data @ 200 GeV and lower s
• 500 GeV • 200 GeV
• x10 sens. increase to QCD critical point and deconfinement onset
• jet, di-jet, g-jet quenching probes of E-loss mechanism
• color screening for different qq states
• transverse spin asyms. Drell-Yan & gluon saturation
• sPHENIX • forward physics upgrades
Steve VigdorDNP Town Meeting
Oct. 25, 2012
Is there another way?
Can another facility do this faster? Or better?
The Alternatives
•Time Line: 2009-2015•Energy Range: √sNN=4.9 - 17.3 GeV •mB = 0.560 - 0.230 GeV
BES I
Runn
+ Running now, that’s good+ Energy range is good- But fixed-target- And light ions Not Ideal
Super Proton Synchrotron (SPS)
Daniel Cebra @ APS DNP Meeting – Town MeetingNewport Beach, CA, 10/26/2012
Nuclotron based Ion Collider fAcility (NICA)•Time Line: Not yet funded. Plan is to submit documents by end of 2012.
Operations could not begin before 2017 (probably much later)•Energy Range: √sNN = 3.9 - 11 GeV for Au+Au; mB = 0.630 - 0.325 GeV.
Multi-Purpose Detector (MPD)
+ Collider, that’good+ High Luminosity expected• MPD simiar to STAR• Maybe as early as 2017- (But probably later)- Energy is too low!- Will miss the critical point
Daniel Cebra @ APS DNP Meeting – Town MeetingNewport Beach, CA, 10/26/2012
Facility for Antiproton and Ion Research (FAIR)Time Line:SIS-100 is funded and will be complete by 2018SIS-300 will need additional funding (no time estimate)
Energy Range:SIS-100: Au+Au @ √sNN =2.9 GeVSIS-300: Au+Au √sNN = 2.7 - 8.2 GeV mB =0.730 - 0.410 GeV
Compressed Baryonic Matter (CBM)
STSMVD
TOF
TRDRICH
ECAL
++ Very High Interaction Rate- Fixed target geometry- No time estimate for SIS-300
Probably after 2022- Even with SIS-300, the energy is too low!- Will miss the critical point
Daniel Cebra @ APS DNP Meeting – Town MeetingNewport Beach, CA, 10/26/2012
SPS
NA61
2009
4.9-17.3
100 HZ
CP&OD
Facilty
Exp.:
Start:
Au+Au Energy:
Event Rate:
Physics:
RHIC BESII
STAR
2017
7.7– 19.6+
100 HZ
CP&OD
NICA
MPD
>2017?
2.7 - 11
<10 kHz
OD&DHM
SIS-300
CBM
>2022?
2.7-8.2
<10 MHZ
OD&DHM
√sNN (GeV)
At 8 GeV
PHENIX
CP = Critical PointOD = Onset of DeconfinementDHM = Dense Hadronic Matter
Comparison of Facilities
Fixed TargetLighter ion collisions
Fixed Target
Conclusion:RHIC is the best optionDaniel Cebra @ APS DNP Meeting – Town Meeting
Newport Beach, CA, 10/26/2012
H.J.Specht, Erice 2012 52
Beam conditions: CERN vs. GSI/FAIR
Luminosity at the SPS comparable to that of SIS100/300 No losses of beam quality at lower energies except for emittance growth RP limits at CERN in EHN1, not in (former) NA60 cave
< 11 – 35 (45) SPS SIS100/300
beam target interaction intensity thickness rate
2.5×106 5×105
[λi ] [Hz] [Hz]
20% NA60 (2003)
new injection scheme
108 10% 107 108 1% 106
interaction rate [Hz]
105 - 107
Energy range: 10 – 158 [AGeV]
LHC AA 5×104
Pb beams scheduled for the SPS in 2016-2017, 2019-2021
How to optimize the physics outcome for the next 10-15 y Proposal: split HADES and CBM at SIS-100
HADES at SIS-100
CBM at SPS
Upgrade HADES, optimized for e+e-, to also cope with Au-Au (now Ni-Ni)
Modify CBM to be optimal (magnet) for either e+e- or μ+μ-; role of hadrons?
Merge with part of personell of CBM
Merge with ‘CERN’ effort towards a NA60 successor experiment
Profit from suitable R&D of CBM
Profit from suitable R&D of CBM, in particular for Si
If SIS-300 would be approved in >2020, one could continue CBM there in >2027H.J.Specht, Erice 2012
G. Usai, CERN Town Meeting 2012
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SummaryResults from BES program covering large mB range
provide important constraint on QCD phase diagram.
Different features show up:– Proton v1 slope changes sign between 7.7 GeV and 11.5 GeV– Particles-antiparticles v2 difference increases with decreasing √sNN
– f-meson v2 deviates from others for √sNN ≤ 11.5 GeV
Search for the critical point continues:- Proposed BES-II program - Fixed target proposal to extend mB coverage up to 800 MeV
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Back up
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Chemical Freeze-out : Inelastic collision ceases Particle ratios get fixed
★THERMUS : Statistical thermal model Ensemble used – Grand Canonical and Strangeness Canonical
To consider incomplete strangeness equilibration:
Extracted thermodynamic quantities: Tch, mB, ms and gS •Thermus, S. Wheaton & Cleymans, Comput. Phys. Commun. 180: 84-106, 2009.
For Grand Canonical: Quantum numbers (B, S, Q) conserved on average
For Strangeness Canonical: Strangeness quantum number (S) conserved exactly
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Kinetic Freeze-out : Elastic collision ceases Transverse momentum spectra get fixed Blast Wave : Hydrodynamic inspired model
Extracted thermodynamic quantities: Tkin and <β>
E. Schnedermann et al., Phys. Rev. C 48, 2462 (1993)
Particle spectra are fitted simultaneously
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Lattice Gauge Theory (LGT) prediction on the transition temperature TC is robust.
LGT calculation, universality, and models hinted the existence of the critical point on the QCD phase diagram* at finite baryon chemical potential.
Experimental evidence for either the critical point or 1st order transition is important for our knowledge of the QCD phase diagram*.
* Thermalization has been assumed M. Stephanov, K. Rajagopal, and E. Shuryak,
PRL 81, 4816(98); K. Rajagopal, PR D61, 105017 (00) http
://www.er.doe.gov/np/nsac/docs/Nuclear-Science.Low-Res.pdf
The RHIC Beam Energy Scan Motivation
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STAR Preliminary
K/p
Particle Ratio Fluctuations
Monotonic behavior of particle ratio fluctuations vs. √sNN
STAR Preliminary
STAR Preliminary
p/p
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Higher Moments: Net-protons
0-5% central collisions: Deviations below Poisson observed for √sNN > 7.7 GeV Peripheral collisions: Deviations above Poisson observed for √sNN < 19.6 GeV Higher statistics needed at 7.7 GeV and 11.5 GeV and possibly a new data point around ~15 GeV
s /
S s ~ /
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Higher Moments: Net-charge
s /
S s ~ /
Data lies in between Poisson and HRG model expectations
Higher statistics needed at 7.7 GeV and 11.5 GeV and possibly a new data point around ~15 GeV
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(C) Searching QCD Critical Point
√sNN
observab
le Enhanced Fluctuationsnear Critical Point
T. Andrews. Phil. Trans. Royal Soc., 159:575, 1869
CO2 nearliquid-gas transition
Particle ratio fluctuations (2nd moments) - K/p, p/p, K/p Conserved number fluctuations - Higher moments of net-protons, net-charge,..
Peak magnetic field ~ 1015 Tesla ! (Kharzeev et al. NPA 803 (2008) 227)
CSE + CME → Chiral Magnetic Wave: • collective excitation• signature of Chiral Symmetry Restoration
RPaddN
ff
sin21
A direct measurement of the P-odd quantity “a” should yield zero.
S. Voloshin, PRC 70 (2004) 057901
Directed flow: expected to be the same for SS and OS
Non-flow/non-parity effects:largely cancel out P-even quantity:
still sensitive to charge separation
Chiral Magnetic effect + Local Parity Violation
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TPC:Detects Particles in the |h|<1 rangep, K, p through dE/dx and TOFK0
s, L, X, W, f through invariant mass
Coverage: 0 < f < 2p |h| < 1.0Uniform acceptance: All energies and particles
M. Šumbera NPI ASCR 67
Detector performance generally improves at lower energies.
Geometric acceptance remains the same, track density gets lower.Triggering required effort, but was a solvable problem.
Year √sNN [GeV] events(106)
2010 39 130
2011 27 70
2011 19.6 36
2010 11.5 12
2010 7.7 5
2012* 5 Test Run
BES-I Data:
Central Au+Au at 7.7 GeV in STAR TPC
Uncorrected Nch
dNev
t / (N
evt d
Nch
)BES Data Taking
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STAR TPC - Uniform Acceptance over all RHIC EnergiesAu+Au at 7.7 GeV Au+Au at 39 GeV Au+Au at 200 GeV
Crucial for all analyses
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Particle IdentificationPID (TPC+TOF):π/K: pT~1.6 GeV/cp: pT~3.0 GeV/cStrange hadrons: decay topology & invariant mass
TPC TPC+TOF
Au+Au 39 GeV
dE/d
x (M
eV/c
m)
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Charged Hadrons v1: Beam Energy Dependence
Scaling behavior in v1 vs. η/ybeam and v1 vs. η’=η-ybeam
Data at 62.4&200GeV from STAR, PRL 101 252301 (2008)
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Cou
nts
Cou
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nts
Cou
nts
2.94 2.96 2.98 2.94 2.96 2.98
Minv(He3+p )(GeV)2.94 2.96 2.98
Minv(He3+p )(GeV) Minv(He3+p )(GeV)3 3.02 3.04 3.06 3.08 3.1-
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2 / ndf 60.7 / 34Yield 42.11 14.00Mean 2.991 0.001
Run11 19 GeV minbias
STAR PreliminarySignal
rotated backgroundsignal+background fit
STAR Preliminarysignal
rotated backgroundsignal+background fit
STAR PreliminarySignal
rotated backgroundsignal+background fit
STAR PreliminarySignal
rotated backgroundsignal+background fit
STAR Preliminarysignal
rotated backgroundsignal+background fit
STAR Preliminarysignal
rotated backgroundsignal+background fit
Hypertriton Production
H + H produced at √sNN = 7.7, 11.5, 19.6, 27, 39, 200 GeV (minbias)3L
3L
_
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Phase Boundary Search With Nuclei
Needs higher statistics to make conclusive statement
Strangeness Population Factor:
Beam energy dependence of S3 behaves differently in QGPand pure hadron gas
- S. Zhang et al., PLB 684 (2010) 224
- J. Steinheimer et al.,PLB 714 (2012) 85
S3 indicates (with 1.7σ )
an increasing trend
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With 1st
order P.T.Without 1st
Order P.T.
Time evolution of the collision geometry
Kolb and Heinz, 2003, nucl-th/0305084
Initial out-of-plane eccentricity Stronger in-plane pressure gradients drive preferential in-plane expansion Longer lifetimes or stronger pressure gradients cause more expansion and more spherical freeze-out shape
We want to measure the eccentricity at freeze out, εF, as a function of energy using azimuthal femtoscopic radii Rx and Ry:
Evolution of the initial shape depends on the pressure anisotropy ● - Freeze-out eccentricity sensitive to the 1st order phase transition.
Non-monotonic behavior could indicate a soft point in the equation of state.
Spatial eccentricity
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Azimuthal HBT: First result
Is there a non-monotonic behavior?
sNN (GeV)
J. Phys. G: Nucl. Part. Phys. 38 (2011) 124148
x
75Is the discrepancy due to centrality or rapidity range? - NO
-1.0<y<-0.5-0.5<y<0.50.5<y<1.0
Azimuthal HBT: More Data
…and at LHC
For pT < 8 GeV/c: RAA for p and K are compatible and they are smaller than RAA for proton.For pT > 10 GeV/c: the RAA for p, K and proton are compatible within systematic error.
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RAA of neutral pions
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RAA(pT) of neutral pions
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RAA(pT) of neutral pions