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13-Jan-07
RHIC II Upgrade and Science Program
QCD Town MeetingRutgers, NJ
W.A. ZajcColumbia University
13-Jan-07
OutlineOutline
A capsule history of the initial discovery phase of RHIC operations
Compelling scientific questions
for RHIC II
The elements of RHIC II
The primacy of QCD
13-Jan-07
The Plan c. 2000The Plan c. 2000 Use RHIC’s unprecedented capabilities
Large √s Access to reliable pQCD probes Clear separation of valence baryon number and glue
Polarized p+p collisions
Two small detectors, two large detectors Complementary capabilities Small detectors envisioned to have 3-5 year
lifetime Large detectors ~ facilities
Major capital investments Longer lifetimes Potential for upgrades in response to discoveries
13-Jan-07
Since Then…Since Then… Accelerator complex
Routine operation at 2-4 x design luminosity (Au+Au) Extraordinary variety of operational modes
Species: Au+Au, d+Au, Cu+Cu, p+p Energies: 22 GeV (Au+Au, Cu+Cu, p), 56 GeV (Au+Au),
62 GeV (Au+Au,Cu+Cu, p+p) , 130 GeV (Au+Au), 200 GeV (Au+Au, Cu+Cu, d+Au, p+p), 410 GeV (p), 500 GeV (p)
Experiments Worked Collaborations worked
Science 160 refereed publications, 89(!) PRL’s Major discoveries
Future Demonstrated ability to upgrade Key science questions identified Accelerator and experimental upgrade program
developed to perform that science
13-Jan-07
A Non-Surprise: RHIC Energy Reduces Scale A Non-Surprise: RHIC Energy Reduces Scale DependenceDependence
The high √s of RHIC makes contact with rigorous pQCD calculations minimizes “scale dependence”
A huge advantage in Spin program Providing calibrated probes in A+A
PHENIX p+p 0 + X-NLO pQCD F. Aversa et al. Nucl. Phys. B327, 105 (1989)
-CTEQ5M pdf/PKK frag
-Scales =pT/2, pT, 2pT
=pT/2
=2pT
13-Jan-07
RHIC Spin SuccessesRHIC Spin Successes
BRAHMS & PP2PP (p)
STAR (p)
PHENIX (p)
AGS
LINACBOOSTER
Pol. Proton Source500 A, 300 s
Spin Rotators
Partial Siberian Snake
Siberian Snakes
200 MeV Polarimeter AGS Internal PolarimeterRf Dipoles
RHIC pC PolarimetersAbsolute Polarimeter (H jet)
2 1011 Pol. Protons / Bunch = 20 mm mrad
RHIC accelerates heavy ions to 100 GeV/A and polarized protons to 250 GeV
Achieved 60-65% polarization during RHIC Run-6 !
GeVs
L
50050
onPolarizati70%
cms102 2132max
13-Jan-07
Our First Hard Look Our First Hard Look
“Standard” value of g from pre-RHIC DIS data
Assuming g = 0
(x)g-(x)gΔg(x) -
13-Jan-07
RHIC’s Two RHIC’s Two MajorMajor Discoveries Discoveries Discovery of
strong “elliptic” flow: Elliptic flow in Au + Au
collisions at √sNN= 130 GeV, STAR Collaboration, (K.H. Ackermann et al.). Phys.Rev.Lett.86:402-407,2001
307 citations
Discovery of “jet quenching” Suppression of hadrons with
large transverse momentum in central Au+Au collisions at √sNN = 130 GeV, PHENIX Collaboration (K. Adcox et al.), Phys.Rev.Lett.88:022301,2002
357 citations
Flo
w s
tre
ng
thS
up
pre
sio
n F
acto
r
13-Jan-07
Thehottest densestmatter
ever studied in the laboratoryflows
as a (nearly) perfect fluidwith systematic patterns consistent with
quark degrees of freedom
and a viscosity to entropy density ratio lower (?) than any other known fluid with a value near (?) a conjectured
quantum bound
To SummarizeTo Summarize
T ~ 200- 400 MeV
i ~ 30-60 o
(thermal yields)
large “elliptic” flow
/s ~ (2-3) /4
valence quark scaling
13-Jan-07
See See SS Run Run The low viscosity is
“understood” as a result of Short mfp’s Large cross sections Strong coupling
near the phase “transition”
(really cross-over) Small /s sQGP
Strongly-coupledQuark-Gluon “Plasma”
“Perfect liquid"
We need to understand s when it is large!
“The strong coupling constant at low Q2”, A. Deur, hep-ph/0509188
“Perturbative QCD theory (includes our knowledge of s )”,
Y. Dokshitzer, hep-ph/9812252
13-Jan-07
How Perfect is “Perfect” ?How Perfect is “Perfect” ? All “realistic” hydrodynamic calculations for RHIC
fluids to date have assumed zero viscosity Viscosity= 0 “perfect fluid” But there is a (conjectured) quantum limit: “A Viscosity
Bound Conjecture”, P. Kovtun, D.T. Son, A.O. Starinets, hep-th/0405231
Where do “ordinary” fluids sit wrt this limit?
RHIC “fluid” mightbe at ~2-3 on this scale (!)
T=10T=101212 KK
sDensityEntropy
4
)(4
13-Jan-07
RHIC FutureRHIC FutureThe fundamental matter created at RHIC compels further
investigation How imperfect is its “perfection” ? How does it respond to truly heavy probes? (charm, bottom) Can even higher energy densities be achieved in U+U collisions? Is there a critical point in the QCD phase diagram ?
All of this (and more) is addressed by RHIC II: EBIS Electron Beam Ion Source to extend ranges of species Upgrades to STAR and PHENIX
Vertex detectors for precision heavy flavor tomography Increased coverage in forward regions Increased rate and triggering capabilities
x10 Luminosity increase by electron coolingx10 Luminosity increase by electron cooling Efficient access to the rare probes that have proven so incisive
in the first generation discovery measurements at RHIC.
13-Jan-07
Gold collisions (100 GeV/n x 100 GeV/n): no e-cooling with e-cooling
Ave. store luminosity [1026 cm-2 s-1] 8 70
Pol. Proton Collision (250 GeV x 250 GeV):
Ave. store luminosity [1032 cm-2 s-1] 1.5 5.0
Ongoing experiments and simulations in progress
RHIC II Luminosity Enhancement via e-RHIC II Luminosity Enhancement via e-CoolingCooling
13-Jan-07
Detector Upgrades Detector Upgrades
STAR PHENIX
forward meson spectrometerDAQ & TPC electronicsfull ToF barrelheavy flavor trackerbarrel silicon trackerforward tracker
Key:Completedongoingproposal submittedproposal in preparation
hadron blind detectormuon Triggersilicon vertex barrel (VTX)forward silicon forward EM calorimeter
Ongoing effort with projects in different stages
13-Jan-07
Fundamental Questions for Fundamental Questions for RHIC IIRHIC II
What are the phases of QCD Matter?
What is the wave-function of a heavy nucleus?
What is the wave-function of the proton?
What is the nature of non-equilibrium processes in a fundamental theory?
13-Jan-07
Compelling Physics of RHIC IICompelling Physics of RHIC II
High T QCD (A+A, d+A, and p+p): Electromagnetic radiation (e+epair continuum) Heavy flavor (c- and b-production) Jet tomography (jet-jet and -jet) Quarkonium ( J/, ’ , c and (1s),(2s),(3s) )
Spin structure of the nucleon: Quark spin structure q/q (W-production) Gluon spin structure g/g (heavy flavor and -jet
correlations)
Low x phenomena gluon saturation in nuclei
(particle production at forward rapidity)
Provide key measurements so far inaccessible at RHIC in three broad areas:
requires highestAA luminosity
All measurements require upgrades of detectors and/or RHIC luminosity
“Low x” “forward measurements”
13-Jan-07
What is the wave-function
of the proton?
13-Jan-07
Spin Goals for RHIC IISpin Goals for RHIC II Use the increased luminosity
to achieve a precision in g comparable to (at least) present knowledgeof :
Asymptotic expectation ( X. Ji, J. Tang, P. Hoodbhoy, Phys.Rev.Lett. 76, 740 (1996) )
Cleanest probe for g(x) : Prompt-photon production ( -jet, to determine parton kinematics ) Also the rarest, clearly benefits from increased luminosity RHIC II samples of ~ 1 fb -1 allow
Systematic cross checks (e.g., same x measured at variety of Q2 ) Extension to small x regions (using forward upgrades)
gq
proton
LgL 2
1
2
1
0.30.1Δq(x)dxq
ΔΣ
}
0.18163n
3n
2
1
f
f
}
163n
16
2
10.32
f
13-Jan-07
Sea quark/antiquark polarization Flavor decomposition likely to be
key to understanding small value of .
Major tool: Parity-violatingsingle-spin asymmetry AL from W ± decays.
Requires ~ 1 fb-1 data sets RHIC II luminosity Detector upgrades
Ultimate goal: charm-tagged W’s
Transverse spin measurements To study transversity To understand role of quark angular momentum To extract Sivers functions over unparalled range of x
and Q2 .
Spin Goals for RHIC II (Cont’d)Spin Goals for RHIC II (Cont’d)
13-Jan-07
What is the wave-function
of a heavy nucleus?
13-Jan-07
Rapidity Density600 1200
PHOBOS Central Au+Au (200 GeV)
Compilation by K. EskolaColor Glass
Kharzeev & Levin, Phys. Lett. B523 (2001) 79
Data: PHOBOS,Phys. Rev. Lett. 87, 102303 (2001)
From Eskola, QM 2000
A Surprise: RHIC Multiplicities Are A Surprise: RHIC Multiplicities Are “Low”“Low” Low, that is, compared to
pre-data predictions of “cascading partons”
Consistent with predictions based on gluon saturation :
13-Jan-07
AssertionAssertion In these complicated events, we have
(a posteriori ) control over the event geometry:
Degree of overlap Number of (nucleon) participants NPart
Orientation with respect to overlapReaction
Reaction
PlanePlane
““Central”Central” ““Peripheral”Peripheral”
23
dN/d
/ .5N
part
Saturation Saturation Running of Running of SS
)Part2
2S
2SSPart
CH log(N~)Λ
Qlog(~
)(Qα
1~
N
N
NPart
13-Jan-07
Fundamental Fields in NucleiFundamental Fields in Nuclei Nucleus increases saturation momentum scale QS 2 ~
(A/x)1/3
Occupation numbers ~ 1 / S(QS) > 1 This is the condition
for ~ classical fields: That is:
Quasi-classical states of the gluon field may be explored at low x in a nucleus
Exploration tools: Near-term: d+A collisions (RHIC RHIC II) Long-term: Electron-ion Collider
Goal: To understand
the wave-functionof a heavy nucleus
13-Jan-07
Relevance to Heavy Ion Relevance to Heavy Ion CollisionsCollisions
Lesson from RHIC:A+A collisionsare very efficientin translating Initial gluon state
Strong shadowing? Saturated gluons? Color Glass
Condensate?
intoFinal thermal state
It is difficult to understand this efficiency without invoking some form of dense gluonic initial state
We need to measure rather than invoke
13-Jan-07
What are the phases of QCD Matter?
What is the nature of non-equilibrium processes
in a fundamental theory?
13-Jan-07
Understanding the Understanding the MediumMedium Energy loss in a fluid:
☑ Jets travel faster than the speed of sound in the medium.
☑ While depositing energy via interactions with same
QCD “sonic boom” or “Mach cone”
To be expected in a dense fluid which is strongly-coupled
13-Jan-07
Observation of Mach Cone?Observation of Mach Cone? Seen in di-hadron correlation functions in : Modifications to di-jet hadron pair correlations in Au+Au
collisions at √sNN = 200 GeV, (S.S. Adler et al.), Phys.Rev.Lett.97:052301,2006
Sensitive to Speed of
sound Equation
of state
13-Jan-07
The Ultimate Calibrated ProbeThe Ultimate Calibrated Probe Extend the di-hadron correlations to
(direct) photon-hadron correlations Photons emerge directly, unaffected by the medium A clean measure of initial (hard) Q2
Heavy ion analog to tagged photon beam Current state of the art:
A potentially beautiful technique, desperately in need of RHIC II luminosities !
as compared
to
-h h-h
13-Jan-07
Heavy Flavor at RHIC IIHeavy Flavor at RHIC II Because the u, d, (s) current masses are small compared to T
Properties of the medium are(at zero baryon number)uniquely determined by T
But “introducing” heavy flavor establishes a new scale: Mc ~ 1.3 GeV Mb ~ 5.0 GeV
with associated length scales 1 / Mc ~ 0.15 fm 1 / Mb ~ 0.04 fm Flavor tagged jets to measure
Mach cones, heavy quark energy loss
Bohr radii (onium): J/ ~ 0.29 fm ~ 0.13 fm “Onium” spectroscopy
to measure plasma screening lengths
Measurements of such essential medium properties using rare probes becomes possible via RHIC II luminosities and the detector upgrades
RHICF
low
str
eng
th
13-Jan-07
The Promise of Heavy FlavorThe Promise of Heavy Flavor Present measurements
rely on detection of e’s, ’sfrom semi-leptonic decayof heavy flavor Little or no ability to determine
relative contributions of charm versus bottom
But recent results for Energy loss: RAA(pT) Flow : v2 (pT)
Strongly suggest
Similar estimates obtained from Light quark flow PT fluctuations
4)32(~
s
“Energy Loss and Flow of Heavy Quarks in Au+Au Collisions at √sNN = 200 GeV”, A. Adare et al., submitted to PRL, nucl-ex/0611018
“What do elliptic flow measurements tell us about the matter created in the little bang at RHIC?”, R. Lacey and A. Taranenko, nucl-ex/0610029
“Measuring Shear Viscosity Using Transverse Momentum Correlations in Relativistic Nuclear Collisions”, S. Gavin and M. Abdel-Aziz, nucl-th/0606061
13-Jan-07
Water Water RHIC RHIC Water Water RHIC RHIC The search for QCD phase transition of course
was informed by analogy to ordinary matter Results from RHIC are now “flowing” back to
ordinary matter
“On the Strongly-Interacting Low-Viscosity Matter Created in Relativistic Nuclear Collisions”,L.P. Csernai, J.I. Kapusta and L.D. McLerran, Phys.Rev.Lett.97:152303,2006, nucl-th/0604032
/
s
13-Jan-07
Is There a QCD Critical Point?Is There a QCD Critical Point? Here the analogy with phase transitions
in ordinary matter breaks down: Recall “ Properties of the medium are
(at zero baryon number)uniquely determined by T ”
Pressure = P(T) can’t vary independently(unlike water)
But if baryon number is non-zero (intensive order parameter) baryon chemical potential B :
To increase B : Lower collision energy Raise atomic mass
Both part of RHIC II
13-Jan-07
EBIS StatusEBIS Status EBIS Electron Beam Ion Source
Replaces tandems (thereby avoiding ~$9 M reliability investment)
Extends range of species (polarized 3He, noble elements, uranium )
Approved for construction CD-1 obtained $19.4M cost
($4.5M NASA) 3.5 yr schedule
FY06-09
New Physics!
(Next slide)
13-Jan-07
U+U collisionsU+U collisions Static deformation provides a way to vary the
‘other’ order parameter (baryon chemical potential B )
13-Jan-07
RHIC’s Energy Range Ideal For The RHIC’s Energy Range Ideal For The HuntHunt
There is considerable uncertainty in the location of the QCD critical point
RHIC RHIC II can make major advances on the “other” QCD front: U+U beams Comprehensive
detectors Collider superb control of systematics when changing √s Major importance when varying √sNN from 5 to 200 GeV !
RHIC II will be the ideal facility for systematically exploring the major region of the QCD phase diagram.
13-Jan-07
Heavy Ions at the LHCHeavy Ions at the LHC How could we not choose to investigate “QGP” at
every opportunity? LHC offers unparalleled
increase in √s Will this too create a
strongly-coupled fluid?
Active pursuit via Dedicated experiment (ALICE) Targeted studies (CMS,
ATLAS)
13-Jan-07
Heavy ion collisions at the LHC could reveal entirely new phenomena.
With RHIC II and LHC together we explore deconfined QCD matter over an unprecedented range …
With RHIC II e-cooling, the integrated luminosity per year is 36x larger at RHIC than LHC for heavy ions. From yesterday (Urs Wiedemann):
“The properties of the hot and dense QCD matter produced at the LHC may differ from those produced at RHIC. We can state already now that testing QCD evolution of properties of hot and dense QCD matter is of fundamental interest and is experimentally testable in an interplay of RHIC and LHC… Knowledge about (rare hard high-pT) probes at RHIC can be improved significantly with a luminosity upgrade, which thus could enhance the interplay between RHIC and LHC significantly (in particular if operational during the LHC discovery era).”
RHIC II will continue the demonstrated RHIC capabilities Precision probes Extended data runs Wide variety of beams and energies.
log
1/x
RHIC II and LHCRHIC II and LHC
13-Jan-07
From Urs Wiedemann From Urs Wiedemann (yesterday)(yesterday)
1. Results from the LHC heavy ion run will provide substantial novel tests for the key dynamical ideas (hydrodynamic behavior, hard parton propagation in matter, saturation) developed in the context of the RHIC heavy ion program. Consequence:
Any theory initiative (even if it aims primarily at meeting the challenges of the RHIC heavy ion program), must aim at an unbiased use of all experimental constraints. The most successful theory efforts will work towards a phenomenological framework testable in the entire energy range spanning RHIC and LHC.
2. The properties of the hot and dense QCD matter produced at the LHC may differ from those produced at RHIC. We can state already now that testing QCD evolution of properties of hot and dense QCD matter is of fundamental interest and is experimentally testable in an interplay of RHIC and LHC. Consequence:
We should recognize this novel opportunity. Rare hard high-pt probes provide the most versatile class of tools for characterizing properties of matter. Knowledge about these probes at RHIC can be improved significantly with a luminosity upgrade, which thus could enhance the interplay between RHIC and LHC significantly (in particular if operational during the LHC discovery era).
13-Jan-07
Long Term Timeline of Heavy Ion Long Term Timeline of Heavy Ion FacilitiesFacilities
2006 2012
RHIC
2009
LHC
FAIRPhase III: Heavy ion physics
QCD Laboratory at BNL
PHENIX & STAR upgrades
electron cooling “RHIC II”
electron injector/ring “e RHIC”
2015
Vertex tracking, large acceptance, rate capabilities
13-Jan-07
RHIC and RHIC II in World RHIC and RHIC II in World ContextContext
: 2009
: 2000RHIC II
: 2012
13-Jan-07
New DimensionsNew Dimensions Expanding our theoretical tools
Perturbative QCD (pQCD) for understanding jet quenching Lattice QCD (LQCD) for calculating static properties (s, ) Hydrodynamics as zero-mean-free-path limit of strong
coupling AdS/CFT for calculating static and dynamic properties of
strongly-coupled gauge theories Both sides of this equation
were calculated using black hole physics (in 5 dimensions)
RHICRHIC DensityEntropyityVis )(4
)cos(
Color Screening
cc
MULTIPLICITY
Entropy Black Hole Area
DISSIPATION
Viscosity Graviton
Absorption
13-Jan-07
New Dimensions in RHIC PhysicsNew Dimensions in RHIC Physics “The stress tensor of a quark moving through N=4
thermal plasma”, J.J. Friess et al., hep-th/0607022
Our 4-d Our 4-d worlworl
dd
String String theorist’theorist’
s 5-d s 5-d worldworld
The stuff The stuff formerly formerly known as QGPknown as QGP
Heavy Heavy quark quark
moving moving through through
the the mediummedium
Energy loss Energy loss from from string string dragdrag
Jet Jet modificationmodifications from wake s from wake
fieldfield
13-Jan-07
S G P S G P “Formerly known as quark-gluon plasma?” You can still use that label if you like, but- PARADIGM PARADIGM
SHIFTSHIFT RIHC does not produce asymptotically “free” quarks and
gluons Contrary to expectations (and announcements ! ), we did
not find evidence for “quarks (that) are liberated to roam freely”
The analogy to atomic plasmas is also strained: Atomic plasmas:
Can vary density and temperature independently Photon momentum-energy density (usually) irrelevant Can be strongly-coupled or weakly coupled
“QGP” One number (the temperature T ) determines all properties Intrinsically strongly-coupled fluid for any(?) accessible T
The matter created at RHIC could be called “S G P” S G P Sui Generis Plasma Sui generis : “Being the only example of its kind; unique ”
13-Jan-07
The Primacy of QCDThe Primacy of QCD While the (conjectured) bound
is a purely quantum mechanical result . . .
It was derived in and motivated by the Anti-de Sitter space / Conformal Field Theory correspondence
Weak form: “Four-dimensional N=4 supersymmetric SU(Nc) gauge theory is
equivalent to IIB string theory with AdS5 x S5 boundary conditions.”( The Large N limit of superconformal field theories and supergravity, J. Maldacena, Adv. Theor. Math. Phys. 2, 231, 1998 hep-th/9711200 )
Strong form: “Hidden within every non-Abelian gauge theory, even within the
weak and strong nuclear interactions, is a theory of quantum gravity.”( Gauge/gravity duality, G.T. Horowitz and J. Polchinski, gr-qc/0602037 )
Strongest form: Only with QCD can we explore experimentally these fascinating connections over the full range of the coupling constant to study QGP
4
s
Quantum Gauge Phluid
13-Jan-07
RHIC Scientific FutureRHIC Scientific Future Fundamental Strings(??)
Fundamental Particles Understand the spin structure of the nucleon p+p at RHIC, RHIC II, …. Polarized e-p collider
Fundamental Fields Understand the wave-function of a heavy nucleus d+A at RHIC, RHIC II, …. Electron-ion collider
Fundamental Matter Understand the phase diagram of QCD A+A at RHIC, RHIC-II, LHC, FAIR