wit busza doe review of rhic program 9 july 2003
TRANSCRIPT
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Wit Busza
DoE Review of RHIC Program
9 July 2003
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Collaboration
Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Bruce Becker, Russell Betts, Abigail Bickley, Richard Bindel, Andrzej Budzanowski, Wit Busza (Spokesperson), Alan Carroll,
Patrick Decowski, Edmundo Garcia, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Stephen Gushue, Clive Halliwell, Joshua Hamblen, Adam Harrington, Conor Henderson,
David Hofman, Richard Hollis, Roman Holynski, Burt Holzman, Aneta Iordanova, Erik Johnson, Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo, Jang Woo Lee, Willis Lin, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Aaron Noell, Rachid Nouicer, Andrzej Olszewski,
Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed, Louis Remsberg, Christof Roland, Gunther Roland, Joe Sagerer, Pradeep Sarin, Pawel Sawicki, Iouri Sedykh, Wojtek Skulski,
Chadd Smith, Peter Steinberg, George Stephans, Andrei Sukhanov, Ray Teng, Marguerite Belt Tonjes, Adam Trzupek, Carla Vale, Robin Verdier, Gábor Veres, Bernard
Wadsworth, Frank Wolfs, Barbara Wosiek, Krzysztof Wozniak, Alan Wuosmaa, Bolek Wyslouch, Jinlong Zhang
ARGONNE NATIONAL LABORATORYBROOKHAVEN NATIONAL LABORATORYINSTITUTE OF NUCLEAR PHYSICS KRAKOWMASSACHUSETTS INSTITUTE OF TECHNOLOGYNATIONAL CENTRAL UNIVERSITY, TAIWANUNIVERSITY OF ILLINOIS AT CHICAGOUNIVERSITY OF MARYLANDUNIVERSITY OF ROCHESTER
To date: 3 PhDs
Currently:16 PhD students
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dN
ch/d
4-detector strategy for the initial RHIC program has turned out to be excellent:
•Adequate overlap
- Impressive agreement between all experiments
•Complementary
PHOBOS Mission
Flexibility to Respond to First Results
Low Pt Phenomena
Early “Big Picture”
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We would have liked
•More data
•Energy scan
•Species scan
•A larger BNL Group
Bottom line:
RHIC environment has been good for PHOBOS
•Strong support
-from management
~for BNL Group
~for 20 GeV Run
-from CAD
Result:
•PHOBOS has achieved to date more than we could have hoped for
• >50% of our mission complete
BUT
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*Charged particle multiplicity near mid-rapidity in central Au+Au collisions at √sNN = 56 and 130 AGeV Phys. Rev. Lett. 85, 3100 (2000) {first published results from RHIC data}
* Ratios of charged particles to antiparticles near mid-rapidity in Au+Au collisions at √sNN =130 GeV Phys. Rev. Lett. 87, 102301 (2001)
*Charged-particle pseudorapidity density distributions from Au+Au collisions at √sNN =130 GeV Phys. Rev. Lett. 87, 102303 (2001)
*Centrality Dependence of Charged Particle Multiplicity at Midrapidity in Au+Au Collisions at √sNN =130 GeV Phys. Rev. C65, 31901R (2002).
*Energy dependence of particle multiplicities near mid-rapidity in central Au+Au collisions Phys. Rev. Lett. 88, 22302 (2002) {first published results from data at maximum energy}
*Centrality Dependence of the Charged Particle Multiplicity near Mid-Rapidity in Au+Au Collisions at √sNN =130 and 200 GeV Phys. Rev. C65, 061901R (2002).
*Pseudorapidity and centrality dependence of the collective flow of charged particles in Au+Au collisions at √sNN =130 GeV Phys. Rev. Lett. 89, 222301 (2002)
*Ratios of charged antiparticles to particles near mid-rapidity in Au+Au collisions at √sNN =200 GeVPhys. Rev. C 67, 021901R (2003)
*The significance of the fragmentation region in ultrarelativistic heavy ion collisionsPhys. Rev. Lett (In press).
*Comparison of the Total Charged-Particle Multiplicity in High-Energy Heavy Ion Collisions with e+e- and pp/pbar-p DataSubmitted to Phys. Rev. Lett.
*Charged hadron transverse momentum distributions in Au+Au collisions at √sNN = 200 GeVSubmitted to Phys. Lett.B
*Centrality Dependence of the Charged Hadron Transverse Momentum Spectra in d+Au Collisions at √sNN =200 GeV Submitted to Phys. Rev. Lett. {jointly with STAR and PHENIX, first results from dAu run}
>400 citations
>150 citations first paper
>36 citations/paper
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SPECTRIG
T0
T0
mini-pCal
pCal
i. Moved TOF walls back
• 5 m from interaction point
ii. New on-line high pT Spectrometer Trigger
iii. New “time-zero” (T0) Cerenkov detectors • On-line vertexing and ToF start time
iv. Forward proton calorimeters on Gold and
Deuteron sides
v. DAQ upgrade (x10)
4π Multiplicity Detector
2 Arm Multiparticle Spectrometer
Response to Importance of High PT Studies
For 2003 run
Flexibility to respond to results:
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What is the “Big Picture” as seen by PHOBOS?
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PHOBOS 130 GeV
PRL 87,102301,2001
p/p
K–/K+
PHOBOS 200 GeV
PRC 67, 021901(R), 2003
A+A central collisions
Baryon density at mid-rapidity rapidly decreases with energy
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11
451000~
alld
dN
GeVE 1~
Initially released energy density >5GeV/fm3
Note: energy density inside proton ≈ 0. 5GeV/fm3
32 200~)1(~ fmfmR
Total energy released ~2000GeV
Max. initial overlap volume
Energy density high; system must be partonic
Nu
mb e
r o f
Pa r
t icl
es P
rod
u ce d
at
y=0
Energy of Collision
crossover
PRL 88, (2002) 22302
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PHOBOS preliminary
h+ + h-
200 GeV Au+Au
0<<1.5
(top 55%)
v 2
17% scale error
Peripheral Central
Medium is highly interactive
Elliptic flow:PRL 89 (2002) 222301
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Au+Au sNN=200 GeV 15% central-0.1< y <0.4
(++)
(K+
+K–)
(p+p)
PHOBOS preliminary
pT [GeV/c]
1/
(2p
T)d
2N
/dyd
pT
Very few low momentum particles because of flow
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Jet-quenching: further evidence that medium interacts strongly and that parton density is very high.
0.2<y<1.4
Data: PHOBOS, nucl-ex/0302015Submitted to Phys Lett B
peripheral
central
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central Au+Au
All syst. uncertainties: 90% C.L.
PHOBOS d+Au: nucl-ex/0306025, submitted to PRL
Jet-quenching is not an initial state effect!
central dAu
recent
dAu
data
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Comparisons with models
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Rapidity Density600 1200
PHOBOS Central Au+Au (200 GeV)
Compilation by K. EskolaColor Glass
Hadron multiplicities at RHIC well described by Parton Saturation
Particle Multiplicity
Kharzeev & Levin, Phys. Lett. B523 (2001) 79
Data: PHOBOS,Phys. Rev. Lett. 87, 102303 (2001)
From Eskola, QM 2000
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dAu data disfavor initial state interpretation of Au+Au high-pT suppression
For example,
Vitev(pQCD) predicts 15% increase Kharzeev, Levin, McLerran (parton saturation) predict 25-30% decrease over this range of centrality
PHOBOS d+Au: nucl-ex/0306025, submitted to PRL
All syst. uncertainties: 90% C.L.
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Some surprises
Accidental, trivial or profound?
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Collision viewed in rest frame of CM:
19.6 GeV 130 GeV 200 GeVPHOBOS PHOBOS PHOBOS
Central Collisions
Peripheral Collisions
dNd
PHOBOS Au+Au
dN
ch/d
/<
Np
art>
/26% central
beamy
p + p
dN
/d
UA5
beamy
Collision viewed in rest frame of one nucleus:
Limiting fragmentation is valid in AA collisions!
PRL in press
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200GeV 130GeV
19.6GeV (PRELIMINARY)
Au+Au yields normalized to corresponding pp value for all three
energies
pp Errors from Au+Au only
PHOBOS Au+Au
19.6 GeVpreliminary
130 GeV
200 GeVPRC 65 (2002) 061901R
pp
Scaling with Npart of midrapidity multiplicity inconsistent with naïve expectations:
Slow quark
Fast quark
Data inconsistent with the following picture:
Midrapidity||<1
dN
ch/d
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Preliminary v2200
Final v2130
PHOBOS Au-Au
v 2
200 GeV
130 GeV<Npart>~190
Flow is anything but boost invariant!
PRL 89, 222301
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Au+Au
)/exp( sBsch CAN
Nu
mb e
r o f
Pa r
t icl
es P
rod
u ce d
Energy of Collision
Amazing similarity of multiplicity in e+e- and AA collisions
e+e-
Submitted to PRL
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PHOBOS, nucl-ex/0302015,submitted to Phys. Lett. B
Why high PT particle yield scales approximately with Npart?
Is medium completely opaque?
Are high PT particles emitted only from surface?
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PHOBOS Research program is >50% completed
What are the needs to complete PHOBOS mission?
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At what energy does jet-quenching switch off?
1. Energy scanWhere located?
Submitted to Phys. Lett. B
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2. Species scan
AuAu dAu
Also needed for better understanding of the geometry of the collision, in particular for peripheral collisions
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3. More AuAu data at maximum energy for fluctuation studies, K+K-, etc.
4. More pp at 200 GeV and pp at 400-500 GeV-baseline for comparisons with AuAu
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Summary• 4 detector strategy is working well
– Where there is overlap, impressive agreement between all detectors
• RHIC environment has given PHOBOS the opportunity to complete >50% of its planned research program
• PHOBOS collaboration served well by the BNL PHOBOS Group– In operations
– In data handling
– In physics analysis
• The contribution of PHOBOS to the RHIC mission – Major contribution in obtaining early on in the program the “Big Picture”
– Observation of several unexpected results• Scaling properties
• Similarities with e+e- collisions
– Pioneered the use of ROOT, (and more recently PROOF) in HI community
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•Unfinished parts of PHOBOS mission–High statistics AuAu and pp runs @ 200 GeV–Species scan–Energy scan –pp at 400 or 500 GeV
•Phobos has some unique capabilities-we would like to finish the program in a timely fashion
Summary continued