Dec 18, 2001Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute1 nFirst physics at RHIC with 65 AGeV + 65 AGeV and 100 AGeV + 100 AGeV Au+Au collisions:

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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First physics at RHIC with 65 AGeV + 65 AGeV and 100 AGeV + 100 AGeV Au+Au collisions: THE LITTLE BIG BANG

Ecm= s 40 TeV

4000-5000 charged particles produced per collision

Transparency or Stopping ?

Towards nuclear ’stuff’ with matter-antimatter balance

BRAHMS Y2000 + Y2001 @ RHIC: snn=130 GeV, and snn=200 GeV

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Quark Gluon PlasmaHot and dense matter

QGP

HG

Freeze out

Hadron gas

Mixed phase

QGP

Pre-equil. quark

2.1012K

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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The particle ZooBasic ’animals’

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Quark ’Lego’. Hadrons

Weak decay

Hadronic interactionStrange

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Confinement, jets, asymptotic freedom, color ropes etc…

The quarkonium potential

2mqc2

Hadron

Hadron

Meson

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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URQMD simulation of Au+Au at snn=200 GeV

Rapidity y = ½ ln (E+pz / E- pz) = ½ ln(1+cos / 1-cos) y(lab) = y + y(cm)

Pseudorapidity = ln (cot [/2])

Transverse momentum pt= p sin

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Central Au+AU collision event in STAR

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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RHIC physicsAugust 2000 & August 2001

2:00 o’clock

4:00 o’clock6:00 o’clock

8:00 o’clock

10:00 o’clock

STARPHENIX

RHIC

AGS

LINACBOOSTER

TANDEMS

9 GeV/uQ = +79

1 MeV/uQ = +32

HEP/NP

g-2

U-lineBAF (NASA)

BRAHMS: Lpeak = 3.3 1025 cm-2 s-1

Lave = 1.7 1025 cm-2 s-1

Rcoll= 350 HzPHOBOS

6 b-1

2 wks

August 2000 and 2001

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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BRAHMS in the 2’ hall

… in 1998

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Forward & Midrapidity spectrometers in 2001

FS: 2 TPC, 2 TOF, C1-threshold, 3 Drift Ch. Mod., RICH, 4 Dipoles

2.5 - 30 deg. = 1.5 - 4

MRS: 2 TPC, 1 Dipole, 1TOF

30 - 90 deg. = 0 - 1.5

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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I.G. Bearden7, D. Beavis1, C. Besliu10, Y. Blyakhman6, J. Bondorf7, J.Brzychczyk4, B. Budick6, H. Bøggild7, C. Chasman1, C. H. Christensen7, P. Christiansen7, J.Cibor4, R.Debbe1, J. J. Gaardhøje7, M. Germinario7, K. Grotowski4, K. Hagel8, O.

Hansen7, H. Heiselberg7, A. Holm7, A.K. Holme12, H. Ito11, E. Jacobsen7, A. Jipa10, J. I. Jordre10, F. Jundt2, C. E. Jørgensen7, T. Keutgen9, E. J. Kim5, T. Kozik3, T.M.Larsen12, J.

H. Lee1, Y. K.Lee5, G. Løvhøjden2, Z. Majka3, A. Makeev8, B. McBreen1, M. Murray8, J. Natowitz8, B.S.Nielsen7, K. Olchanski1, D. Ouerdane7, R.Planeta4, F. Rami2, D.

Roehrich9, B. H. Samset12, S. J. Sanders11, D. Sandberg7,I. S. Sgura10, R.A.Sheetz1, Z.Sosin3, P. Staszel7, T.S. Tveter12, F.Videbæk1, R. Wada8 and A.Wieloch3.

1Brookhaven National Laboratory, USA 2IReS and Université Louis Pasteur, Strasbourg, France

3Jagiellonian University, Cracow, Poland 4Institute of Nuclear Physics, Cracow, Poland 5Johns Hopkins University, Baltimore, USA

6New York University, USA 7Niels Bohr Institute, Blegdamsvej 17, University of Copenhagen, Denmark 8Texas A&M University, College Station. USA

9University of Bergen, Norway 10University of Bucharest, Romania

11University of Kansas, Lawrence,USA 12 University of Oslo Norway

BRAHMS Intl. collaboration

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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First BRAHMS collision at 100 AGeV+100AGeV

T1

MTPC1

T2

MTPC2

MRS: 90 deg

6.5 msr

FS: 6 deg

0.8 msr

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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BRAHMS acceptance Y2000 & Y2001

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Centrality determinationVertex distribution

1m

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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TPC tracks, Vertex reconstruction, Charged particle track density

MTPC1

z

y

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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dNch/d @ snn= 130 GeVSiMA, TMA, BB, TPC

N=dE /<dE> P(0)/P(n1) Background corr.due

to secondaries (37-50%)

Consistency between 4 independent detector systems

65 AGeV+ 65 AGeV: N(ch)d= 3860±300 Central 0-5% dN(ch)/d (=0) =550 FWHM of distribution

= 7.6 0.7

0-5%

10-20%

20-30%

30-40%

40-50%

5-10%

600

BRAHMS Phys. Lett. B 523 (2001) 227; nucl-ex 0108015

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Background…A slight complication

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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RHIC: 200 AGeVWill this happen?

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Whirlpool Galaxy. M51, Hubble space telescope

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Pseudorapidity densities@ 200 AGeV

5630 charged particles produced for 0-5% central

14% increase over 130GeV 50% increase over p +p (UA5) => significant medium effects

Bjorken energy density

BJ = (1/R20) dEt/d 5 GeV/fm3

dEt=dN • <pt>

cf: QGPcritical 1 GeV/fm3

Brahms 200

pp

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Hard and Soft vs.High Density QCD @ 200 AGeV

Kharzeev and Levin (nucl-th/0108006)

HIGH DENSITY QCD MODEL

Soft-Hard: dN/d=(1-X) npp <Npart>/2

+ X npp <Ncoll>

<Ncoll>=1049, <Npart>=339, npp=2.43 =>dN/d=668 (with X=0.9)

High Density QCD-saturation:

dN/dy = f( Npart, Qs

2, ,QCD,s,y)

with =0.3 from HERA data => dN/d=620 (using dN/d=549 at

s=130GeV)

BRAHMS

Submitted to PRL dec. 2001

Nucl-ex. 00112001

=4.5

=3.0

=0

Gluon saturation ?

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Saturation of excitations in fragmentation region

Shift data to beam frame of reference

BRAHMS subm. to PRL- n-ex. 00112001

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Hadron identification MRS (90 - 40 deg). TOF

m2=p2( t2 / L2 -1)

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Hadron IdentificationFS (4-20deg @200AGeV)

C1,H1,T2

+

p

K+

4 deg

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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C1 Threshold CherenkovPID

Cos=1/n

=>

th=1/n

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Ring Imaging Cherenkovfor high momentum PID

R

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Antiparticle/particle ratios @ 200AgeV

’+’ ’-’

p-/p = p-(pair) / [p+p(pair)]

K-/K+ = K-(pair) / [K+(pair)+K+(ap)]

(p+p p++K+)

+- pair prod (& ch. exch).

Midrapidity: near matter-antimatter balance

+ +

BRAHMS Preliminary

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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How consistent are the models @ snn= 130GeV?

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Summary: First Au+Au snn=130 & 200 GeV

Highest particle multiplicity in nuclear collisions ( 4600 ch. part) ever seen

Large(st) energy density > 5 crit

High reaction transparency Decoupling of central and

’fragmentation’ regions Partonic (color) description

appears necessary Central region dominated by matter-antimatter balance:

Qualitatively new physics regime

To come: Strangeness, fluctuations, net baryon density, jet quenching, ….

2006: ALICE @ LHC -CERN

snn=6000 GeV, Pb+Pb

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Extra’s

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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ALICE at LHC point 2CERN

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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ALICE TPC

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Pbar/p ratio systematics

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Fluctuations in particle production

Fluctuations in multiplicity

= (<N2>-<N>2 ) / <N>

Participant model:

<N>= <n> <Np>

= (int) + N . (Np)

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Intrinsic fluctuations in particle production

=(int)+(b)+(mom)+(second)+(vertex)

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Multiplicity 200 AGeV / 130 AGeV

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Electromagnetic nuclear dissociation

LO+NLO Mutual EM

•Mutual Electromagnetic dissociation

•(Spectrum of virtual photons) * (absorption cross section) = WW

•Multiphonon GDR excitation, abs

•EM vs Nuclear coll.

•=> neutron (L*R) coincidences

•RELDIS. Pshenichnov, JPB, IM, et al.

EM dissociation selected by ZDC coincidences

and TMA Veto in BRAHMS

n

n n

2n

1n

LO

NLO

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Neutral Energy correlations (ZDC)

C2(EL,ER)=P(EL,ER)/(P(EL)*P(ER))

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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N(p-bar)/N(p) systematics vs CM energy

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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StrangenessK-/K+ vs y @ snn= 130GeV

BRAHMS Preliminary

CERN-SPS

Dec 18, 2001 Odense Uni., Jens Jørgen Gaardhøje, Niels Bohr Institute

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Bjorken limit reached for Au+Au snn= 130GeV?

ISR R803

s=23

s=63

BRAHMS

PRL87(2001)112305