brahms y2000 + y2001 @ rhic: s nn =130 gev, and s nn =200 gev
DESCRIPTION
BRAHMS Y2000 + Y2001 @ RHIC: s nn =130 GeV, and s nn =200 GeV. Reaction features in 65 AGeV + 65 AGeV and 100 AGeV + 100 AGeV Au-AU collisions EM dissociation dN(ch)/d distribution -4TRANSCRIPT
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 1
Reaction features in 65 AGeV + 65 AGeV and 100 AGeV + 100 AGeV Au-AU collisions
EM dissociation dN(ch)/d distribution -
4<<4 vs. Collision Centrality
Production of charged particles, N(ch)/pr.participant
Bjorken limit attained ? Transparency or Stopping
p-bar/p vs y, b, pt
Strangeness vs y Future
BRAHMS Y2000 + Y2001 @ RHIC: snn=130 GeV, and snn=200 GeV
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 2
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, 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, 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
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 3
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
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 4
BRAHMS in the 2’ hall
… in 1998
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 5
Forward & Midrapidity spectrometers
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
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 6
First BRAHMS collision at 100 AGeV+100AGeV
T1
MTPC1
T2
MTPC2
MRS: 90 deg
6.5 msr
FS: 6 deg
0.8 msr
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 7
BRAHMS acceptanceAugust 2000 & 2001
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 8
Global detectorsSiMA, TMA, BB
SiMA (-2.0< <2.0) PTMA (-2.2< <2.2) Beam-Beam (3 < | | < 4)
97% (geom)
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 9
Centrality determinationVertex distribution
1m
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 10
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
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 11
Neutral Energy correlations (ZDC)
C2(EL,ER)=P(EL,ER)/(P(EL)*P(ER))
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 12
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= 4050±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 Subm. Phys. Lett. B 7/2001.
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 13
TPC tracks, Vertex reconstruction, Charged particle track density
MTPC1
z
y
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 14
Charged Particle Mult.snn=130 GeV
BRAHMS. Subm. to Phys Lett. B. 2001
SPS
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 15
NCharged vs. number of participant nucleon pairs. snn=130AGeV
dN/d 3 (=0) pr.part pair. Cf. HIJING, FRITIOF No saturation effects
observed
Claus Ekman Jørgensen.
Thesis NBI 2001
FRITIOF
HIJING
MTPC1 CEJ
EKRT
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 16
RHIC: 200 AGeVWill this happen?
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 17
dNch/d for100 AGeV + 100 AGeV
100 AGeV + 100 AGeV Au+Au
N(ch)d= 5100±300 Central 0-6% dN(ch)/d (=0) =61050 FWHM of distribution
= 7.9 1.0
BRAHMS 200AGEV
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 18
Hard and Soft vs.High Density QCD @ 200 AGeV
Kharzeev and Levin (nucl-th/0108006)
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)
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 19
Total production of Charged particles
130 AGeV 4000 charged part. observed Nch 23.5 pr. part. pair cf. Nch 17 in p+p at s=130GeV 35-40% increase over p+p
Syst
?BRAHMS
200 AGeV 130AGeV
200 AGeV 5100 charged part. observed Nch 30 pr. part. pair cf. Nch 20 in p+p at
s=200GeV 50% increase over p+p
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 20
Hadron identification MRS (90, 40 deg)
m2=p2( t2 / L2 -1)
p-bar
K p
=0
=3
p
K
0
p, pbar
K±
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 21
Hadron IdentificationFS (4 deg & 130AGeV)
p-bar
=3
C1,H1,T2
+
p
m2=p2( t2 / L2 -1)
+
p
K+
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 22
N(pbar)/N(p) @ 130 AGeV Centrality and Pt dependence
Antiproton absorbtion correction to pbar/p ratio:
5 % for FS at 4 deg 2 % for MRS at 90, 40 deg 10% corr. (low pt) p from Be-
tube Applied to data
Most pbar and p from Hyperon decays fall into spectrometer acceptance.
Correction factor depends on H/B, H-bar/B-bar and TB/TH
For H/B < 0.5 systematic correction is < 5% on ratio
Model dependent not applied to data
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 23
Bjorken limit reached for Au+Au snn= 130GeV?
ISR R803
s=23
s=63
BRAHMS
PRL sept. 2001
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 24
FS Hadron identificationfor snn = 200 GeV Au+Au
TOF and Cherenkov veto in FFS
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 25
Particle ratios snn = 200 GeV (y=2)
Y=2 : p-bar/p = 0.48 0.08 -/+= 0.98 0.04
BRAHMS: Preliminary Integrated over centrality and
pt rangeK- p-
K+ p
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 26
N(p-bar)/N(p) systematics vs CM energy
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 27
StrangenessK-/K+ vs y @ snn= 130GeV
BRAHMS Preliminary
CERN-SPS
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 28
How consistent are the models @ snn= 130GeV?
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Sept 4, 2001 Paris, Jens Jørgen Gaardhøje, Niels Bohr Institute 29
Summary: First Au+Au snn=130 & 200 GeV
RESULTS: 100+100 Nch (0-5%) 5100 dN/d (y=0) 625. FWHM 7.8 N(ch) 30 pr. participant-pair dN/d (y=0) 3.6 pr. part. Pair
p-bar/p = 0.48 (y=2) Moderate growth in baryon
poor ’plateau’. Total mult. Increases by 25%, Central mult increases by 14% Pbar/p increases by 17% (y=2)
Large y and pt coverage to come
RESULTS: 65+65 Nch (0-5%) 4000 dN/d (y=0) 550. FWHM 7.6 N(ch) 23 pr. participant-pair dN/d (y=0) 3 pr. part. Pair
AntiMeson/Meson close to unity
p-bar/ p vs y shows increased but still incomplete transparency
Midrapidity Plateau? y =0,0.7,2 : pbar/p 0.64, 0.66,
0.41 (±0.05 ± 0.06) Weak pt and centrality
dependence Bjorken limit not reached Models inconsistent with data