Nuclear modification factor for identified hadrons at forward rapidity in Au+Au

reactions at 200GeVRadoslaw Karabowicz

for the BRAHMS Collaboration

Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland

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Data analyzed:Au+Au, p+p at sqrt(s_NN)=200GeV

BRAHMS experiment

Tracking Detectors

Magnets

3

RICH Pid

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RICH Pid – 3 sigma cut. In the overlapping regions Pid based on statistical weighting of Gaussian distibution in r.

p [GeV/c]

r [c

m]

m2 [GeV2/c4]

4 4

Au+Au 200 AGeV pions

y-pT map coverage

Different colors –different angle and

field settings - trigger normalization- acceptance- tracking efficiency- Pid efficiency

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pT spectra

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RCP in Au+Au @ 200 AGeV

RCP [(d2NAu+Au/dpTdy)/<Ncoll>]0-

10%[(d2NAu+Au/dpTdy)/<Ncoll>]40-

50%

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RAA in Au+Au @ 200 AGeV

Increase of ratios with decreasing

centrality

Pions and kaons ratios flat

Protons show Cronin peak at pt=2

RAA d2NAu+Au/dpTdy

<Ncoll> d2Nppinel/dpTdy

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RAA comparison with RCP

RCP and RAA are consistent for pions

and kaons

For protons RCP shows suppression, while RAA shows enhancement

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RAA for pions at forward

rapidities agrees

with RAA at midrapidit

y

RAA at y=0 and y=3.1

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RCP for pions at forward

rapidities copies the behaviour of RCP at

midrapidity

RCP at y=0 and y=3.1

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For protons however data

at forward rapidity show

significant suppression

in RCP

RCP at y=0 and y=3.0

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RdAu compared with RAA

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• identified particle yields has been measured by BRAHMS at forward rapidity for Au+Au and p+p collisions

• RAA shows significant suppression for pions and kaons, but for protons it shows enhancement

• RCP and RAA are consistent for pions and kaons, but deviate for protons

• no difference in pion RAA between midrapidity (PHENIX 0) and forward rapidity (BRAHMS ++-/2) consistent with surface jet-emission

• baryons’ RCP shows suppression at forward rapidities in contrast with midrapidity

• pions RAA shows stronger suppression as compared to RdAu

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SUMMARY

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The BRAHMS CollaborationI.Arsene11, I.G. Bearden6, D. Beavis1, S.Bekele10, C. Besliu9, B. Budick5, H.

Bøggild6 ,

C. Chasman1, C. H. Christensen6, P. Christiansen6, R.Clarke9, R.Debbe1,

J. J. Gaardhøje6, K. Hagel7, H. Ito1, A. Jipa9, J. I. Jordre9, F. Jundt2, E.B.Johnson10,

J.I.Jordre8, C.Jørgensen6, R. Karabowicz3, E. J. Kim10, T.M.Larsen6, J. H. Lee1,

Y. K.Lee4, S.Lindal11, G. Løvhøjden2, Z. Majka3, M. Murray10, J. Natowitz7, B.S.Nielsen6,

D.Ouerdane6, R.Planeta3, F. Rami2, C.Ristea6, O.Ristea9,

D. Röhrich8, B. H. Samset11, S. J. Sanders10, R.A.Sheetz1, P. Staszel3, T.S. Tveter11,

F.Videbæk1, R. Wada7, H.Yang8, Z. Yin8, and I. S. Zgura9

1Brookhaven National Laboratory, USA, 2IReS and Université Louis Pasteur, Strasbourg, France3Jagiellonian University, Cracow, Poland,

4Johns Hopkins University, Baltimore, USA, 5New York University, USA6Niels Bohr Institute, University of Copenhagen, Denmark

7Texas A&M University, College Station. USA, 8University of Bergen, Norway 9University of Bucharest, Romania, 10University of Kansas, Lawrence,USA

11 University of Oslo Norway

48 physicists from 11 institutions