Is there more than one source

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Is there more than one source?

• I. Arsene, I.G. Bearden, D. Beavis, C. Besliu, B.
  Budick, H. Bøggild, C. Chasman,
• C. H. Christensen, P. Christiansen, J. Cibor, R.
  Debbe, E. Enger J. J. Gaardhøje,
• M. Germinario, K. Hagel, O. Hansen, A. Holme,
  A.K. Holme, H. Ito, A. Jipa,
• J.I. Jørdre, F. Jundt, C.E.Jørgensen, R.
  Karabowicz, E.J. Kim, T. Kozik,
• T.M. Larsen, J.H. Lee, Y. K.Lee, S. Linda, G.
  Løvhøjden, R. Lystad, Z. Majka,
• A. Makeev, M. Mikelsen, M. Murray, J. Natowitz,
  B. Neumann, B.S. Nielsen,
• K. Olchanski, D. Ouerdane, R.Planeta, F. Rami, C.
  Ristea, O. Ristea, D.Röhrich,
• B. H. Samset, D. Sandberg, S. J. Sanders,
  R.A.Sheetz, P. Staszel, T.S. Tveter,
• F.Videbæk, R. Wada,Z. Yin and I. S. Zgura
• Brookhaven, Strasbourg, Krakov, Johns Hopkins,
  NYU, Niels Bohr.
• Texas AM, Bergen, Bucharest, Kansas, Oslo

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This talk is dedicated to Julia Thompson who
worked to bring S. African teachers into physics
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Outline

• Overview of experiment and data.
• Advantages of studying rapdity dependence
• Blast wave vs y
• Chemical analysis vs y
• Limiting fragmentation
• AuAu vs pp systematics

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Identifying high rapidity particles
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Why study rapidity dependence?

• At y0 we seem to have a hot and dense system
• how far in rapidity does it persist?
• How far back from ybeam do saturation effects
  persist?
• We also hope to understand the longitudinal
  dynamics of the source and measure the total
  energy loss, multiplicity strangeness etc.
• We may find that there is more than one source,
  i.e. different parts of the system lose causal
  contact.

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Spectra vs. Pt and rapidity
PT
AuAu 10 Central
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Spectra vs. Rapidity
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How quickly do things change?
Blast wave parameters have a stronger dependence
on rapidity than on centrality
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Yield and ltpTgt vs Rapidity
AuAu 5
See Ouerdane talk and nucl-ex/0403050
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Rapidity Widths decrease with vS
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Systematics of thermal fits
y0
4p yields with one ?b and T but different vS
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Chemical analysis vs. rapidity
The system may have fewer degrees of freedom at
high rapidity
1 ? contour
4p result
Assume that at each rapidity we have zero net
strangeness. Fit data to Becattini model .
J.I Jørdre,  Poster Strange 15
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(No Transcript)
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?bar/?, ?bar/? ratios vs pbar/p
rratio
NA57
sSTAR
J. Speltz Thursday
pbar/p
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But what about limiting fragmentation?
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We see a similar effect for kaons
Kinematic limit means production does not go all
the way to beam rapidity
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We see a similar effect for kaons
Kinematic limit means production does not go all
the way to beam rapidity
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Protons dont follow limiting fragmentation
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What about small system?

• PP provides a baseline for AuAu
• These collisions allow us to test canonical
  versus grand-canonical ensemble
• Very little pp data exists at forward rapidities.

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Particle ratios in pp vs. AuAu
B. H. Samset Poster Spec. 34
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pp? AuAu
To describe pp we probably need a micro-canonical
ensemble.
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Conclusions Questions

• Thermal descriptions are a powerful way to
  describe AuAu collisions.
• It is conceivable that there are different
  sources at different rapidities.
• However limiting fragmentation may mean this is
  nonsense.
• By varying vS , y and A we may disentangle the
  effects of baryon density and fragmentation.
• K/? vs ?b coming soon.