P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Results from NA49 at the CERN SPS
• NA49 experiment• Recent results on inclusive production
– Baryon stopping (E.Kornas, C.Blume)– He3, tritium production (V.Kolesnikov)
– Intermediate pT results (A.Laszlo, T.Schuster)
– Elliptic flow (G.Stefanek)
• Status of fluctuation measurements (K.Grebieszkow, M.Rybczynski, B.Lungwitz, C.+G.Roland)
• Future plans
P.Seyboth, Max-Planck-Institut für Physik, Munich for the NA49 collaboration
Results on pion source imaging → talk by R.Lacey
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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C. Alt, T. Anticic, B. Baatar, D. Barna, J. Bartke, L. Betev, H. Białkowska, C. Blume, B. Boimska, M. Botje, J. Bracinik, R. Bramm, P. Bunčić, V. Cerny,
P. Christakoglou, P. Chung, O. Chvala, J.G. Cramer, P. Csató, P. Dinkelaker, V. Eckhardt, D. Flierl, Z. Fodor, P. Foka, V. Friese, J. Gál, M. Gaździcki, V. Genchev, G. Georgopoulos, E. Gładysz, K. Grebieszkow, S. Hegyi,
C. Höhne, K. Kadija, A. Karev, D. Kikola, M. Kliemant, S. Kniege, V.I. Kolesnikov, E. Kornas, R. Korus, M. Kowalski, I. Kraus, M. Kreps, A. Laszlo, R. Lacey, M. van Leeuwen, P. Lévai, L. Litov, B. Lungwitz, M. Makariev, A.I. Malakhov, M. Mateev, G.L. Melkumov, A. Mischke,
M. Mitrovski, J. Molnár, S. Mrówczyński, V. Nicolic, G. Pálla, A.D. Panagiotou, D. Panayotov, A. Petridis, W. Peryt, M. Pikna, J. Pluta, D. Prindle, F. Pühlhofer, R. Renfordt, C. Roland, G. Roland, M. Rybczyński, A. Rybicki, A. Sandoval,
N. Schmitz, T. Schuster, P. Seyboth, F. Siklér, B. Sitar, E. Skrzypczak, M. Slodkowski, G. Stefanek, R. Stock, C. Strabel, H. Ströbele, T. Susa,
I. Szentpétery, J. Sziklai, M. Szuba, P. Szymanski, V. Trubnikov, D. Varga, M. Vassiliou, G.I. Veres, G. Vesztergombi, D. Vranić, A. Wetzler,
Z. Włodarczyk, A. Wojtaszek, I.K. Yoo, and J. Zimányi
The NA49 Collaboration
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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The NA49 Detector
Target: Pb foil, 20cm liquid H2 VCAL detects projectile spectatorsΔp/p2 = 7 (0.3) • 10-4 (GeV/c)-1 (VTPC-1, VTPC+MTPC)Particle identification: dE/dx (3 – 6 %), TOF (~ 60 ps) decay topology (K0, Λ, Ξ, Ω)
p > 7 GeV/cdE/dx
forward rapidity
2.5 < p < 10 GeV/c TOF + dE/dxat midrapidity
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Baryon stopping (1) Proton and antiproton rapidity spectra in central Pb+Pb collisions
• new results from dE/dx analysis at forward rapidities• published results from TOF analysis at midrapidity (PRC73(2006)044910)
NA49 preliminary NA49 preliminary
pp
evolution of shape, decrease of yield Gaussian shape, increase of yield
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Baryon stopping (2)
net-baryon distributions in central 7% Pb+Pb collisions
construction of net-baryon distributions:
scaling factors taken from statistical model fits F.Becattini et al., PRC73 (2006) 044905
0( ) ( ) ( ) ( )nN B B S p p S S
NA49 preliminary
20A GeV 30A GeV 40A GeV 80A GeV
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Baryon stopping (3)
NA49 preliminary
evolution of net-baryon rapidity distributions
• pronounced change of shape at SPS energies peak -> dip structure
• net-baryon density decreases rapidly at mid-rapidity
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Baryon stopping (4)
energy dependence of projectile rapidity loss <δy>/yp
Central Pb+Pb/Au+Au
preliminary
p
p
yB-B
p 0part
y = y - <y>
dN2 = y - y dy
N dy
• at AGS, SPS constant ≈ 0.6 decrease at RHIC energies• reproduced by UrQMD <xF>≈ 0.38
(UrQMD: M.Bleicher, Florence Workshop)
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Baryon stopping (5)
BBNN
inel Es
E 2
energy dependence of inelasticity K
Inelasticity:
pNN
inel
ms
EK
2
2
central A+A collisions
NA49 preliminary
Total inel. energy per net-baryon:
1cosh ( )
p
p
yB B
TB B yyB B
dNE m y dy
N dy
Energy of single net-baryon:
Inelasticity saturates at K = 0.7-0.8 above SPS
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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light fragments (1)
3He
td
3He identification: dE/dx + TOF
NA49 preliminary
t
Central Pb+Pb|y | < 1.0
NA49 preliminary3He
Central Pb+Pb
|y | < 1.0
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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light fragments (2)
1const~ A-pdy
Adn
coalescence paramater
from p spectra:
NA49 preliminary
penalty factor
agrees with statistical hadron gas prediction
mid-rapidity yields
p d He3
33
3 3 ,
A
pAA A p A p
A p
d Nd NE B E P A P
dP dP
gradual decrease with energy
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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light fragments (3)
NA49 preliminary
3HeCentral Pb+Pb
total yields estimated from parabolic fits up to |ybeam| (motivated by RQMD)
3HeCentral Pb+Pb
4 yields
NA49 preliminary
yields show surprising agreement with statistical hadron gas model
F.Becattini et al., PRC73 (2006) 044905
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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light fragments (4)
coalescence model blast wave model
20A GeV
NA49 preliminary
Central Pb+Pb|y | < 1.0
larger T, smaller <βT> required for d,3He
constant density, v(r) = vf (r/Rf)α
→ <mT> - m ~ A1-α (A.Pollieri et al., PLB419 (1998) 19)
linear velocity increase ok
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Intermediate pT results (1)
baryon/meson ratio
• deviates from blast-wave (hydro) for pT > 1.2 GeV/c as at RHIC
• SPS data reach coalescence range but end below pQCD region
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Intermediate pT results (2)
Baryon/meson ratio at SPS vs RHIC
SPS: central Pb+Pb at √s= 17.3 GeVRHIC: central Au+Au at √s= 200 GeV • same relative increase with pT
at SPS and RHIC
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Intermediate pT results (3)
nuclear suppression factor of pions at SPS and RHIC
2
2
coll AA tAA t
pA tcoll
N pA d N dp dyR p
d N dp dyN AA
2
2
1 AB tAB t
pp tcoll
d N dp dyR p
d N dp dyN AB
SPS NA49 preliminary
RHIC Phenix
similar increase of ratio at SPS in pPb and PbPb (Cronin effect)
approaches binary scaling at SPS in accessible pT range
PbPb/pp
NA49 preliminary
pPb/pp
Cronin
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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elliptic flow v2 in Pb+Pb collisions at 158AGeV
• blast wave fits ok• overprediction by pure hydro model• preliminary K0 unexpectedly low
KET = mT – m (A.Adare et al.,nucl-ex/0608033)
• reasonable scaling also at SPS• coalescence region not reached
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Changes of hadron production properties in central Pb+Pb collisions at the CERN SPS energies are not reproduced by models without onset of deconfinement at low SPS energies
str
an
gen
ess/p
ion
slo
pe o
f p
T s
pectr
a
AGS SPS AGS SPS RHIC
1/4NN s
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Freeze-out parameters determined from hadron yields for central Pb+Pb collisions at the CERN SPS are close to
the predicted phase boundary between hadron gas and quark-gluon plasma
A critical point of stronglyinteracting matter is predicted by QCD. It may be discoveredas a maximum of fluctuations in a comprehensive energy
and system size scan at the CERN SPS
and low energy RHIC
baryochemical potential
tem
per
atu
re
hadron gas analysis: F.Becattini et al., PRC73(2006)044905
lattice QCD results: Z.Fodor and S.Katz, JHEP 04(2004)050
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Event-by-event fluctuations of negative hadron multiplicity
• fluctuations measured at forward rapidity (1.1 < yπ < 2.6) where azimuthal acceptance is best
• number of projectile participants fixed by projectile spectator energy cut; no restriction on target participants • central collisions: fluctuations nearly Poissonian (independent emission)
• peripheral collisions: fluctuations exceed Poissonian
Pb+Pb at 158AGeV, 1.1 < yπ < 2.6
measure: ω = Var(n)/<n>
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Event-by-event fluctuations of negative hadron multiplicity
• rise due to effect of fluctuating target participants ?• reproduced by string models with string fusion (QGSM+fusion)
158AGeV
1.1 < yπ < 2.6
• fluctuations in central Pb+Pb small and nearly energy independent• trend in statistical models due to conservation laws
1.1 (1.0) < yπ < 2.6 (ybeam)
NA49 preliminary
centrality energy
L.Cunqueiro et al.,PRC69(2005)024907
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Event-by-event fluctuations of <pT> (negative hadrons)
• distributions of <pT> similar for real and mixed events
• no evidence for distinct event classes
• non-statistical (dynamical) fluctuations are small, < few %
1.1 < yπ < 2.6
22
T
Ni
T T T Ti 1
Zp - <z
z p - <p > Z (p - <p > )
N
measure: ΦpT
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Event-by-event fluctuations of <pT> (negative hadrons)
increase for peripheral collisions effect of string fusion ?
NA49 preliminary
1.1 < yπ < 2.6
STAR158A GeV1.1 < yπ < 2.6
no significant change with energy for central Pb+Pb collisions
1.1 < yπ < 2.6
centrality energy
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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The Event-by-Event K/π ratioB
eam
Ene
rgy
σ2dyn = σ2
data – σ2mixed
maximum likelihood fit for each event
NA49 preliminary
STAR
Fluctuations increase at lower energy effect of onset of deconfinement ?
M.Gorenstein et al.,PLB585(2004)237
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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The Event-by-Event (p + p)/π ratioB
eam
Ene
rgy
The distribution of the E-by-E p/π ratiois narrower for data than mixed events. Effect of baryon resonance decay ?
NA49 preliminary
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Future Plans
Search for the QCD critical point in fluctuations → scan lower SPS energies and smaller size nuclei
Proposal CERN-SPSC-2006-034/P-330: under consideration at SPSC
( upgraded NA49 detector )
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Backup Slides
P.Seyboth: Results from NA49 at the CERN SPS 23rd Winter Worshop on Nuclear Dynamics - Big Sky, February 12-17, 2007
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Pb+Pb collisions at top SPS energy
• Initial energy density exceeds the critical value predicted by lattice QCD ( ≈ 1 GeV / fm3 )
• Strong collective behavior– anisotropic and radial flow– transverse expansion of the matter droplet by factor 2
• Proposed signatures for deconfinement observed – strangeness enhancement– J/Ψ,Ψ’ yield suppression– di-lepton enhancement, ρ0 modification(circumstantial evidence for a new state of matter (2000)
Validate by a search for a threshold in the largest collision system (central Pb+Pb reactions)
SPS energy scan: 20, 30, 40, 80, 158 GeV/nucleon (√sNN = 6.3, 7.6, 8.7, 12.3, 17.3 GeV)