Transcript Particel Spectra at AGS, SPS and RHIC

Particle Spectra at AGS, SPS
and RHIC
Dieter Röhrich
Fysisk institutt, Universitetet i Bergen
•
•
Similarities and differences
Rapidity distributions
–
–
•
•
net protons
produced particles
Transverse mass spectra
Hydrodynamics
Proton rapidity distribution
• AGS energies –
centrality dependence
B. Back et al., E917 Collaboration. Phys. Rev. Lett. 86 (2001) 1970
Proton rapidity distribution
• AGS energies, central collisions
- energy dependence
B. Back et al., E917 Collaboration. Phys. Rev. Lett. 86 (2001) 1970
Stopping
• Rapidity shift - energy dependence
F. Videbæk, nucl-ex/0106017
Net proton rapidity distribution
– centrality dependence
• SPS, 158 GeV/nucl., NA49
• RHIC, sNN= 130 GeV, STAR, BRAHMS
N. Xu,
QM2001
Proton and antiproton rapidity
distributions
• SPS, 158 GeV/nucl., NA49
Antiproton/proton ratio –
rapidity distribution
• SPS, 158 GeV/nucl., NA49
• RHIC, sNN= 130 GeV, BRAHMS
Antiproton/proton ratio –
centrality dependence
• SPS, 158 GeV/nucl., NA49
• RHIC, sNN= 130 GeV, BRAHMS
Rapidity distributions
• AGS, 10.8 AGeV
N. Herrmann, J. P. Wessels and T. Wienold,
Ann. Rev. Nucl. Part. Sci. 49 (1999) 581, and references therein
+ = K+ broader than Kp
Pion rapidity distribution
• Comparison + and – SPS, central Pb+Pb, 158 GeV/nucl.
NA49
Same widths for + and -
Kaon rapidity distribution
• Comparison K+ and K– SPS, central Pb+Pb, 40 GeV/nucl.
NA49
Different widths for K+ and K-
-rapidity distribution
• Comparison + and – SPS, central Pb+Pb, 158 GeV/nucl.
NA49
A. Billmeier, PhD thesis, 2001;
R. Barton, J. Phys. G27 (2001) 367
-
+
Different widths for  + and -
Rapidity distributions
• Suddenly hadronizing QGP-fireball
+ remaining internal longitudinal flow of
colliding quarks
J. Letessier, J. Rafelski, hep-ph/0106151
SPS
NA49
 = 1.22
K+ = 1.25
(K- = 1.17)
Transverse momentum spectra
• Inv. CS 
X.-N. Wang, QM01
Hard component:
next session
Soft component:
• Transverse mass spectra
1/mT dN/dmT (a.u.)
fit function:
1/mTdN/dmT ~ exp(-mT/T)
mT  m
fit range:
: pT ~ .3 – 1 GeV/c
heavier hadrons:
pT  1.5–2 GeV/c
Transverse mass spectra
• Comparison K+ and K– SPS, NA44
Histograms: RQMD; fit: 1/mTdN/dmT ~ exp(-mT/T)
Transverse mass spectra
• Comparison + and – SPS, Pb+Pb, 158 GeV/nucl.,
different centralities
WA97
• Central Pb+Pb collisions, inverse slopes:
 = 305 ± 25 MeV, + = 287 ± 30 MeV;
• Similar spectra for particle/antiparticle
Transverse mass spectra
• Comparison  and 
RHIC, central Au+Au (14%)
STAR
No feed-down correction
e(-mt/T)
 (x2)

T=352+-7 MeV
• Identical slope parameters
• Indication of deviations from single slope
fit at low and high mT
Centrality dependence of
transverse mass spectra (1)
• SPS,
158 GeV/nucl.,
WA97: W+ W+
No dependence
• RHIC,
STAR:
 K-K+
No dependence
STAR, submitted to Phys. Rev. Lett.
Centrality dependence of
transverse mass spectra (2)
J.W. Harris, QM01
• RHIC, Au+Au
STAR: K-
Slight dependence
• RHIC, Au+Au
STAR: p
Strong dependence
J.W. Harris, QM01
Inverse slope parameter –
p+p vs Pb+Pb
NA49;
A.M. Rossi, Nucl. Phys. B84 (1975) 269
• SPS,
p+p
• SPS,
central
Pb+Pb
Inverse slope parameter vs
particle mass (1)
• RHIC, central Au+Au
STAR data: C. Roy, this conference

K
p 
W
Inverse slope parameter vs
particle mass (2)
• Comparison RHIC (central Au+Au)
and SPS (central Pb+Pb)
STAR data: C. Roy, this conference

K
p 
Wd
J/
Inverse slope parameter
vs sqrt(s)
•
  K-K+
NA49, STAR
Central Au+Au(Pb+Pb)
p+p
Nucl.Phys. A661(1999)506
Phys.Rev.Lett B491(2000)59
Nucl.Phys. B203(1982)27
Sudden breakup of QGP-fireball
• Thermal freeze-out conditions
= chemical freeze-out
SPS, central Pb+Pb, WA97 data
J. Rafelski, G. Torrieri, J. Letessier, hep-ph/0104132
Tfo,global  145 MeV
v  0.52c
Hydrodynamics
motivated mT fit (1)
• SPS, central Pb+Pb;
H. Appelshaeuser (NA49), Eur. Phys. J. C2 (1998) 661;
B. Tomasik, U. Wiedemann, U.W. Heinz, nucl th/9907096
• Correlate - transverse mass spectrum and -- BoseEinstein correlations
• 2 contour plots for the fits of the single particle mTspectrum and of the Cartesian HBT radii
Tfo  100 MeV
<v>  0.55c
Hydrodynamics
motivated mT fit (2)
• RHIC, central Au+Au;
STAR
S. Margetis, ThermalFest, 2001;
P. Jones, this conference
Shape of the mT spectrum depends on particle mass, mTrange, flow profile:
R
dn
m cosh    pT sinh  
  r dr mT K1  T
I

 0

mT dmT 0
T
T
STAR Preliminary
solid : used in fit
and
r (r)  s f (r)
flow profile used:
-
1/mT dN/dmT (a.u.)
1
where   tanh r
r =s (r/R)0.5
K-
s
p
R

mT - m0
[GeV/c2]
E.Schnedermann et al,
PRC48 (1993) 2462
Hydrodynamics
motivated mT fit (3)
• RHIC, central Au+Au;
STAR
S. Margetis, ThermalFest, 2001;
P. Jones, this conference
2 map (contour plot for
95.5%CL)

Tth = 0.13 [GeV]
<r > = 0.52 [c]
p
K-
Tth [GeV]
At chi square minimum
-
0
0.4
<r > [c]
0
0.4
 Strong radial flow at RHIC
ßr (RHIC) = 0.52c
Tfo (RHIC) = 0.13 GeV
Hydrodynamics
motivated mT fit (4)
• RHIC, central Au+Au, -K-p;
PHENIX
J. Buward-Hoy, ThermalFest, 2001
1/mt dN/dmt = A  f()  d mT K1( mT /Tfo cosh  ) I0( pT /Tfo sinh  )
PHENIX Preliminary
where   radius r = r/R,
particle density distribution:
f()
1

linear velocity profile:
t()

Tfo ~ 125 - 83 MeV ~ 104 MeV
t ~ 0.6 - 0.8 ~ 0.7
< t> ~ 0.4 - 0.6 ~ 0.5
Hydro + Cascade model
• SPS, RHIC, central Pb+Pb (Au+Au)
D. Teaney, J. Lauret, E.V. Shuryak, nucl-th/0104041
• RHIC, central Au+Au;
PHENIX
J. Buward-Hoy, ThermalFest, 2001
• , K
• Tfo ~ 135 MeV
• <t > ~ 0.55
• nucleons
• Tfo ~ 120 MeV
• <t > ~ 0.6
Summary
• Variety of shapes of rapidity
distributions
• Complex transverse mass
spectra
• Hydrodynamics
– Strong radial flow
• t  0.5-0.7c
– Sudden QGP break up model:
• Tglobal  145 MeV (SPS)
– Hydro mT-fits:
• Tfo, thermal  100-130 MeV