1. Observation of the Onset of Deconfinement at SPS / CERN
In-Kwon YOO
Nuclear Research Institute
Pusan National University
Busan, Republic of KOREA

2. HIM (Heavy Ion Meeting) 2004
Outline
Physics Motivation
Experimental Survey
Physics Results and Interpretations
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

3. HIM (Heavy Ion Meeting) 2004
Motivation
Looking for the QGP
Experiment
Anomalies at the Phase Transition ?
Results
Hadronic Observables
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004
Collision Energy

4. HIM (Heavy Ion Meeting) 2004
Motivation
Experiment
Energy Scan :
20, 30, 40, 80, 158 AGeV
System Scan :
pp, C+C, Si+Si, Pb+Pb
Results
NA 49
Elementary Reactions :
p+p, p+p, d+p, p+A
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

5. HIM (Heavy Ion Meeting) 2004
Motivation
NA49 Detector System
Experiment 1m
Results
NIM A430 (1999)
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

6. HIM (Heavy Ion Meeting) 2004
Motivation
TPC Tracks (topview)
Experiment
Results
Primary Vertex vs. Secondary Vertex
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

7. HIM (Heavy Ion Meeting) 2004
Motivation
TOF Hits
Experiment
Results
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

8. Particle Identifications
Motivation
Particle Identifications
Track Curvature
Momentum
Experiment
Specific dE/dx
Bethe-Bloch
dE/dx PID
Results
Time-Of-Flight & Tracklength
TPC-> tracking & dEdx
KAON !
Velocity
Outlook
Mass
TOF PID
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

9. Resonance Reconstruction
Motivation
Resonance Reconstruction
minv = [(E1+E2)2-(p1+p2)2]1/2
Experiment
Identify secondary vertices
Examples in
Results
Lambda Lifetime .. !
Background
WHAT DO WE HAVE NOW ?
Pion, Kaon, proton, Lambda, Omega, Phi,..
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

10. mT Spectra [d2N/(mT dydmT) ~ exp(mT/T)]
Motivation
mT Spectra [d2N/(mT dydmT) ~ exp(mT/T)]
20GeV
30GeV
Experiment
40GeV
Results
Slope Parameter Temperatur
158GeV
80GeV
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

11. Rapidity Distribution
Motivation
Rapidity Distribution
Experiment
Almost Full Aceptance in forward hemisphere
Results
Open circle, filled circle
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

12. Results Interpretation
Motivation
Results Interpretation
Energy Dependence (AGS – SPS – RHIC)
Transverse Mass Spectrum  Temperature
Rapidity Distribution  Multiplicity
Strangeness Production
System Size Dependence (p+p, C+C, Si+Si, Pb+Pb)
Hadron Multiplicity
E-by-E Fluctuations
Outlook of NA49
Experiment
Results
Slope Parameter Temperatur
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

13. Signals of Deconfinement ?
Motivation
Signals of Deconfinement ?
PION KINK
THE STRANGE HORN
THE STEP IN SLOPES
Experiment
Results
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

14. HIM (Heavy Ion Meeting) 2004
Motivation
PION KINK
Experiment
Results
Open circle, filled circle
Outlook
Onset at Elab = AGeV
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

15. The Pion Kink M.Gazdzicki, Z.Phys. C66 (1995) 659
Motivation
Experiment
Results
Outlook
The Pion Kink M.Gazdzicki, Z.Phys. C66 (1995) 659
Deconfinement
The early stage of the collisions : Fireball
An Increase of Entropy, due to high number of effective degree of freedom in QGP
E ~ s1/2 ; V ~ s-1/2
e = E/V ~ s ; e ~ gT4
T ~ g-1/4 s1/4
<p> ~ S ~ gVT3 ~ g1/4s1/4 = g1/4F
<p> ~ Entropy
An Increase of Pion Yield at the Onset of Deconfinement
Slope Parameter Temperatur
<p> ~ g1/4 F
Statistical Model of the Early Stage (SMES) :
M. Gorenstein, Acta Phys. Polon. B30 (1999) 2705
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

16. HIM (Heavy Ion Meeting) 2004
Motivation
Experiment
Results
Outlook
The Statistical Model of the Early Stage (SMS) M.Gorenstein, Acta Phys. Polon. B30 (1999) 2705
gH for hadron gas
1.3
gH < gQ
gQ for QGP
gQ / gH ~ (1.3) 4 ~ 3
Slope Parameter Temperatur
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

17. Strangeness Enhancement with the strange horn
Motivation
Experiment
Results
Outlook
Strangeness Enhancement with the strange horn
Strangeness Enhancement :
J. Rafelski, Phys. Rep. 88, 331 (1982)
Strange Horn :
M.Gazdzicki, D.Roehrich, Z.Phys. C71 (1996) 55
M.Gorenstein, Acta Phys. Polon. B30, 2705
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

18. Strange/Nonstrange Ratio
Motivation
Experiment
Results
Outlook
Strange/Nonstrange Ratio
<K+K’>/<p>
Hadron Gas (K+K’)/p at T ~ TC
<K+K’> ~ T3/2exp(-mK/T)
<p> ~ T3
<s+s’>/<ns>
QGP at T > TC (ms < T)
<s+s’> ~ T3 TC T
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

19. HIM (Heavy Ion Meeting) 2004
Motivation
Slope vs. Energy
Experiment
Results
Slope Parameter Temperatur
Outlook
The Step at Elab =20 – 30 AGeV!
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

20. Onset of Deconfinement ? !
Motivation
Onset of Deconfinement ? !
Several anomalies in hadron production are observed at the low SPS energies
The onset of the observed anomalies is located at about 30 AGeV
The anomalies cannot be reproduced by the models without phase transition
Measured rapid changes are consistent with the model assuming 1st order PT
Experiment
Results
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

21. System Size dependence of Fluc.
Motivation
System Size dependence of Fluc.
@158 AGeV
Experiment
E-by-E Multiplicity Fluctuation
Results
E-by-E pT Fluctuation
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

22. System Size dependence @158 AGeV
Motivation
System Size AGeV
Role of Volume in Strong interaction
Experiment
Results
Anomalies at NW ≈ 70
Is the maximum in fluctuations observed for small systems related to PT ?
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

23. HIM (Heavy Ion Meeting) 2004
Motivation
Summary and Outlook
Experiment
Results
Outlook
(Collision Energy) – (System Size) scan ≈ T-m scan
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

24. Light ION program at the SPS
Motivation
Light ION program at the SPS
Experiment
Results
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

25. Possible future experimental landscape
Motivation
Possible future experimental landscape
Experiment
Results
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

26. HIM (Heavy Ion Meeting) 2004
Motivation
Experiment
Results
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

27. Light ION program at the SPS
Motivation
Light ION program at the SPS
Experiment
Results
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004

28. HIM (Heavy Ion Meeting) 2004
Motivation
NA49 Collaboration
Experiment
Results
Outlook
In-Kwon YOO
HIM (Heavy Ion Meeting) 2004