Observation of the Onset of Deconfinement at SPS / CERN In-Kwon YOO (yoo@pusan.ac.kr) Nuclear Research Institute Pusan National University Busan, Republic of KOREA

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

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

HIM (Heavy Ion Meeting) 2004 Motivation NA49@SuperProtonSynchrotron.CERN http://na49info.cern.ch 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

HIM (Heavy Ion Meeting) 2004 Motivation NA49 Detector System Experiment 1m Results NIM A430 (1999) 210-244 Outlook In-Kwon YOO HIM (Heavy Ion Meeting) 2004

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

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

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

Resonance Reconstruction Motivation Resonance Reconstruction minv = [(E1+E2)2-(p1+p2)2]1/2 Experiment Identify secondary vertices Examples in Pb+Pb@158AGeV Results Lambda Lifetime .. ! Background WHAT DO WE HAVE NOW ? Pion, Kaon, proton, Lambda, Omega, Phi,.. Outlook In-Kwon YOO HIM (Heavy Ion Meeting) 2004

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

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

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

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

HIM (Heavy Ion Meeting) 2004 Motivation PION KINK Experiment Results Open circle, filled circle Outlook Onset at Elab = 20-30 AGeV In-Kwon YOO HIM (Heavy Ion Meeting) 2004

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

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

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

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

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

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

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

System Size dependence @158 AGeV Motivation System Size dependence @158 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

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

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

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

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

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

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