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Strangeness Production in Heavy Ion Collisions at SPS Energies

Strangeness Production in Heavy Ion Collisions at SPS Energies. Andr é Mischke for the NA49 Collaboration. a.mischke@phys.uu.nl. Outline. Physics Programme Experimental Setup Particle Identification / V0-Reconstruction Spectra on Kaons,  and  Energy Dependence Baryon Ratios

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Strangeness Production in Heavy Ion Collisions at SPS Energies

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  1. Strangeness Productionin Heavy Ion Collisions at SPS Energies André Mischke for the NA49 Collaboration a.mischke@phys.uu.nl Andre Mischke

  2. Outline • Physics Programme • Experimental Setup • Particle Identification / V0-Reconstruction • Spectra on Kaons,  and  • Energy Dependence • Baryon Ratios • Summary Andre Mischke

  3. Physics Programme in NA49 • Search for the onset of deconfinement • Energy scan programme at CERN-SPS (started in ‘99) • - central Pb-Pb events at 20, 30, 40, 80 and 158 AGeV • Search for anomalies in the energy dependence • of physical observables; here strangeness production • - s quarks are mainly carried by the  • - essentially half of thes quarks are contained in K+ Andre Mischke

  4. Event display: ~1200 charged particles NA49 Detector at CERN-SPS • 2 super-conducting dipole magnets, • 9 Tm bending power • 4 volume TPC’s for tracking and • PID via dE/dx • 2 ToF walls for PID at mid-rapidity • 180,000 channels • Event rate ~7 Hz • Fixed target experiment • Large acceptance hadron • spectrometer NIM A430, 210 (1999) Andre Mischke

  5. Identification of Charged Particles • Specific energy loss dE/dx: • cover forward rapidity • (p > 7 GeV/c) • dE/dx resolution ~ 4% • Time-of-Flight: • at mid-rapidity • resolution ~ 60ps Andre Mischke

  6. V0 - Reconstruction Neutral strange particles are identified by their decay topology:   p + - (64.1 %) For the spectra:  contain 0 158 AGeV Invariant mass spectra - measured mass in agreement with PDG - mass resolution  2 MeV/c2 Andre Mischke

  7. Kaons: Transverse Spectra at mid-rapidity Slopes are similar for K+ and K- Andre Mischke

  8. preliminary shown on SQM2003 published: PRC 66, 054902 (2002) Kaons: Rapidity Distributions K+ broader than K- Andre Mischke

  9. Energy Dependence of K/ ratio published RHIC Pronounced maximum Kink-like structure Andre Mischke

  10. : Transverse Spectra at mid-rapidity Slope parameter slightly increases with increasing energy Andre Mischke

  11. : Rapidity Distributions •  broader than • Flattening of the  rapidity distribution Andre Mischke

  12. Energy Dependence of / ratio nucl-ex/0209002 Non-monotonic energy dependence Continuous rise Andre Mischke

  13. Strangeness Enhancement in  Production N  K dominant process hep-ph/0209284 • Same behaviour for the K+/+ ratio • Strangeness enhancement not a unique • signature for QGP formation Andre Mischke

  14.  (ss)  K+K- Spectra on  Slope increases with energy Andre Mischke

  15. 40 AGeV 80 AGeV 158 AGeV : Energy Dependence PLB 491, 59 (2000) NA49 Preliminary / increases monotonically Andre Mischke

  16. 40 AGeV • First measurements of • rapidity distribution in Pb-Pb at 158 AGeV! (presented on QM2002) Multi-strange Baryons Andre Mischke

  17. Effect of Baryon Density • Strong increase with energy • due to decreasing baryon density • Particle ratios increase with the number • of valence s/sbar quarks in the baryon Andre Mischke

  18. Summary • Large data sets available for the SPS energy range from 20 to 158 GeV per nucleon • Excitation function of K and  production in HIC: - Pronounced maximum in the K+/+ ratio around 30 AGeV - / ratio shows a maximum at the same energy • / ratio increases monotonically with cms energy • First results on multi-strange hyperons at lower SPS energies Andre Mischke

  19. Collaboration 20 Institutes from 12 nations 96 participants T. Anticic, B. Baatar, D. Barna, J. Bartke, M. Behler, L. Betev, H. Bialkowska, A. Billmeier, C. Blume, B. Boimska, M. Botje, J. Bracinik, F.P. Brady, R. Bramm, R. Brun, P. Buncic, V. Cerny, P. Christakoglou, J.G. Cramer, P. Csato, P. Dinkelacker, V. Eckardt, F. Eckhardt, P. Filip, H.G. Fischer, Z. Fodor, P. Foka, P. Freund, V. Friese, J. Gal, M. Gaździcki, G. Georgopoulos, E. Gladysz, S. Hegyi, C. Höhne, K. Kadija, A. Karev, V.I. Kolesnikov, T. Kollegger, R. Korus, M. Kowalski, I. Kraus, M. Kreps, M. van Leeuwen, B. Lasiuk, M. van Leeuwen, P. Levai, A.I. Malakhov, C. Markert, B.W. Mayes, G.L. Melkumov, C. Meurer, A. Mischke, M. Mitrovski, J. Molnar, St. Mrowczynski, G. Palla, A.D. Panagiotou, K. Perl, A. Petridis, M. Pikna, L. Pinsky, F. Pühlhofer, J.G. Reid, R. Renfordt, W. Retyk, C. Roland, G. Roland, M. Rybczynski, A. Rybicki, A. Sandoval, H. Sann, N. Schmitz, P. Seyboth, F. Sikler, B. Sitar, E. Skrzypcak, G. Stefanek, R. Stock, H. Ströbele, T. Susa, I. Szentpetery, J. Sziklai, T.A. Trainor, D. Varga, M. Vassiliou, G.I. Veres, G. Vesztergombi, D. Vranic , S. Wenig, A. Wetzler, Z. Wlodarczyk, I.K. Yoo, J. Zaranek, J. Zimanyi Andre Mischke

  20. Add. Slide(s) Andre Mischke

  21. Energy Dependence of Pion Production Andre Mischke

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