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Kaon and Proton Ratios from Central Pb+Pb Collisions at the CERN SPS

Kaon and Proton Ratios from Central Pb+Pb Collisions at the CERN SPS. Masashi Kaneta for the NA44 collaboration Department of Physics, Hiroshima University. e-mail: kaneta@hiroh2.hepl.hiroshima-u.ac.jp. Introduction m T distributions of K and p from Pb+Pb Particle ratios Summary.

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Kaon and Proton Ratios from Central Pb+Pb Collisions at the CERN SPS

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  1. Kaon and Proton Ratios from Central Pb+Pb Collisions at the CERN SPS Masashi Kaneta for the NA44 collaboration Department of Physics, Hiroshima University e-mail: kaneta@hiroh2.hepl.hiroshima-u.ac.jp Introduction mT distributions of K and p from Pb+Pb Particle ratios Summary

  2. Introduction High energy heavy ion collision Ex p a n s i o n Lots of hadrons are newly created Huge number of collisions Thermal freeze-out Tfo：～140MeV at SPS and AGS energies To describe the system Thermo-chemical model  Masashi Kaneta / Hiroshima univ.

  3. The NA44 Collaboration I.G.Bearden1, H.Bøggild1, J.Boissevain2, J.Dodd3, B.Erazmus4, S.Esumi5,a, C.W.Fabjan6, D.Ferenc7, D.E.Fields2, A.Franz6,b, J.J.Gaardhøje1, M.Hamelin10, A.G.Hansen1, O.Hansen1, D.Hardtke8, H. van Hecke2, E.B.Holzer6, T.Humanic8, P.Hummel9, B.V.Jacak2,c, R.Jayanti8, K.Kaimi5, M.Kaneta5, M.Kopytine2,c, M.Leltchouk3, A.Ljubicic Jr.7, B.Lörstad10, N.Maeda5,d, R.Malina6 M.Murray10, H.Ohnishi5, G.Paic4,6, S.U.Pandey8,e, F.Piuz6, J.Pluta4, V.Polychronakos11, M.Potekhin3, G.Poulard6, D.Reichhold8, A.Sakaguchi5,f, J.Simon-Gillo2, J.Schmidt-Sørensen9, W.Sondheim2, M.Spegel8, T.Sugitate5, J.P.Sullivan2, Y.Sumi5, W.J.Willis3, K.L.Wolf10, N.Xu2,g and D. S. Zachary8 1 Niels Bohr Institute, DK-2100 Copenhagen, Denmark. 2 Los Alamos National Laboratory, Los Alamos, NM 87545 USA. 3 Department of Physics, Columbia University, New York, NY 10027, USA. 4 Nuclear Physics Laboratory of Nantes, 44072 Nantes, France. 5 Hiroshima University, Higashi-Hiroshima 739, Japan. 6 CERN, CH-1211 Geneva 23, Switzerland. 7 Rudjer Boskovic Institute, Zagreb, Croatia. 8 Department of Physics, Ohio State University, Columbus, OH 43210, USA. 9 Department of Physics, University of Lund, S-22362 Lund, Sweden. 10 Texas A&M University, College Station, TX 77843, USA. 11 Brookhaven National Laboratory, Upton, NY 11973, USA. a b c d e f g Now at Universität Heidelberg, Physikalisches Institut, 69120 Heidelberg, Germany. Now at Brookhaven National Laboratory, Upton, NY 11973, USA. Now at State University of New York, Stony Brook, NY 11794, USA. Now at Department of Physics, Florida State University, Tallahassee, FL 32306-3016, USA. Now at Wayne State University, Detroit, MI 48202, USA. Now at Department of Physics, Osaka University, Toyonaka, Osaka 560, Japan. Now at Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Masashi Kaneta / Hiroshima univ.

  4. Masashi Kaneta / Hiroshima univ.

  5. PID Masashi Kaneta / Hiroshima univ.

  6. Acceptance Masashi Kaneta / Hiroshima univ.

  7. Selection of centrality Masashi Kaneta / Hiroshima univ.

  8. K-/K+ and p/p ratio as a function of PT and centrality Masashi Kaneta / Hiroshima univ.

  9. mT distribution centrality : top 8.5% Inverse slope [MeV] dN/dy K+ K- p p 237±3 21.3±0.8 238±3 11.5±0.4 303±6 25.3±1.0 281±8 1.64±0.09 systematic error: <4% for inverse slope <10% for dN/dy Masashi Kaneta / Hiroshima univ.

  10. Effect for proton yield from weak decays • Effectsof L and S+ decay to proton spectra are estimated by a Monte-Carlo simulation (Also, antiparticle to antiproton) • dN/dy and mT slope are referred from RQMD(V1.08) and experimental data (NA49 coll., Nucl. Phys. A610 (1996) 188c) Inverse slope [MeV] dN/dy p p 331±10±1120.1±1.2±1.3 316±13±151.11±0.19±0.11 The error by correction reflected the result of increasing and decreasing the (L+S+)/p ratio by a factor of 1.5 Masashi Kaneta / Hiroshima univ.

  11. Strange neutral hadron gas model gs=1 ms is given as a function of Tch and mq for different gs by numerical calculation. Tch, mq : 5MeV step gs : 0.05 step Masashi Kaneta / Hiroshima univ.

  12. Tch mq ms gs = 155～170 MeV = 75～ 85 MeV = 22～ 31 MeV = 0.75～0.95 Extract chemical freeze-out temperature and chemical potentials comparison of ratios from experiment with ratios from model Masashi Kaneta / Hiroshima univ.

  13. Comparison of Tch,mq,ms from Pb+Pb with those from other systems The Tch and mq in Pb+Pb are close to the values in S+A at SPS energies at AGS energies Tch： mq ： ms : 155～200MeV 120～140MeV 60～120MeV 160～200MeV 3～ 40MeV 60～120MeV Masashi Kaneta / Hiroshima univ.

  14. Summary Chemical freeze-out temperature and chemical potentials are extracted from kaon and proton ratio in Pb+Pb collisions Tch mq ms gs = 155～170 MeV = 75～ 85 MeV = 22～ 31 MeV = 0.75～0.95 • At SPS energies, • Chemical freeze-out temperature Tch • > Tfo(～140MeV) It is quite natural with view point of thermodynamics • Collisions system dependence of Tch ,mq andms is less clear than dependence Masashi Kaneta / Hiroshima univ.

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