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Chemical and thermal freeze-out parameter from 1A to 200A GeV

Chemical and thermal freeze-out parameter from 1A to 200A GeV. Phys. Rev. C 60 054908 J. Cleymans and K. Redlich 8/Feb/2000 H.I. Colloquium Masashi Kaneta. Introduction. m B ch , T ch for 1A to 200A GeV (GSI-SIS, BNL-AGS, CERN-SPS)

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Chemical and thermal freeze-out parameter from 1A to 200A GeV

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  1. Chemical and thermal freeze-out parameter from 1A to 200A GeV Phys. Rev. C60 054908 J. Cleymans and K. Redlich 8/Feb/2000 H.I. Colloquium Masashi Kaneta Masashi Kaneta

  2. Introduction • mBch, Tch for 1A to 200A GeV (GSI-SIS, BNL-AGS, CERN-SPS) • Under Tch, no inelastic collisions among hadrons and unchanged hadron yield • From SIS-SPS results, possibility of extrapolation of mBch, Tch for higher beam energy Masashi Kaneta

  3. Contents • Sec. II • Flow effect to hadron ratio? • Sec. III • Strangeness conservation • Sec. IV • <E>/<N>=1GeV for all collisions system • e = 45 MeV/fm3 or n = 0.05/fm3 at thermal freeze-out • Sec. V and VI • Discussion and Summary Masashi Kaneta

  4. Sec. II Flow effect to hadron ratio? • No, if we use particle yields in all phase space • Confirmed in case of • Cooper Frye formula • Cylindrical flow formula • Superposition of fire balls Masashi Kaneta

  5. Sec. III Strangeness conservation • Consider strangeness neutrality in 4p • Ignore contribution of X and W for strangeness quantum number • No strangeness saturation factor in this model Masashi Kaneta

  6. Sec. IV Chemical and Thermal freeze-out • Chemical Freeze-out • Common chemical freeze-out at <E>/<N>  1 GeV • <E>/<N>  MN + 3/2 Tch at low Tch • <E>/<N>  <M> + 3/2 Tch at high Tch Masashi Kaneta

  7. Sec.IV (continued) • Thermal Freeze-out • Chemical freeze-out to Thermal freeze-out • Assuming S/B = constant • Tth given from flow analysis • e =45 MeV/fm3 or n =0.05 /fm3 Masashi Kaneta

  8. Sec.V Discussion Tch = 140 MeV mB = 380 MeV • Energy dependence of chemical freeze-out parameters • <p>/Aparticipant = c(s1/2 - sth1/2) ; sth1/2=2mN+mp 40 A GeV Pb+Pb  s1/2 8.9  R=2.32 Masashi Kaneta

  9. Sec.V (continued) NA44 Pb+Pb • Tch (mB) increases (decreases) with beam energy • Hadronic ratios • K+/p +ratios are on the line of <E>/<N> = 1GeV until AGS energy • At SPS energy region, K+/p +ratios below the prediction • An effect of QGP? (Ref.[49-51]) Masashi Kaneta

  10. Sec.V (continued) • K+/K- ratios by this model agree experimental data • gs effect for K+/K- ratio is negligible, therefore this model can predict it well • Prediction of hadron ratios in 40 AGeV Pb+Pb • Tch = 140 MeV, mB = 380 MeV • anti-Baryon to Baryon ratio is smaller than in158 A GeV due to higher baryon density Masashi Kaneta

  11. Summary • In 1A - 200A GeV • chemical freeze-out happens around <E>/<N> = 1GeV • Predictions of hadron ratios in 40 A GeV is highly reliable • Thermal freeze-out happens • e =45 MeV/fm3 or n =0.05 /fm3 Masashi Kaneta

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