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Charged Hadron Results from 19.6 GeV Au+Au

Charged Hadron Results from 19.6 GeV Au+Au. Daniel Cebra University of California, Davis (for the STAR Collaboration). Triggering for the 19.6 GeV dataset. ZDC Trigger (147953). Counts. CTB Trigger (27513). Nch.

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Charged Hadron Results from 19.6 GeV Au+Au

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  1. Charged Hadron Results from 19.6 GeV Au+Au Daniel Cebra University of California, Davis (for the STAR Collaboration)

  2. Triggering for the 19.6 GeV dataset ZDC Trigger (147953) Counts CTB Trigger (27513) Nch The STAR trigger was not optimized for 19.6 GeV Collisions. The correlation between ZDC and CTB that had been observed in the 130 and 200 GeV data sets was not seen in the lower energy collisions. To approximate a minimum bias trigger, events were selected if they satisfied either a minimum ZDC threshold or a minimum CTB threshold. Triggering will be a resolvable issue for the future beam energy scan.

  3. The STAR 19.6 GeV Au+Au Data Set • One day of running • 12 data runs • Total recorded events = 175466 • Events with good vertex = 42412 • 10% centrality events = 5106

  4. Centrality Determination The mid-y (|h|<0.5) charged particle multiplicity is shown on the left for the four RHIC collision energies. The cut lines correspond to percentages of the total minimum bias cross section. Note the 20 GeV trigger had inefficiencies for collisions in the impact parameter range corresponding to 10-30% and 70-100% Using a Glauber Model, we estimate that our 0-10% data selection had an average number of participant sof 337.

  5. Spectra as a Function of Centrality 200 GeV AuAu and pp data STAR PRL92, 112301 (2003) STAR PRELIMINARY Identified Hadron spectra at mid-rapidity are displayed for several centrality selctions.

  6. Charged Particle Spectra Compared SPS The central mid-rapidity spectra are displayed against the most comparable SPS spectra STAR PRELIMINARY NA44 PRC66, 044907 (2002) - all NA49 PRC66, 054902 (2002) - pim, kam, and kap NA49 PRC69, 024902 (2004) - protons NA49 nucl-ex/0512033 - protons and anti-protons WA98 PRL83, 926 (1999) - pi-zero WA98 NPA698, 647 (2002) - pim WA98 PRC67, 014906 (2003) - pim and kam

  7. Correcting the Comparisons Energy Dependence Centrality (Np) Effect Studied the rapidity densities, then determine the effect of the rapidity slice for each particle NA49 rapidity density data N(A661, 45c (1999)

  8. Comparisons of Pion Yields Fit all experimental data with exponential over the range 200-800 MeV/c2 Fix temperature to 185 and corre t for difernces in centrality, rapidity, and beam eanergy STAR PRELIMINARY

  9. Kaon Yields Fit all experimental data with exponential over the range 100-600 MeV/C2 STAR PRELIMINARY Fix temperature to 250 and corre t for difernces in centrality, rapidity, and beam eanergy

  10. Proton Yields – Corrected for Feed-down Fit all experimental data with exponential over the range 200-800 MeV/c2 Fix temperature to 300 and corre t for difernces in centrality, rapidity, and beam eanergy STAR PRELIMINARY * STAR Data are corrected using NA49 Lambda and anti-Lambda results

  11. Fitting the Shape of the Spectra In order to estimate the integrated yield, the spectral shapes are modeled and extrapolated STAR PRELIMINARY

  12. Radial Flow Analysis 200 GeV data STAR PRL92, 112301 (2003) STAR PRELIMINARY FoPi NPA612, 493 (1997) FoPi NPA610, 49c (1996) EOS PRL75, 2662 (1995) E866 APPB29, 3253 (1998) NA44 PRL78, 2080 (1997) NA49 PRL82, 2471 (1999) PHENIX NPA715, 498 (2003) BRAHMS nucl-ex/0404011 STAR PRL92, 112301 (2003) Statistical Model: Tch = 164.7 +/- 0.5 mB = 205.5 +/- 0.6 mS = 27.2 +/- 0.9

  13. Rapidity Density Distributions NA44 PRC66, 044907 (2002) - all NA49 PRC66, 054902 (2002) - pim, kam, and kap NA49 PRC69, 024902 (2004) - protons NA49 nucl-ex/0512033 - protons and anti-protons WA98 PRL83, 926 (1999) - pi-zero WA98 NPA698, 647 (2002) - pim WA98 PRC67, 014906 (2003) - pim and kam The yields are studied as a function of rapidity and centrality STAR PRELIMINARY STAR PRELIMINARY STAR PRELIMINARY

  14. Particle Ratios STAR PRELIMINARY E802 NPA610, 139c (1996) E802 PRL81, 2650 (1998) E866 PLB476, 1 (2000) E917 PLB490, 53 (2000) NA49 PRC66, 054902 (2002) NA44 PRC66, 044907 (2002) PHENIX PRC69, 034909 (2004) STAR PRL92, 112301 (2003) STAR PLB595, 143 (2004) STAR PRL86, 4778 (2001) STAR PLB567, 167 (2003)

  15. K/p Ratios STAR PRELIMINARY E802 PRL81, 2650 (1998) E866 PLB476, 1 (2000) E917 PLB490, 53 (2000) NA44 PLB471, 6 (1999) WA98 PRC67, 104906 (2003) NA49 PRC66, 054902 (2002) NA49 EPJC33, S621 (2004) NA49 arXiv:0710.0118v2 PHENIX PRC69, 034909 (2004) PHENIX PRL88, 242301 (2002) STAR PRL92, 112301 (2003) STAR PLB595, 143 (2004)

  16. Pion Ratios The pion ratios are fit with a coulomb model. The extracted potential of the source is 8.5 MeV STAR PRELIMINARY KaoS PLB420, 20 (1998) E866 NPA610, 139c (1996) NA44 PLB372, 339 (1996) WA98 nucl-ex/0607018 STAR PRL92, 112301 (2003)

  17. „Standard”  HBT analysis • impressive agreement: STAR Au+Au @19.6GeV with CERES/NA49 Pb+Pb @17.3 GeV • weak s dependence of HBT cancels weak Abeam dependence --> ~apples:apples • Scale andp-dep. of homogeneity regions • follow already-established trends • disfavor signals of increased lifetimes at intermediate collision energies Slide courtesy of Z. Chajecki and M. Lisa

  18. Summary • We have measured the pion, kaon, and proton spectra in 19.6 GeV Au+Au collisions • These spectra have been measured as a function of rapidity and centrality • Detailed comparisons of these spectra to the published SPS results have been made, in most cases the results are compatible. • The RHIC Beam Energy Scan will be able to reduce the statistical and systematic errors.

  19. Backup Slides

  20. STAR PRELIMINARY STAR PRELIMINARY STAR PRELIMINARY

  21. 2001 19.6 GeV Au+Au collisions STAR PHENIX Figure from T. Satogata • 2 days of 9.8 GeV beams • 0.4 mb-1 integrated luminosity • *=3m by necessity • 60-90 minute stores • 56 Au bunches, 0.6x109/bunch • 10-30 Hz ZDC rates • IBS and aperture dominated beam and luminosity lifetime • Another run at this energy may improve this by factor of 2-5 • 1.0+x109/bunch • Raise * to improve lifetime • RHIC is best used as a storage ring collider below beam energies of ~12 GeV

  22. Added 62.5

  23. Studied the production trends as a function of Np and root S Parameterized the energy dependence Flat as a function of Np for central collisions

  24. STAR PRELIMINARY

  25. p- STAR NA49 WA98 NA44 STAR PRELIMINARY

  26. p+ STAR WA98 NA44 STAR PRELIMINARY

  27. K- STAR NA49 WA98 NA44 STAR PRELIMINARY

  28. K+ STAR NA49 NA44 STAR PRELIMINARY

  29. p- STAR NA49 NA44 STAR PRELIMINARY

  30. p+ STAR NA49 NA44 STAR PRELIMINARY

  31. Proton Yields before correction Fit all experimental data with exponential over the range 200-800 MeV/c2 Fix temperature to 300 and corre t for difernces in centrality, rapidity, and beam eanergy STAR PRELIMINARY * Corrected for hyperon feeddown

  32. STAR 62.5 2.72 +/- 0.24 200 3.94 +/- 0.28 STAR PRELIMINARY PRC 71, 0344908 (2005) • PHENIX • 19.6 1.86 +/- 0.15 • 3.46 +/- 0.18 • 200 3.89 +/- 0.23 NA49 17.2 1.86 +/- 0.08 12.4 1.54 +/- 0.07 8.7 1.24 +/- 0.06 NA45 17.2 1.87 +/- 0.19 8.7 1.35 +/- 0.08 NA50 17.2 1.98 +/- 0.16 8.7 0.95 +/- 0.10

  33. NA44 STAR PRELIMINARY NA49

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