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Critical Point Scans at RHIC Full Energy

Critical Point Scans at RHIC Full Energy. Paul Stankus “The QCD Critical Point Workshop” INT, Aug 13, 2008. How much experimental control do we have?.  ?. n B / s is a “figure of merit” for any isentropic trajectory. E. Shuryak, POS (CPOD2006) 026. “All thermodynamics is local”.

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Critical Point Scans at RHIC Full Energy

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  1. Critical Point Scans at RHIC Full Energy Paul Stankus “The QCD Critical Point Workshop” INT, Aug 13, 2008

  2. How much experimental control do we have? ? nB/s is a “figure of merit” for any isentropic trajectory E. Shuryak, POS (CPOD2006) 026

  3. “All thermodynamics is local” Yorz Scaling Solution:(not restricted to Bjorken hydrodynmaics) Fluid at/near position z at some time Fluid velocity at/near some rapidity Y at that time

  4. BRAHMS PRL 94 (2005) 162301 BRAHMS PRL 93 (2004) 102301 p B RHIC Au+Au 200 GeV Central

  5. Greater Baryon Stopping Early Hydro Nominal Baryon Stopping Baryon Re-Acceleration! B Initial s Late Hydro B

  6. B/p Rapidity Scan p B RHIC Au+Au 200 GeV Central x20

  7. Every collision contains a scan! B/p

  8. 62 BRAHMS Preliminary BRAHMS H.H. Dalsgaard QM2008 BRAHMS I.C. Arsene QM2008 17 NA49 PRC 56 (2002) 054902 NA49 PRL 82 (1999) 2471

  9. B/p Beam Energy Scan x10 √sNN = 2006217

  10. B/p Asymmetric Beam Energies A 100 AGeV + 10 AGeV collision has √sNN ≈ 60 GeV and ∆YCMS ≈ 1.15 200 100+106217

  11. Asymmetric Ion Collisions: NPart Central b=0 Au+Au Cu+Au Si+Au

  12. Asymmetric Ion Collisions: dN/dY dNB/dY Au+Au 115/194 Cu+Au 64/194 p 64+115  194+194 Assume: Each dNB/dY scales as NPart, and dNp/dY scales as NPart1+NPart2 B

  13. Asymmetric Ion Collisions: B/p B/p Cu+Au Au+Au Under simple NPart scaling, if fNPart1/ NPart2 then B/p changes by a factor of 2/(1+f) relative to symmetric collisions.

  14. Shifting p’s relative to B’s +0.3 p WA80 PRC 44 (1991) 2736 B B/p Au+Au Cu+Au

  15. Summary: For isentropic evolution, nB/s is conserved for a fluid element. We can approximate nB/s for a fluid element by B/p at some rapidity Y in the final state. At full RHIC energy B/p is a strong function of rapidity, varying over a factor of 20 from Y0 to Y4. Effectively every collision contains a scan in nB/s. Beam energy scans from top RHIC to top SPS vary B/p by about a factor of 10 at mid-rapidity. Asymmetric beam energy collisions can shift the B/p pattern significantly. Asymmetric ion collisions at RHIC are of fundamental interest for many reasons but don’t provide much leverage in B/p, under simple assumptions.

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