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Laying the groundwork at the AGS: Recent results from E895 Mike Lisa, for the E895 Collaboration

Laying the groundwork at the AGS: Recent results from E895 Mike Lisa, for the E895 Collaboration. N.N. Ajitanand, J. Alexander, D. Best, P. Brady, T. Case, B. Caskey , D. Cebra,

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Laying the groundwork at the AGS: Recent results from E895 Mike Lisa, for the E895 Collaboration

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  1. Laying the groundwork at the AGS:Recent results from E895Mike Lisa, for the E895 Collaboration N.N. Ajitanand, J. Alexander, D. Best, P. Brady, T. Case, B. Caskey, D. Cebra, J. Chance, P. Chung, B. Cole, K. Crowe, A. Das, J. Draper, S. Gushue, M. Gilkes, M. Heffner, H. Hiejima, A. Hirsch, E. Hjort, L. Huo, M. Justice, M. Kaplan, J. Klay, D. Keane, J. Kintner, D. Krofcheck, R. Lacey, J. Lauret, E. LeBras, M. Lisa, H. Liu, Y. Liu, B. McGrath, Z. Milosevich, D. Olson, S. Panitkin, C. Pinkenburg, N. Porile, G. Rai, H.-G. Ritter, J. Romero, R. Scharenberg, L. Schroeder, B. Srivastava, N. Stone, J. Symons, S. Wang, R. Wells, J. Whitfield, T. Wienold, R. Witt, L. Wood, X. Yang, Y. Zhang, W. Zhang Auckland - BNL - CMU - Columbia - UC Davis - Harbin - KSU - LBL - St. Mary’s College - OSU - Purdue - Stony Brook Mike Lisa, Quark Matter 2001

  2. before E895 Reminder: why AGS is (still) interesting spp • sets baseline systematics“your systematics deviate from what?” • the “other” extreme condition - maximum baryon density • probe medium & bulk effects • transition region for bulk properties Fy v2 b T Ebeam Mike Lisa, Quark Matter 2001

  3. This talk • Not a “final wrap-up” of E895, which is still alive. Since QM99: • PRL 83 1295 (1999) Transition from out-of-plane to in-plane elliptic flow • PRL 84 2798 (2000) Bombarding energy dependence of p- HBT at the AGS • PRL 84 5488 (2000) Sideward flow in Au+Au collisions at 2-8 AGeV • PRL 85 940 (2000) Anti-flow of K0 mesons in 6 AGeV Au+Au collisions • PLB 496 1 (2000) Azimuthal dependence of pion interferometry • PRL accepted (2000) L flow in 2-6AGeV Au+Au collisions • Published E895 flow • Beyond proton flow - collective flow of strange particles • Geometrical dependence of flow • HBT Beyond “Rp = 5 fm” • geometric aspects of collective flow • 6D phasespace density • -p correlations • Summary Mike Lisa, Quark Matter 2001

  4. Measurement with the EOS TPC • Up to ~350 particles/event measured over large phase space • Good reaction plane resolution • p/p  3% (dominated by MCS) “Grandfather of STAR TPC” Mike Lisa, Quark Matter 2001

  5. Mike Lisa: make bigger fonts!!!! p phasespace density thermal population? multiparticle effects? Spectra poster by D. Cebra HBT thermal/chemical properties space-time geometry & dynamics poster by J. Klay PRL 84 2798 (2000) L-p correlations strange/nonstrange radial flow tilted sources baryon source geometry two-hadron potential geometry of anisotropic flow distinct freezeout? PLB 496 1 (2000) talk by C. Pinkenburg poster by U. Heinz Flow Strangeness pre-equilibrium dynamics collective bulk response equation of state early thermochemistry strange potentials L, K0 flow strange potentials talk by C. Pinkenburg PRL 83 1295 (1999) PRL 85 940 (2000) PRL, in press PRL 84 5488 (2000) talk by C. Pinkenburg The Four Fundamental Corners of E895 Mike Lisa, Quark Matter 2001

  6. 0.3 F (GeV/c) 0.2 0.1 0 10 10 1 1 0.04 Elab (AGeV) v2 py 0 px qF -0.04 pz (Beam) -0.08 Reaction plane 10 1 Elab (AGeV) Reminder from QM99: Proton Flow sideward flow elliptic flow • Transition region for flow mapped • F drops as resonances dominate • Strong sensitivity to medium contributions to pressure • No single parameterization reproduces flow details • No sudden drops in pressure (flow) signaling phase transition Momentum space PRL 83 1295 (1999) PRL 84 5488 (2000) Mike Lisa, Quark Matter 2001

  7. • (p+p)•179 1.08 1.10 1.12 1.14 Minv (GeV/c2) Beyond protons... neural networks identify decays of neutral strange particles L production excitation function L Minv (GeV/c2) see talk of Chris Pinkenburg today Mike Lisa, Quark Matter 2001

  8. L flow • “positive” L flow • decreases with Eb (more than p) • RQMD (without L potential) underpredicts effect • probe L potential at high r (complements hypernuclei studies)  astrophysical models 2 AGeV 4 AGeV  px  (GeV/c) “quark counting” 6 AGeV y/ycm see talk of Chris Pinkenburg today PRL accepted (2000) Mike Lisa, Quark Matter 2001

  9. 0.1 S. Pal et al, PR C62 061903 (2000) px (GeV/c) 0 data 6 GeV RQMD (2.3) -0.1 4 GeV data -1.0 -0.5 0 0.5 1.0 y/ycm • Transport models: • rescattering insufficient (results in positive flow) • strong repulsive vector potential required K0S (anti-)flow • Surprise— strong antiflow • grows with collision energy see talk of Chris Pinkenburg today PRL 85 940 (2000) Mike Lisa, Quark Matter 2001

  10. proton elliptic flow - varying the geometry 0 -.02 “min-bias” flow measurements do not constrain models  geometry provides another handle on flow increasing spatial asymmetry produces larger signal Can HBT give geometrical information on flow?? 2 AGeV -.04 D .02 4 AGeV 0 v2 -.02 6 AGeV .01 -.01 0 2 4 6 8 b (fm) Mike Lisa, Quark Matter 2001

  11. K HBT @ AGS mapped by E895 (QM99) PRL 84, 2798 (2000) NPA 661, 444c (1999) Rout Rside HBT: probing freeze-out space-time structure I - Cylindrical sources Mike Lisa, Quark Matter 2001

  12. HBT: probing freeze-out space-time structure II - Collisions at b0 side y K • Source in b-fixed system: (x,y,z) • Space/time entangled in pair system (xO,xS,xL) out f x b (several terms vanish @ pT = y = 0) U. Wiedemann, PRC 57, 266 (1998) MAL, U. Heinz, U. Wiedemann PLB 489, 287 (2000) See Poster by U. Heinz Mike Lisa, Quark Matter 2001

  13. y 2nd-harmonic oscillations from elliptical transverse shape x b 1st-harmonic oscillations: spatial tilt angle qS y x qs z (Beam) Coordinate space! First-order information in HBT(f) Mike Lisa, Quark Matter 2001

  14. f () Data: p- correlation functionsAu(4 AGeV)Au, b4-8 fm 2D projections 1D projections, f=45° C(q) out side long lines: projections of 3D Gaussian fit • 6 components to radius tensor: i, j = o,s,l E895, PLB 496 1 (2000) Mike Lisa, Quark Matter 2001

  15. f () Cross-term radii Rol, Ros, Rslquantify “tilts” in correlation functions fit results to correlation functions Mike Lisa: thicker lines!!! bigger symbols!! have 2 GeV handy Lines: Simultaneous fit to HBT radii to extract underlying geometry Mike Lisa, Quark Matter 2001

  16. qS=47° qS=33° qS=37° y z y y z z x x ’ x ’ x x ’ x similar to naïve overlap: b~5 fm 3 fm Images of p--emitting sources (scaled ~ x1014) Mike Lisa: 1 fm = 1/4” 2 AGeV 4 AGeV 6 AGeV Large, positive tilt angles Mike Lisa, Quark Matter 2001

  17. p+ 6 AGeV • RQMD transport model: • Antiflow reflects dense region z~0 • (dilute large-|z| show positive flow) z (fm) pion momentum anisotropies due to reflection from flowing baryons (pND pN) p tilt reflects x-space structure of proton flow x (fm) Bass et al [PLB 302 381 (93)]: RQMD Au(2GeV)Au Opposing average tilts in p, x and the physics of p flow • p “antiflow” (negative tilt in p-space) • x-space tilt in positive direction •  non-hydro nature of p flow B. Caskey Mike Lisa, Quark Matter 2001

  18. y z x’ x Tomography in 6 Dimensions Flow analysis and HBT relative to the reaction plane allow a complete characterization of the final state in phase space, get space-momentum correlations 6 dimensionalTomography of proton flow 6 AGeV Momentum Space (Flow) Coordinate Space (HBT) pz py px Tiny flow angle positive v2 px Large tilt Out-of-plane Mike Lisa, Quark Matter 2001

  19. Experimental access to spatially averaged density volume in p-space volume in x-space More on position - momentum space relationshipthe phasespace density • f = occupation of 6-D positionmomentum cell, volume h3 • determines magnitude of multi-particle correlations (lasers) • provides a test of thermalization/consistency T determines number of p, as well as spectral shape G. Bertsch, PRL 72 2349 (94) D. Ferenc et al, PL B457 347 (99) • observation @ SPS, AGS: “Universal” p freeze-out density • breaks down at lower energies? Mike Lisa, Quark Matter 2001

  20. Measured phasespace densities • non-universal growth of f with collision energy • f<1  no condensate midrapidity central collisions preliminary Mike Lisa, Quark Matter 2001

  21. Measured phasespace densities • non-universal growth of f with collision energy • f<1  no condensate • low-pT saturation of f as Ebeam  8 AGeV • same occupancy as STAR! midrapidity central collisions preliminary Mike Lisa, Quark Matter 2001

  22. Measured phasespace densities • non-universal growth of f with collision energy • f<1  no condensate • low-pT saturation of f as Ebeam  8 AGeV • same occupancy as STAR! • Rough agreement with thermal Bose-Einstein • high-pT excess @ high Eb midrapidity central collisions preliminary Mike Lisa, Quark Matter 2001

  23. Measured phasespace densities • non-universal growth of f with collision energy • f<1  no condensate • low-pT saturation of f as Ebeam  8 AGeV • same occupancy as STAR! • Rough agreement with thermal Bose-Einstein • high-pT excess @ high Eb • Better description by inclusion of radial flow[B. Tomasik, Ph.D. thesis] • Substantial experimental & theoretical uncertainties midrapidity central collisions preliminary also see poster of D. Cebra Mike Lisa, Quark Matter 2001

  24. Lp more sensitive than pp? • Correct Lp potential? C2 1.2 1.8 L-p 1.0 1.6 0.8 1.4  2 AGeV  4 AGeV  6 AGeV O 8 AGeV 1.2 0.6 0.4 1.0 C2 1.2 p-p pp correlation function (central collisions, y<ycm) 0.2 1.0 0 0 0.4 0.8 0.12 0.8 k (GeV/c) 0.6 0.4 0.2 0 20 40 k (MeV/c) F. Wang & S. Pratt PRL 83 3139 (1999) Baryon correlations • pp correlations ~ Ebeam independent • another handle on baryon source? Mike Lisa, Quark Matter 2001

  25. Another E895 first: L-p correlation function • positive correlation observed • qualitatively different shape than expected from Urbana p-L potential •  input to the particle physics • work in progress… 1.4 1.0 C(k) 0.6 1.4 1.0 0.6 60 80 100 0 20 40 k (MeV/c) Mike Lisa, Quark Matter 2001

  26. Summary I • continuing to push the envelope… • directed and elliptic flow excitation function • continue input to bulk parameterization • strange particle flow • positive L flow • does not scale with proton flow (naïve 2/3 rule broken) • L potential important to describe flow • strong antiflow of K0’s • strong, repulsive vector potential indicated • Varying geometry (impact parameter): another handle • increased x asymmetry  larger p asymmetry Mike Lisa, Quark Matter 2001

  27. Summary II • azimuthally-sensitive p- HBT • almond-shaped source, (~ entrance-channel geometry) • large positive spatial tilt angles • non-hydro nature of p flow • coordinate-space structure of proton flow • 6-D p phasespace density • non-universal growth of <f> with energy • saturation to “universal” behaviour at 8 AGeV • after 8 AGeV, increased p yield pushed to high pTflow • first p-L signal observed • significant positive correlation • inconsistent with shape expected by Urbana potential Mike Lisa, Quark Matter 2001

  28. More E895 @ QM01 • Production & Collective Behaviour of Strange Particles Parallel session today: Chris Pinkenburg • p Phasespace Density & Source Charge DensityP063Dan Cebra • Directed, Elliptic, Radial, & Longitudinal FlowP069Jenn Klay • Azimuthally-sensitive HBT and the Tilt of the p SourceP018Ulrich Heinz* * honorary E895 member Mike Lisa, Quark Matter 2001

  29. Pion and proton elliptic flow • Ellitpic flow of both positive and negative pions follows the trends of the protons W. Caskey, DNP98 Mike Lisa, Quark Matter 2001

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