Laying the groundwork at the AGS: Recent results from E895 Mike Lisa, for the E895 Collaboration N.N.
Download ReportTranscript Laying the groundwork at the AGS: Recent results from E895 Mike Lisa, for the E895 Collaboration N.N.
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, 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 E895 Mike Lisa, Quark Matter 2001 1 Reminder: why AGS is (still) interesting spp sets baseline systematics “your systematics deviate from what?” Fy before E895 v the “other” extreme condition 2 - maximum baryon density probe medium & bulk b effects transition region for bulk properties E895 T Mike Lisa, Quark Matter 2001 Ebeam 2 This talk Not a “final wrap-up” of E895, which is still alive. Since QM99: • • • • • • PRL 83 1295 (1999) PRL 84 2798 (2000) PRL 84 5488 (2000) PRL 85 940 (2000) PLB 496 1 (2000) PRL accepted (2000) E895 Transition from out-of-plane to in-plane elliptic flow Bombarding energy dependence of p- HBT at the AGS Sideward flow in Au+Au collisions at 2-8 AGeV Anti-flow of K0 mesons in 6 AGeV Au+Au collisions Azimuthal dependence of pion interferometry 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 • L-p correlations • Summary Mike Lisa, Quark Matter 2001 3 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) E895 “Grandfather of STAR TPC” Mike Lisa, Quark Matter 2001 4 p phasespace density The Four Fundamental Corners of E895 thermal population? multiparticle effects? poster by D. Cebra space-time geometry & dynamics thermal/chemical properties PRL 84 2798 (2000) poster by J. Klay tilted sources geometry of anisotropic flow L-p correlations baryon source geometry two-hadron potential PLB 496 1 (2000) poster by U. Heinz pre-equilibrium dynamics collective bulk response equation of state PRL 83 1295 (1999) PRL 84 5488 (2000) E895 strange/nonstrange radial flow distinct freezeout? talk by C. Pinkenburg L, K0 flow strange potentials PRL 85 940 (2000) PRL, in press talk byQuark C. Pinkenburg Mike Lisa, Matter 2001 early thermochemistry strange potentials talk by C. Pinkenburg 5 d px sideward flow dyn v2 cos2 elliptic flow F F (GeV/c) Reminder from QM99: Proton Flow 0.3 0.2 0.1 0 0.04 10 1 10 Elab (AGeV) v2 Transition region for flow mapped Momentum space F drops as presonances dominate y px Strong sensitivity to medium contributions to pressure qF No single parameterization p z reproduces flow details (Beam) plane No sudden drops Reaction in pressure (flow) signaling phase transition 0 -0.04 -0.08 E895 1 1 Elab (AGeV) 10 Mike Lisa, Quark Matter 2001 PRL 83 1295 (1999) PRL 84 54886(2000) K s0 p p- Beyond protons... neural networks identify decays of neutral strange particles L production excitation function L p pL Minv (GeV/c2) • (p+p)•179 E895 1.08 1.10 1.12 1.14 2) see 2001 talk of Chris Pinkenburg7today MMike Lisa, Quark Matter inv (GeV/c L flow • “positive” L flow • decreases with Eb (more than p) 2 AGeV px (GeV/c) • RQMD (without L potential) underpredicts effect • probe L potential at high r (complements hypernuclei studies) astrophysical models 4 AGeV “quark counting” 6 AGeV E895 NL 23 NN y/ycm PRL accepted (2000) see 2001 talk Mike Lisa, Quark Matter of Chris Pinkenburg8 today K0S (anti-)flow Surprise— strong antiflow • grows with collision energy px (GeV/c) 0.1 S. Pal et al, PR C62 061903 (2000) 0 -0.1 6 GeV -1.0 data RQMD (2.3) 4 GeV data -0.5 0 y/ycm 0.5 1.0 Transport models: • rescattering insufficient (results in positive flow) • strong repulsive vector potential required E895 PRL 85 940 (2000) see 2001 talk Mike Lisa, Quark Matter of Chris Pinkenburg9today proton elliptic flow - varying the geometry 0 -.02 2 AGeV -.04 D .02 v2 “min-bias” flow measurements do not constrain models geometry provides another handle on flow 4 AGeV 0 increasing spatial asymmetry produces larger signal -.02 6 AGeV .01 -.01 0 E895 Can HBT give geometrical information on flow?? 2 4 b (fm) 6 8 Mike Lisa, Quark Matter 2001 10 HBT: probing freeze-out space-time structure I - Cylindrical sources ~2 K ~ x out - b t 2 2 ~ R s K x side K ~2 2 Rl K ~ x long - bl t R o2 K Rside E895 K K ~ xx- x d 4 x S( x, K ) f ( x ) f 4 d x S( x, K) x out , x side x, y Rout HBT @ AGS mapped by E895 (QM99) PRL 84, 2798 (2000) NPALisa, 661, 444c (1999) Mike Quark Matter 2001 11 HBT: probing freeze-out space-time structure II - Collisions at b0 side y •Source in b-fixed system: (x,y,z) •Space/time entangled in pair system (xO,xS,xL) R o2 R s2 2 R os ~y ~y - 12 1 2 1 2 cos2 ~y sin 2 2 - ~ x2 - ~ x2 1 2 2 ~ x2 out ~ ~y 2 - ~ x 2 cos 2 12 ~y 2 ~ x 2 b2 t 2 2 K x b ~ R l2 ~z 2 b2L t 2 2 R ol ~ x ~z cos R2 - ~ x ~z sin sl E895 (several terms vanish @ pT = y = 0) U. Wiedemann, PRC 57, 266 (1998) MAL, U. Heinz, U. Wiedemann PLB 489, 287 (2000) Poster by U. Heinz Mike Lisa, QuarkSee Matter 2001 12 First-order information in HBT() y 2nd-harmonic oscillations from elliptical transverse shape ~y ~y cos2 ~y sin 2 ~ x2 ~y 2 b 1 x ~ R o2 - 12 ~y 2 - ~ x 2 cos 2 12 ~y 2 ~ x 2 b2 t 2 R s2 2 R os 1 2 1 2 2 2 - ~ x2 - ~ x2 ~ R l2 ~z 2 b2L t 2 1 2 2 ~ x2 st-harmonic oscillations: spatial tilt angle qS y x qs 2 R ol ~ x ~z cos R2 - ~ x ~z sin z (Beam) sl E895 Coordinate space! Mike Lisa, Quark Matter 2001 13 Data: p- correlation functions Au(4 AGeV)Au, b4-8 fm 2D projections C(q) 1D projections, =45° out side long lines: projections of 3D Gaussian fit - q i q j R ij2 C(q, ) 1 e • 6 components to radius tensor: i, j = o,s,l E895 E895, PLB 496 1 (2000) Mike Lisa, Quark Matter 2001 14 Cross-term radii Rol, Ros, Rsl quantify “tilts” in correlation functions fit results to correlation functions Lines: Simultaneous fit to HBT radii to extract underlying Mike Lisa, Quarkgeometry Matter 2001 E895 15 Images of p--emitting sources (scaled ~ x1014) ~y 2 1.35 2 ~ x y similar to naïve overlap: b~5 fm y x’ x’ 2 AGeV 3 fm z y qS=47° x’ 4 AGeV z 6 AGeV qS=37° z qS=33° Large, positive tilt angles E895 x Mike Lisa, Quark Matter 2001 x x 16 Opposing average tilts in p, x and the physics of p flow p+ 6 AGeV • p “antiflow” (negative tilt in p-space) • x-space tilt in positive direction non-hydro nature of p flow z (fm) RQMD transport model: • Antiflow reflects dense region z~0 • (dilute large-|z| show positive flow) B. Caskey pion momentum anisotropies due to reflection from flowing baryons (pND pN) p tilt reflects x-space structure of proton flow E895 Bass et al [PLB 302 381 (93)]: Mike Lisa, Quark Matter 2001 RQMD Au(2GeV)Au x (fm) 17 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 dimensional Tomography of proton flow 6 AGeV Momentum Space (Flow) pz py Tiny flow angle px E895 Coordinate Space (HBT) z positive v2 px y Large tilt Mike Lisa, Quark Matter 2001 x Out-of-plane x’ 18 More on position - momentum space relationship the phasespace density f = occupation of 6-D positionmomentum cell, volume h3 • determines magnitude of multi-particle correlations (lasers) • provides a test of thermalization/consistency f ( x , p) 1 e pu ( x ) / T ( x ) - 1 T determines number of p, as well as spectral shape Experimental access to spatially averaged density 1 d3 N E dy pT dpT d f pT , y p3 R out R side R long volume in p-space volume in x-space G. Bertsch, PRL 72 2349 (94) D. Ferenc et al, PL B457 347 (99) • observation @ SPS, AGS: “Universal” p freeze-out density E895 • breaks down at lower Mike energies? Lisa, Quark Matter 2001 19 Measured phasespace densities • non-universal growth of f with collision energy • f<1 no condensate E895 preliminary Mike Lisa, Quark Matter 2001 midrapidity central collisions 20 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! E895 preliminary Mike Lisa, Quark Matter 2001 midrapidity central collisions 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! • Rough agreement with thermal Bose-Einstein • high-pT excess @ high Eb E895 preliminary Mike Lisa, Quark Matter 2001 midrapidity central collisions 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 • Better description by inclusion of radial flow [B. Tomasik, Ph.D. thesis] • Substantial experimental & theoretical uncertainties E895 preliminary also see poster of D. Cebra Mike Lisa, Quark Matter 2001 midrapidity central collisions 23 Baryon correlations C2 • Lp more sensitive than pp? 1.2 • Correct Lp potential? 1.8 1.0 1.6 0.8 1.4 2 AGeV 4 AGeV 6 AGeV O 8 AGeV 0.6 1.2 1.0 C2 0.4 pp correlation function (central collisions, y<ycm) 0.2 0 L-p 0 0.4 0.8 0.12 k (GeV/c) • pp correlations ~ Ebeam independent • another handle on baryon source? E895 1.2 p-p 1.0 0.8 0.6 0.4 0.2 0 20 40 k (MeV/c) Wang & S. Pratt PRL 83 3139 Mike Lisa, Quark MatterF. 2001 24 (1999) Another E895 first: L-p correlation function • positive correlation observed 1.4 • work in progress… E895 1.0 C(k) • qualitatively different shape than expected from Urbana p-L potential input to the particle physics 0.6 1.4 1.0 0.6 0 20 Mike Lisa, Quark Matter 2001 40 60 80 100 k (MeV/c) 25 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 E895 Mike Lisa, Quark Matter 2001 26 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 E895 Mike Lisa, Quark Matter 2001 27 More E895 @ QM01 Production & Collective Behaviour of Strange Particles Parallel session today: Chris Pinkenburg p Phasespace Density & Source Charge Density P063 Dan Cebra Directed, Elliptic, Radial, & Longitudinal Flow P069 Jenn Klay Azimuthally-sensitive HBT and the Tilt of the p Source P018 Ulrich Heinz* E895 Mike Lisa, Quark Matter 2001 * honorary E895 member 28 Pion and proton elliptic flow E895 Mike Lisa, Quark Matter 2001 W. Caskey, DNP98 • Ellitpic flow of both positive and negative pions follows the trends of the protons 29