Elliptic flow: transition from out-of-plane to in-plane emissionin Au + Au collisions

Journal Article · Sat Jul 31 04:00:00 EDT 1999 · Physical Review Letters

OSTI ID:893738

Pinkenburg, C; Ajitanand, N N; Alexander, J M; Anderson, M; Best, D; Brady, F P; Case, T; Caskey, W; Cebra, D; Chance, J L; Chung, P; Cole, B; Crowe, K; Das, A C; Draper, J E; Elmaani, A; Gilkes, M L; Gushue, S; Heffner, M; Hirsch, A S ; Hjort, E L; Huo, L; Justice, M; Kaplan, M; Keane, D; Kintner, J C; Klay, J; Krofcheck, D; Lacey, R A; Lauret, J; Law, C; Lisa, M A; Liu, H; Liu, Y M; McGrath, R; Milosevich, Z; Odyniec, G; Olson, D L; Panitkin, S Y; Porile, N T; Rai, G; Ritter, H G; Romero, J L; Scharenberg, R P; Schroeder, L; Srivastava, B; Stone, N T.B.; Symons, T J.M.; Whitfield, J; Wienold, T; Witt, R; Wood, L; Zhang, W N; Danielewicz, P; Gossiaux, P B

We have measured the proton elliptic flow excitation function for the Au+Au system spanning the beam energy range (2-8)A GeV. The excitation function shows a transition from negative to positive elliptic flow at a beam energy, Etr {approx} 4A GeV. Detailed comparisons with calculations from a relativistic Boltzmann equation are presented. The comparisons suggest a softening of the nuclear equation of state from a stiff form (K {approx} 380 MeV) at low beam energies (Ebeam < 2A GeV) to a softer form (K {approx} 210 MeV) at higher energies ( Ebeam < 4A GeV) where the calculated baryon density rho {approx} 4 rho 0.

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE Director, Office of Science. Office of High Energy andNuclear Physics
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 893738
• Report Number(s): LBNL--44086
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 73 Vol. 83; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BARYONS
BOLTZMANN EQUATION
ENERGY RANGE
EXCITATION FUNCTIONS
PROTONS