The spacetime evolution of superdense matter in ultrarelativistic nuclear collisions

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7197376

Venugopalan, R

In this work, various aspects are studied of the thermodynamics, kinetics and hydrodynamics of the superdense matter formed in ultrarelativistic nuclear collisions. In chapter II, the thermodynamics are studied of hadronic matter at temperatures near the pion mass. The relativistic virial expansion is used to investigate the thermodynamics of an interacting [pi]K N gas. Limits on the range of schematic models of the resonance gas phase are established by causality constraints. Phase diagrams are constructed. In chapter III, equilibration of hot hadronic matter is studied using relativistic kinetic theory. Relaxation times, collision times and mean free paths are calculated for a [pi]K N mixture. The viscosity, thermal conductivity, diffusion and thermal diffusion coefficients are calculated in the Chapman-Enskog formalism. This formalism is extended to extract transport relaxation times. A plausible solution is proposed to a longstanding puzzle about collective flow effects on the p[sub t] (transverse momentum) spectra of kaons and nucleons versus those of pions. In chapter IV, a 3-d hydrodynamic model is developed and used, for various initial conditions (IC) and equations of state (EOS), to compute spectral distributions of particles emerging from collective flow. Spectral observables are insensitive to the different EOS. It is found that (p[sub t]) (average transverse momentum) versus multiplicity softens when matter undergoes a change of phase. A strong correlation is observed between (p[sub t]) and the rapidity. The spectra are extremely sensitive to the IC in the thermalized fluid. Fits to NA35 data for S + S collisions at 200 GeV/nucleon at CERN indicate that the rapidity and p[sub t] data can be fit only for large initial longitudinal flows. Fairly good fits to the rapidity and p[sub t] data above p[sub t] = 250 MeV can be obtained for decoupling temperatures T[sub dec] [approximately] 120 MeV with small adjustments in the IC and T[sub dec].

• Research Organization: State Univ. of New York, Stony Brook, NY (United States)
• OSTI ID: 7197376
• Country of Publication: United States
• Language: English

Related Subjects

663300* -- Nuclear Reactions & Scattering
General-- (1992-)
665000 -- Physics of Condensed Matter-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOMS
COLLISIONS
ENERGY RANGE
EQUATIONS
EQUATIONS OF STATE
HADRONIC ATOMS
HYDRODYNAMIC MODEL
MATHEMATICAL MODELS
MEAN FREE PATH
PARTICLE KINEMATICS
PARTICLE MODELS
RELATIVISTIC RANGE
RELAXATION TIME
SPACE-TIME
STATISTICAL MODELS
THERMODYNAMIC MODEL
VIRIAL EQUATION