121092449
Probing dense nuclear matter in the laboratory
A 150‐meter‐long outdoor beam line wanders through eucalyptus trees down the 45‐meter slope connecting the SuperHILAC and the Bevatron at the Lawrence Berkeley Laboratory. The SuperHILAC is a linear accelerator designed to accelerate heavy nuclei at high intensities to energies of up to 8 MeV/nucleon for the purpose of studying heavy and superheavy elements. The Bevatron is a weak focusing synchrotron born in 1954 with the mission of discovering the antiproton and exploring the riddle of the hadrons using beams of 6.2‐GeV protons. In 1974 these two machines were coupled to create the Bevalac, and with it a new field of research: relativistic heavy‐ion reactions.
119186084
Bimodality and Coulomb effects with a canonical thermodynamic model
Abstract The effect of the Coulomb interaction on the phase diagram of finite nuclei is studied within the Canonical Thermodynamic Model. If Coulomb effects are artificially switched off, this model shows a phenomenology consistent with the liquid–gas phase transition. The inclusion of Coulomb does not significantly affect the phase diagram but it drastically modifies the nature and order parameter of the transition. A clear understanding of the phenomenon can be achieved looking at the distribution of the largest fragment produced in each fragmentation event. Possible connections with experimental observations are outlined.
2820708
Transverse momenta, nuclear equation of state, and momentum-dependent interactions in heavy-ion collisions.
We investigate the generation of transverse momentum in high-energy heavy-ion collisions and its relation to the nuclear equation of state. We find that streamer chamber data can be fitted by Boltzmann-Uehling-Uhlenbeck calculations with a momentum-dependent potential that closely models realistic nuclear matter interactions and yields an equation of state with {ital K}=215 MeV.
14927510
A Transport Model for Nuclear Reactions Induced by Radioactive Beams
Major ingredients of an isospin and momentum dependent transport model for nuclear reactions induced by radioactive beams are outlined. Within the IBUU04 version of this model we study several experimental probes of the equation of state of neutron‐rich matter, especially the density dependence of the nuclear symmetry energy. Comparing with the recent experimental data from NSCL/MSU on isospin diffusion, we found a nuclear symmetry energy of Esym(ρ) ≈ 31.6(ρ/ρ0)1.05 at subnormal densities. Predictions on several observables sensitive to the density dependence of the symmetry energy at supranormal densities accessible at GSI and the planned Rare Isotope Accelerator (RIA) are also made.
121836312
Excluded volume in nuclear fragmentation
16308546
First Order Phase Transition in Intermediate-Energy Heavy Ion Collisions
We model the disassembly of an excited nuclear system formed as a result of a heavy ion collision. We find that, as the beam energy in central collisions in varied, the dissociating system crosses a liquid-gas coexistence curve, resulting in a first-order phase transition. Accessible experimental signatures are identified: a peak in specific heat, a power-law yield for composites, and a maximum in the second moment of the yield distribution.
121323084
Microscopic nucleon optical model potential at low energies
Nuclear optical model potentials at low energies have been computed utilizing the two (Micro I and Micro II) versions of the microscopic optical model of Jeukenne et al. A comparison has been made of the experimental nucleon-nucleus interaction data for E<10 MeV with the theoretical predictions obtained using the microscopic optical model.
122488620
Working group report: Quark gluon plasma
The 10th Workshop on High Energy Physics Phenomenology (WHEPP-10) was held at the Institute of Mathematical Sciences, Chennai during January 2–13, 2008. One of our working grops (WG) is QCD and QGP. The discussions of QGP WG include matter at high density, lattice QCD, charmonium states in QGP, viscous hydrodynamics and jet quenching, colour factor in heavy ion collisions and RHIC results on photons, dileptons and heavy quark. There were two plenary talks and several working group talks with intense discussions regarding the future activities that are going to be persued.
120031477
Theory of Longitudinal Photons in Quantum Electrodynamics
The radiation field is quantized by introducing four types of photons - two transverse, one longitudinal, and one scalar. The scalar photons are treated by using an indefinite metric, and it is found necessary to modify the usual supplementary condition slightly. The present theory offers a justification for the symmetrical treatment of the four components of the electromagnetic potential, recently applied by a number of authors, and proves to be very convenient in applications. The results of physical interest, however, are the same as obtained from the ordinary formulation.
118666767
Relativistic diffusion and heavy-ion collisions
We study first- and second-order theories of relativistic diffusion coupled to hydrodynamics under the approximation, valid at midrapidity in the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC), that conserved number densities are much smaller than the entropy density. We identify experimentally accessible quantities of interest and show that the first- and second-order theories may lead to radically different evolutions of these quantities. In the first-order theory the memory of the initial state is almost completely washed out, whereas in the second-order theory it is possible that freeze-out occurs at a time when transient dynamics is still on and the memory of the initial state remains. There are observational consequences that we touch upon. In the first-order theory, and for initial conditions when the second-order theory mimics the first-order theory, one may be able to put a bound on the diffusion constant.
116159225
Upper Limit on the Diffuse Gamma Ray Flux Using Air Shower Observations at Ooty