J. B. Elliott

Constructing the phase diagram of finite neutral nuclear matter

Author(s): Elliott, J.B.; Moretto, L.G.; Phair, L.; Wozniak, G.L.; Albergo, S.; Bieser, F.; Brady, F.P.; Caccia, Z.; Cebra, D.A.; Chacon, A.D.; Chance, J.L.; Choi, Y.; Costa, S.; Gilkes, M.L.; Hauger, J.A.; Hirsch, A.S.; Hjort, E.L.; Insolia, A.; Justice, M.; Keane, D.; Kintner, J.C.; Lindenstruth, V.; Lisa, M.A.; Matis, H.S.; McMahan, M.; McParland, C.; Muller, W.F.J.; Olson, D.L.; Partlan, M.D.; Porile, N.T.; Potenza, R.; Rai, G.; Rasmussen, J.; Ritter, H.G.; Romanski, J.; Romero, J.L.; Russo, G.V.; Sann, H.; Scharenberg, R.P.; Scott, A.; Shao, Y.; Srivastava, B.K.; Symons, T.J.M.; Tincknell, M.; Tuve, C.; Wang, S.; Warren, P.; Wieman, H.H.; Wienold, T.; Wolf, K.

Negative heat capacities and first order phase transitions in nuclei

The origin of predicted and observed anomalies in caloric curves of nuclei and other mesoscopic systems is investigated. It is shown that a straightforward thermodynamical treatment of an evaporating liquid drop leads to a backbending in the caloric curve and to negative specific heats in the two phase coexistence region. The cause is found not in the generation of additional surface, but in the progressive reduction of the drops radius, and surface, with evaporation.

The complement: a solution to liquid drop finite size effects in phase transitions

The effects of the finite size of a liquid drop undergoing a phase transition are described in terms of the complement, the largest (but mesoscopic) drop representing the liquid in equilibrium with the vapor. Vapor cluster concentrations, pressure, and density from fixed mean density lattice gas (Ising) calculations are explained in terms of the complement generalization of Fishers model. Accounting for this finite size effect is important for extracting the infinite nuclear matter phase diagram from experimental data.

The Hagedorn thermostat

At variance with previous understanding, a system with a Hagedorn-like mass spectrum can sustain the unique temperature T encoded in the spectrum itself. imposes the same temperature to all emitted particles which are then in physical and chemical equilibrium with and with each other. Coexistence between hadronic and partonic phases is thus completely characterized. This may explain the recurring constant physical and chemical temperature observed in several experiments. The near indifference of to fragmentation or coalescence makes this approach relevant to heavy-ion and elementary-particle collisions alike. The equation of state for a gas of systems has been derived.

Compound nuclear decay and the liquid-vapor phase transition: A physical picture

Analyses of multifragmentation in terms of the Fisher droplet model (FDM) and the associated construction of a nuclear phase diagram bring forth the problem of the actual existence of the nuclear vapor phase and the meaning of its associated pressure. We present here a physical picture of fragment production from excited nuclei that solves this problem and establishes the relationship between the FDM and the standard compound nucleus decay rate for rare particles emitted in first-chance decay. The compound thermal emission picture is formally equivalent to an FDM-like equilibrium description and avoids the problem of the vapor while also explaining the observation of Boltzmann-like distribution of emission times. In this picture, a simple Fermi gas thermometric relation is naturally justified and verified in the fragment yields and time scales. Low-energy compound nucleus fragment yields scale according to the FDM and lead to an estimate of the infinite symmetric nuclear matter critical temperature between 18 and 27 MeV depending on the choice of the surface energy coefficient of nuclear matter.

The three-dimensional Ising model: A paradigm of liquid-vapor coexistence in nuclear multifragmentation

Author(s): Mader, Catherine M.; Chappars, Amber; Elliott, James B.; Moretto, Luciano G.; Phair, Larry; Wozniak, Gordon J. | Abstract: Clusters in the three-dimensional Ising model rigorously obey reducibility and thermal scaling up to the critical temperature. The barriers extracted from Arrhenius plots depend on the cluster size as

Standard thermodynamic quantities as determined via models of nuclear multifragmentation

B \propto A^ sigma

Resistible effects of coulomb interaction on nucleus-vapor phase coexistence

wqwhere

Mesoscopy and thermodynamics

\ sigma

Reexamination and extension of the liquid drop model: Correlation between liquid drop parameters and curvature term

is a critical exponent relating the cluster size to the cluster surface. All the Arrhenius plots collapse into a single Fisher-like scaling function indicating liquid-vapor-like phase coexistence and the univarian equilibrium between percolating clusters and finite clusters. The compelling similarity with nuclear multifragmentation is discussed.