Showing papers on "Nuclear matter published in 1983"
TL;DR: In this paper, it is suggested that in order to approximate more complicated kinds of short-range order, the dimensionality should be regarded as a continuous variable ranging from d = 3 (spheres) to d = 1 (planes).
Abstract: It is found that just below nuclear saturation density more stable forms of dense matter exist than the near-spherical nuclei or bubbles customarily assumed. Because of the large effect of the Coulomb lattice energy, cylindrical and planar geometries can occur, both as nuclei and as bubbles. It is suggested that in order to approximate more complicated kinds of short-range order, the dimensionality should be regarded as a continuous variable ranging from d = 3 (spheres) to d = 1 (planes). The dependence of d on density is illustrated, and its dependence on nuclear models discussed.
469 citations
TL;DR: In this paper, the results of variational calculations of 3 H, 3 He, 4 He and nuclear matter with the Urbana v 14 two-nucleon interaction and realistic models of the TNI were reported.
312 citations
TL;DR: In this paper, the binding energy and saturation properties of nuclear matter, the density and momentum transfer dependence of the effective force in nuclei and the parameters of a relativistic optical model are discussed.
183 citations
TL;DR: In this article, the collective effects due to nuclear matter compression were studied in the framework of the cascade model, where heavy ion-induced reactions as opposed to light ion induced reactions were discussed.
170 citations
TL;DR: In this paper, laboratory observations with the latest generation of nuclear accelerators are used to infer the surface tension of the liquid-gas interface in nuclear matter, an essential ingredient of the equation of state for which a reliable theoretical model is not available.
Abstract: Every self-bound Fermi liquid will exhibit a liquid–gas phase equilibrium at low temperatures, because the pressure is positive at low densities due to the kinetic energy of degeneracy, and falls to zero again at the equilibrium density. Nuclear matter is seldom found under conditions of two-phase equilibrium, however: in usual nuclear reactions, a heated (‘compound’) nucleus is produced out of equilibrium with its surroundings, which are at a much lower temperature. The most familiar example of a two-phase equilibrium occurs in the crust of neutron stars inside the neutron-drip line1, at temperatures of less than an MeV. In supernovas, in the crucial moments when the implosion is reversed to an explosion, densities comparable to those of neutron stars may be attained with associated temperatures of 5 to 10 MeV. An accurate knowledge of the properties of nuclear matter under these conditions is essential to the understanding of supernova dynamics2. This communication shows how laboratory observations with the latest generation of nuclear accelerators can be used to infer the surface tension of the liquid–gas interface in nuclear matter–an essential ingredient of the equation of state for which a reliable theoretical model is not available.
164 citations
TL;DR: In this paper, the properties of symmetric nuclear matter are investigated in a phenomenological non-linear relativistic field theory of nuclear matter, and a mean field approximation is made. But the importance of non-Yukawa type nuclear interactions is discussed.
134 citations
TL;DR: In this article, the relativistic Hartree-Fock (HF) equations for an infinite system of mesons and baryons were derived based on a diagrammatic approach and Dyson's equation for the baryon propagator.
124 citations
TL;DR: In this article, the thermodynamic properties at finite temperatures of the plane interface between two phases of nuclear matter in equilibrium are examined theoretically, and explored numerically, and approximate analytic fits are given to the χ i (proton fraction on the dense-matter side) dependence of the critical temperature, and to the T and χ n dependences of the surface thermodynamic potentials, the density of surface neutrons, the surface entropy and the neutron and proton chemical potentials at phase equilibrium.
91 citations
TL;DR: In this article, it was shown that one can reproduce the observed binding energy and density of nuclear matter within experimental precision in an area characterized by a line in the coupling-constant plane.
Abstract: Studying Walecka's mean-field theory we find that one can reproduce the observed binding energy and density of nuclear matter within experimental precision in an area characterized by a line in the coupling-constant plane. A part of this line defines systems which exhibit a phase transition around T/sub c/approx.200 MeV for zero baryon density. The rest corresponds to such systems where the phase transition is absent; in that case a peak appears in the specific heat around Tapprox.200 MeV. We interpret these results as indicating that the hadron phase of nuclear matter alone indicates the occurrence of an abrupt change in the bulk properties around rho/sub V/approx.0 and Tapprox.200 MeV.
87 citations
TL;DR: In this article, a self-consistent ladder Hartree-Fock approximation is derived in order to achieve a simultaneous treatment of free nucleons, douterons and higher clusters.
79 citations
TL;DR: In this paper, the number operator for excess pions present in nuclei due to the pion exchange forces between nucleons was constructed using variational wave functions obtained from a realistic Hamiltonian.
Abstract: The authors construct, in the static potential approximation, the number operator for excess pions present in nuclei due to the pion-exchange forces between nucleons. Expectation values are calculated with use of variational wave functions obtained from a realistic Hamiltonian. Results are presented for systems ranging from the deuteron to nuclear matter: For example $^{56}\mathrm{Fe}$ is estimated to have \ensuremath{\sim}7 extra pions, over and above the pion clouds associated with the individual nucleons.
TL;DR: In this article, a vector meson field via the Higgs mechanism was introduced to construct a chiral theory of pions which leads to a saturating nuclear matter equation of state.
TL;DR: In this article, the relative abundances of hadronic particles produced in highly excited nuclear matter were computed as functions of temperature and baryo-chemical potential. And the results were quantitatively compatible with present experimental data obtained in nuclear collisions.
TL;DR: In this paper, a simple outline of correlated basis perturbation theory is given to study the optical potential of nucleons in nuclear matter and the second-order CBF correction to the binding energy is calculated.
TL;DR: In this paper, a universal effective NN interaction of the Skyrme type has been proposed which is suitable for both ground and excited states in nuclei throughout the nuclear mass table.
TL;DR: In this paper, the authors focus on central nuclear collisions in the energy range 20 −400 MeV/n and focus on the importance of medium mass fragment production for this goal.
TL;DR: In this article, different microscopic models for elastic scattering of neutrons from /sup 54,56/Fe have been analyzed both in terms of the standard phenomenological optical model, and in the framework of two different microscopic model based upon nuclear matter calculations using realistic nucleon-nucleon interactions and a local density approximation.
Abstract: Differential cross sections for elastic scattering of neutrons from /sup 54,56/Fe have been measured at several energies in the 20--26 MeV region. The data have been analyzed both in terms of the standard phenomenological optical model, and in the framework of two different microscopic models based upon nuclear matter calculations using realistic nucleon-nucleon interactions and a local density approximation. Isospin consistency of the microscopic-model calculations was also tested by analyzing proton elastic differential cross section data in the same energy region, as well as both proton and neutron elastic analyzing power data. The microscopic calculations yield quite reasonable agreement with the data, even though they contain no free geometrical parameters. The quality of the results for the analyzing power data is particularly impressive, indicating that the very simple, density- and energy-independent spin-orbit force used in the calculations is sufficient. The differences between the various models are clarified by examining the momentum-space representations of the potentials.
TL;DR: In this paper, the effects of the induced interactions on the particle-hole interaction in nuclear matter are investigated to all orders, starting from Brueckner's G -matrix.
TL;DR: In this article, a method is developed which allows the determination of a local G-operator, i.e. G without the bare interaction V, in terms of meson-exchange-type interactions.
TL;DR: Using a version of the chiral invariant σ-model, it was shown that many-body forces can eliminate the discrepancy between calculated and empirical values of the binding energy and equilibrium density of nuclear matter.
TL;DR: In this article, the energy dissipation in slow collective nuclear motion is viewed as a combined effect of a diabatic production of particle-hole excitations, leading to a conservative storage of collective energy, and a subsequent equilibration due to residual two-body collisions.
TL;DR: In this article, the liquid-vapor phase transition in nuclear systems at temperatures below the critical one (T ≲ 20 MeV) is studied by calculating the corresponding barrier penetrabilities.
TL;DR: In this article, it was suggested that manybody forces of the form suggested by either conventional or chiral pictures are responsible for the remaining discrepancy and to adjust parameters in such model many-body forces to restore agreement between theory and experiment.
Abstract: Recent years have brought considerable improvement in the quality of both diagrammatic and variational many-body techniques. There appears to be general agreement that realistic NN potentials give a reasonable binding energy but an equilibrium density that is some 75% larger than the empirical value. Both conventional and chiral models of genuine manybody forces offer mechanisms for removing this discrepancy with each providing a simple picture for the required additional attraction for /rho/ < /rho//sub 0/. Neither approach is presently able to make a priori estimates of the magnitude of this effect with the delicacy required by the nuclear matter problem. Nor is it clear how to merge these pictures. We should not anticipate quick answers to these questions. One suitable interim strategy is to assume that many-body forces of the form suggested by either conventional or chiral pictures are responsible for the remaining discrepancy and to adjust parameters in such model many-body forces to restore agreement between theory and experiment. This might seem to be a summary dismissal of the standard nuclear matter problem. It should rather be regarded as revealing the next and richer layer of the nuclear matter problem.
TL;DR: In this article, a time-dependent shell model is introduced to simultaneously treat coherent and incoherent aspects of large-amplitude collective nuclear motion. But the model is not suitable for the case of large numbers of nucleons.
TL;DR: In this article, the discrepancy between standard intranuclear cascade model predictions and experimental data for the pion multiplicity in central nucleus-nucleus collisions has been interpreted as a manifestation of compression effects.
TL;DR: In this article, a nonlinear relativistic mean field theory was proposed to study the nuclear surface properties, and the strength of the required parameters is determined from the binding energy and density of nuclear matter and the effective nucleon mass.
TL;DR: In this paper, the application of entropy to composite particle production in nucleus-nucleus collisions is reviewed and it is shown that more entropy is generated in high energy nuclear collisions than is predicted from bulk dynamics, due to the surfaces which are effectively quite thick.
TL;DR: In this article, a simple equation of state for supernovae was derived and compared with more detailed equations of state, and the simplified one was found to represent well all important features.
TL;DR: In this paper, a high-energy proton (E> 5GeV) drills a hole through the target nucleus, the hole expands, bonds break and a few pieces of nuclear matter result.