Showing papers on "Nuclear matter published in 1977"
TL;DR: In this article, the Hartree and Thomas-Fermi calculations for infinite and semi-infinite symmetric nuclear matter are made for Cubic and quartic scalar meson self-interactions.
931 citations
TL;DR: In this paper, the energy and density dependence of the isoscalar, isovector, and Coulomb components of the complex optical-model potential in infinite nuclear matter, for energies up to 160 MeV.
Abstract: Starting from the Brueckner-Hartree-Fock approximation and Reid's hard core nucleon-nucleon interaction, we calculate and parametrize the energy---and the density---dependence of the isoscalar, isovector, and Coulomb components of the complex optical-model potential in infinite nuclear matter, for energies up to 160 MeV. We then construct the optical-model potential in a finite nucleus. In a first step, we adopt a local density approximation which implies that the value of the complex potential at each point of the nucleus is the same as in a uniform medium with the local density. We compute the corresponding volume integrals per nucleon and mean square radii of the real and of the imaginary parts of the optical-model potential, in particular for protons scattered by $^{12}\mathrm{C}$, $^{16}\mathrm{O}$, $^{27}\mathrm{Al}$, $^{40}\mathrm{Ca}$, $^{58}\mathrm{Ni}$, $^{120}\mathrm{Sn}$, and $^{208}\mathrm{Pb}$. We compare these results with a compilation of empirical values and find that the calculated and experimental volume integrals are in good agreement but that the theoretical mean square radii are too small. We ascribe this discrepancy to the fact that our local density approximation does not include accurately the effect in a nonuniform medium of the range of the effective interaction. We include this range in a semiphenomenological way suggested by the Hartree approximation. With a reasonable value for this range parameter, which is the only one occurring in our work, good agreement is obtained between the theoretical and the empirical values of the volume integrals and mean square radii of the real and, to a lesser extent, of the imaginary parts of the optical-model potential, for mass numbers $12\ensuremath{\le}A\ensuremath{\le}208$ and for energies $E$ up to 160 MeV. Our results are given in analytic form and can thus be used in analyses of experimental data. We also discuss the difference between the optical-model potentials for protons and for neutrons.[NUCLEAR REACTIONS Calculation of the complex optical-model potential for finite nuclei from Reid's hard core interaction; comparison with a compilation of empirical potentials.]
415 citations
TL;DR: In this article, a relativistic quantum many-body theory is applied to the study of high-density matter, where baryons are described as interacting with each other via massive scalar and massive vector meson exchange.
395 citations
TL;DR: In this article, the ground-state energy of a quark gas up to and including effecs of fourth order in the quark-gluon coupling was calculated in terms of a chemical-potential-dependent coupling.
Abstract: We calculate the ground-state energy of a quark gas up to and including effecs of fourth order in the quark-gluon coupling. Renormalization-group techniques are used to rewrite the results of the fourth-order calculation in terms of a chemical-potential-dependent coupling. The chemical-potential-dependent coupling approaches zero at high densities. We argue that at hadronic matter densities a phase transition between quark matter and hadronic matter occurs. We show the existence of this phase transition for a three-color, one-flavor quark gas. We find a close correspondence between the results of quantum chromodynamics at large coupling with no bag constant and quantum chromodynamics at small coupling with a bag constant.
224 citations
TL;DR: In this article, the authors examined the ejection of cold neutron-star matter, and an attempt was made to determine whether the final composition of this matter may be similar to that normally associated with the hot high-neutron-flux r-process.
Abstract: The ejection of cold neutron-star matter is examined, and an attempt is made to determine whether the final composition of this matter may be similar to that normally associated with the hot high-neutron-flux r-process A semiempirical liquid-drop model is used for the nucleus, and the equilibrium composition of the matter is determined by assuming it to be in its absolute ground state at a given density Physical mechanisms operating during the expansion are analyzed, and the composition of the ejected matter is found as a function of its density during expansion The results indicate that it is virtually impossible for deuterium to form, that neutrons can be captured only after beta decay increases the atomic numbers of nuclei, and that no free neutrons can escape It is concluded that neutron-star ejecta can produce heavy neutron-rich nuclei and may produce somewhat heavier nuclei than a standard r-process
219 citations
TL;DR: In this article, the Bethe-Goldstone equation is reduced to a set of coupled differential equations, which are easily solved using the reference spectrum method, and the results for the binding energy/nucleon and the nucleon optical potential are obtained.
156 citations
TL;DR: In this article, the complex nucleon-nucleus optical potential for finite nuclei is calculated from the Hamada-Johnston internucleon interaction and a diagonal representation in coordinate space of the t-matrix is calculated in a nuclear matter approximation.
151 citations
TL;DR: In this article, a method for the measurement of heat conductivity in nuclear matter is formulated in terms of diffusion of heat and the shape of this distribution is calculated based on an asymmetry effect in the angular distribution of evaporation products.
96 citations
TL;DR: In this paper, a variational method for calculating the binding energy of nuclear matter is extended to treat the strong tensor force components of realistic NN potentials, and binding energies of typically 22 MeV per nucleon at saturation densities corresponding to k F ≈ 1.6-1.7 fm −1, are found.
83 citations
TL;DR: In this paper, the authors investigated how the mass operator for symmetric and uncharged nuclear matter is modified in the presence of a Coulomb field and of neutron excess, and they used a local density approximation to construct the optical-model potential in a finite nucleus.
Abstract: We first investigate how the mass operator for symmetric and uncharged nuclear matter is modified in the presence of a Coulomb field and of neutron excess. Detailed calculations are performed with Reid's hard-core nucleon-nucleon interaction. They are carried out in the framework of the Brueckner-Hartree-Fock approximation, although some higher-order contributions to the low-density expansion of the mass operator are also considered. We relate the mass operator to the optical-model potential. We then use a local density approximation to construct the optical-model potential in a finite nucleus. We find that the half-depth radius of the isoscalar part of the calculated optical-model potential has the form ${r}_{V}{A}^{\frac{1}{3}}$, where $A$ denotes the mass number. Since this property has always been assumed in the phenomenological analysis of the scattering data, a meaningful comparison is possible between our theoretical results for the symmetry and for the Coulomb components of the optical-model potential on the one hand, and the empirical values of these quantities as determined from the analysis of proton and neutron elastic scattering data or of direct charge exchange reactions on the other hand. The calculated depth of the symmetry potential is 11.5 MeV, but its range is larger than that of the isoscalar potential. The calculated value of the so-called Coulomb correction is larger than the one that is assumed in most empirical analyses. The combined effect of these features yields good overall agreement between the calculated and the empirical dependence on neutron excess of the optical-model potential.NUCLEAR REACTIONS Calculation of the symmetry and Coulomb components of the optical-model potential from Reid's hard-core nucleon-nucleon interaction.
72 citations
TL;DR: In this paper, a momentum-space nucleon-nucleon potential in the OBE frame is presented where part of the phenomenological σ-contribution describing the intermediate range attraction is replaced by the twice-iterated pion-exchange potentials which couple the NN channel with the NΔ(1236) and ΔΔ channels.
TL;DR: In this paper, a theory for nuclear collective motion in the long mean-free-path limit is developed for large leptodermous systems, characterized by mass and dissipation kernels coupling the velocity at different points on the surface.
TL;DR: In this article, the techniques of linear response theory are applied to nuclear one-body dissipation, and the rate of energy dissipation is characterized by a kernel, γ, coupling the motion at different points in the nuclear surface.
TL;DR: In this article, a refined version of the compressible liquid drop model of the nucleus introduced by Baym, Bethe, and Pethick has been developed, and by fitting the model to the binding and Coulomb energies of heavy nuclei, they redetermine phenomenologically the bulk and surface properties of symmetric nuclear matter.
TL;DR: In this paper, the properties of the collective modes in nuclear matter in four available longitudinal channels were studied, and the authors selected tour different effective interactions, including the finite-range interaction with density-dependent part Dl.
TL;DR: In this article, a statistical model is presented which describes light fragment formation in high energy nuclear collisions, and data from 20Ne+U collisions at 250 and 400 MeV/nucleon indicate statistical coalescence of a nuclear fireball occurs at temperatures of 30-40 MeV.
TL;DR: A spin independent Glauber theory analysis allowed the extraction of nuclear matter densities for these targets in this paper, where the isotopically enriched 58,60,62,64 Ni isotopes were studied.
TL;DR: In this article, the authors compare and contrast the results obtained in a hydrodynamical calculation and in the TDHF calculations of Bonche, Koonin and Negele for the collision of two slabs of nuclear matter.
TL;DR: In this paper, a quantitative parameter-free description of the data by Binkley et al. on the lepton-pair production on nuclei is given, and quark counting rules for the A -dependences of the fragmentation spectra are proposed.
TL;DR: In this paper, the choice of the auxiliary potential U which is introduced in the low density expansion of the mass operator M (k, w ) is discussed, which is related to the analytical properties of M ( k, w) in the complex w-plane and takes due account of momentum conservation in the intermediate states appearing in the diagrams associated with M(k, w ).
TL;DR: In this paper, the energy of nuclear matter in correspondence to a semirealistic nucleon-nucleon interaction was calculated within the framework of the Jastrow variational approach with state dependent correlation functions.
TL;DR: In this article, the authors extracted the 40Ca matter density from an analysis of the elastic scattering of 166 MeV alpha particles using an optical potential whose real part was evaluated by folding the matter density with a nucleon-alpha interaction.
Abstract: The authors propose to extract, independently of any nuclear model, the 40Ca matter density from an analysis of the elastic scattering of 166 MeV alpha particles. The scattering is described using an optical potential whose real part is evaluated by folding the matter density with a nucleon-alpha interaction. Following the procedure proposed by Sick whose amplitudes are deduced in fitting, via a chi 2 minimization, the experimental cross section data. This method determines the envelope of densities for different parameters of gaussians: width, spacing. The envelope of the moments of these densities are presented and the root-mean-square radius is extracted. They conclude that only the nuclear surface is well studied by the alpha particle scattering.
01 Jan 1977
TL;DR: In this paper, forbidden decay modes of one-and two-electron ions, fine structure of helium, long range forces in quantum theory, simulated Compton scattering and related phenomena, field-theory on the light-cone and the Parton model, deep inelastic scattering, deep-inelastic processes, interactions of photons with nuclear matter, the hadronic properties of the photon, radiative corrections to electron form factors, Eikonal mechanisms at high energy, and unified theories of weak and electromagnetic interactions.
Abstract: Topics covered include: forbidden decay modes of one- and two-electron ions; fine structure of helium; long range forces in quantum theory; simulated Compton scattering and related phenomena; field-theory on the light-cone and the Parton model; deep inelastic scattering; deep inelastic processes; interactions of photons with nuclear matter; the hadronic properties of the photon; radiative corrections to electron form factors; Eikonal mechanisms at high energy; the quantum mechanics of chiral theories; and unified theories of weak and electromagnetic interactions. (GHT)
TL;DR: In this article, three independent evaluations of the ground-state energy of a simple model of nuclear matter are compared and the potential chosen is central, consisting of a state-independent hard core surrounded by a spin-dependent Serber square well with parameters adjusted to produce a fit of the low-energy two-nucleon data.
TL;DR: In this article, three models, based on the mean field and sigma models, were considered, all of which fit the saturation properties and the symmetry energy of nuclear matter, and none of the models yields an abnormal state of neutron star matter at supemuclear density even when pion condensation is taken into account.
TL;DR: In this paper, the three-body force contributions in nuclear matter usually generated through a πN scattering amplitude dominated by the Δ(1236) resonance, are treated as a three-nucleon cluster, in which one of the nucleons becomes, in an intermediate state, a Δ-resonance.
TL;DR: In this paper, the binding energy per nucleon in nuclear matter was calculated using the three-nucleon potentials obtained with the two nucleon OBEP of Ueda and Green (UGI), and the bounding energy was found to be 0.4, 4.3 and −1.4 fm −1 for the net contributions from the three n-clusters due to π, S and ω, respectively.
TL;DR: In this article, the binding energy of nuclear matter has been analyzed in two-and three-body cluster approximation as a function of the separation distance at which the central and tensor correlations heal smoothly.
TL;DR: In this paper, a phenomenological ansatz for the binding energy of finite nuclear matter is made; this permits a description of density isomers, and it is assumed to have a second minimum at higher densities caused by a phase transition of the nuclear matter.
Abstract: A phenomenological ansatz for the binding energy of finite nuclear matter is made; this permits a description of density isomers. The binding energy of infinite nuclear matter is assumed to have a second minimum at higher densities caused by a phase transition of the nuclear matter. By minimization of the energy, density distributions for normal and density-isomeric nuclei are calculated and their dependence upon the parameters of the model is investigated.