Norman K. Glendenning

Determination of Y40 and Y60 components in the shapes of rare earth nuclei

Abstract Differential cross sections for 50 MeV alpha particles of members of the ground state rotational band up to the 6 + or 8 + state were measured in a number of even nuclei of the rare earth region. The data were analyzed under the assumption of a perfect rotor description for the nucleus and a deformed optical interaction between alpha and nucleus by solving the resulting coupled equations. Higher order components Y 4 and Y 6 in the nuclear shapes were determined with precision. A systematic variation of B 4 from positive values in the light rare earths to negative values in the heavy ones is established.

Signal of Quark Deconfinement in the Timing Structure of Pulsar Spin-Down

(May, 12, 1997)The conversion of nuclear matter to quark matter in thecore of a rotating neutron star alters its moment of inertia.Hence the epoch over which conversion takes place will be sig-naled in the spin-down characteristics of pulsars. We find thatan observable called the braking index should be easily mea-surable during the transition epoch and can have a value farremoved (by orders of magnitude) from the canonical value ofthree expected for magnetic dipole radiation, and may haveeither sign. The duration of the transition epoch is governedby the slow loss of angular momentum to radiation and isfurther prolonged by the reduction in the moment of inertiacaused by the phase change which can even introduce an eraof spin-up. We estimate that about one in a hundred pulsarsmay be passing through this phase. The phenomenon is anal-ogous to “bachbending” observed in the moment of inertia ofrotating nuclei observed in the 1970’s, which also signaled achange in internal structure with changing spin.97.60Lf, 97.60.Gb, 97.10.Cv

First order kaon condensate

First order Bose condensation in asymmetric nuclear matter and in neutron stars is studied, with particular reference to kaon condensation. We demonstrate explicitly why the Maxwell construction fails to assure equilibrium in multicomponent substances. Gibbs conditions and conservation laws require that for phase equilibrium, the charge density must have opposite sign in the two phases of isospin asymmetric nuclear matter. The mixed phase will therefore form a Coulomb lattice with the rare phase occupying lattice sites in the dominant phase. Moreover, the kaon condensed phase differs from the normal phase, not by the mere presence of kaons in the first, but also by a difference in the nucleon effective masses. The mixed phase region, which occupies a large radial extent amounting to some kilometers in our model neutron stars, is thus highly heterogeneous. It should be particularly interesting in connection with the pulsar glitch phenomenon as well as transport properties. {copyright} {ital 1999} {ital The American Physical Society}

Kaon condensation and dynamical nucleons in neutron stars

We discuss the nature of the kaon condensation phase transition. We find several features which, if kaons condense in neutron stars, are not only remarkable, but must surely effect such properties as superfluidity and transport properties, which in turn are relevant to the glitch phenomenon and cooling rates of neutron stars. The mixed phase, because of the extensive pressure range that it spans, will occupy a broad radial extent in a neutron star. This region is permeated with microscopic drops (and other configurations) located at lattice sites of one phase immersed in the background of the other phase. The electric charge on drops is opposite to that of the background phase {\sl and} nucleons have a mass approximately a factor two different depending on whether they are in the drops or the background phase. A large part of the stellar interior has this highly non-homogeneous structure.

Phase transitions and crystalline structures in neutron star cores

Abstract The mixed phase of a fully equilibrated nuclear system that is asymmetric in isospin (i.e. in charge) will develop a geometrical structure of the rarer phase immersed in the dominant one. This happens because the isospin asymmetry energy will exploit the degree of freedom available to a system of more than one independent component (or conserved charge) by rearranging the proportion of charge to baryon number between the two equilibrium phases so as to lower the energy; that is, to effectively reduce the isospin asymmetry in the normal nuclear phase. Consequently, the two phases will have opposite charge; competition between Coulomb and surface energy will be resolved by formation of a Coulomb lattice of the rarer phase situated at sites in the dominant phase. The geometric form, size, and spacing of the phase occupying the lattice sites will depend on the pressure or density of matter. Thus, a neutron star containing a mixed phase region of whatever kind, will have a varying geometric structure of one phase embedded in the other. This is expected to effect transport properties of the star as well as to effect the glitch behavior of pulsars that contain a mixed phase region. We study in particular, the quark deconfinement and kaon condensation phase transitions as examples of this general phenomenon.

The hyperon composition of neutron stars

Abstract Neutron stars are studied in the framework of relativistic interacting field theory of nucleons, hyperons, and mesons. A large component of strange baryons is found, and in the interior the neutron population is minor.

The two-nucleon stripping reaction

Abstract Expressions for the angular distribution of the (α, d) reaction are derived. Explicit coupling schemes for even, odd-mass and odd target nuclei in the j - j limit are used to define the nuclear structure factors.

Thermal Evolution of Compact Stars

Abstract A collection of modern, field-theoretical equations of state is applied to the investigation of cooling properties of compact stars. These comprise neutron stars as well as hypothetical strange-matter stars, made up of absolutely stable 3-flavor strange-quark matter. Various uncertainties in the behavior of matter at supernuclear densities, e.g., hyperonic degrees of freedom, behavior of coupling strengths in matter, pion and meson condensation, superfluidity, transition to quark matter, absolute stability of strange-quark matter, and last but not least the many-body technique itself are tested against the body of observed cooling data.

The giant E1 resonance for deformed nuclei

Abstract The random-phase approximation has been applied in particular to treat the giant E1 resonance of the deformed nucleus Mg 24 . Two well separated peaks are predicted on the basis of reasonable force parameters. The backward-going graphs are found not to affect significantly the positions of the 1 − states or the relative distribution of the oscillator strength. On the other hand the Thomas-Kuhn-Reiche sum is diminished for the case of a Ferrell-Visscher force by a magnitude of up to 30% by the inclusion of ground state correlations. The violation of the TKR sum rule encountered in the shell-model calculations is thus reduced considerably.

Confirmation of strong second order processes in (p, t) reactions on deformed nuclei

Abstract The (p, t) reaction on deformed nuclei has been computed with the inclusion of indirect transitions that go through intermediate rotational states. The indirect transitions are almost as large as the direct for the 2 + state and their inclusion is essential to bring about agreement with the shape and magnitude of the differential cross-section.