117043476
Superfluidity of {Lambda} hyperons in neutron stars
We study the {sup 1}S{sub 0} superfluidity of {Lambda} hyperons in neutron star matter and neutron stars. We use the relativistic mean field (RMF) theory to calculate the properties of neutron star matter. In the RMF approach, the meson-hyperon couplings are constrained by reasonable hyperon potentials that include the updated information from recent developments in hypernuclear physics. To examine the {sup 1}S{sub 0} pairing gap of {Lambda} hyperons, we employ several {Lambda}{Lambda} interactions based on the Nijmegen models and used in double-{Lambda} hypernuclei studies. It is found that the maximal pairing gap obtained is a few tenths of a MeV. The magnitude and the density region of the pairing gap are dependent on the {Lambda}{Lambda} interaction and the treatment of neutron star matter. We calculate neutron star properties and find that whether the {sup 1}S{sub 0} superfluidity of {Lambda} hyperons exists in the core of neutron stars mainly depends on the {Lambda}{Lambda} interaction used.
122623840
Coulomb explosions and stopping of molecular ions channeled through carbon nanotubes
We study Coulomb explosions of fast H{sub 2}{sup +} molecules under the channeling conditions through a single-wall carbon nanotube by solving the classical equations of motion for the fragment ions, involving both the repulsive continuum potential of the nanotube wall and the dynamically screened Coulomb repulsion between the two ions. Dynamic polarization of the nanotube electrons, described by a two-dimensional hydrodynamic model, gives rise to the correlated energy losses, a wakelike interaction between the fragment ions, as well as the dynamical image force on each ion. The explosion dynamics is dominated by the bare Coulomb repulsion and it mostly proceeds in the longitudinal direction, accompanied with the radially constrained oscillations of the fragment ions. Strong vicinage effects are found in both the molecule self-energy and its stopping power in the early stages of explosions, but they quickly diminish with the increasing dwell time in a manner which depends on the impact molecule speed and its axis orientation.
55106891
Dynamic interactions of fast ions with carbon nanotubes
We used the hydrodynamic model to describe the dielectric response of a multi-walled carbon nanotube to a fast point charge moving paraxially, either inside or outside the nanotube. Calculations are performed for a two-walled nanotube, giving rise to a splitting of the plasmon frequencies due to the interaction between the electron fluids on the two cylinders. The dependences of the projectile stopping power and the self-energy (image potential) on the velocity and the distance from the nanotube axis show interesting features when the projectile velocity matches the phase velocity of the plasmon mode with a quasi-linear dispersion.
54686029
Dynamic polarization effects in ion channeling through single-wall carbon nanotubes
Ion channeling through a single-wall carbon nanotube is simulated by solving Newton’s equations for ion motion at intermediate energies, under the action of both the surface-atom repulsive forces and the polarization forces due to the dynamic perturbation of the nanotube electrons. The atomic repulsion is described by a continuum potential based on the Thomas-Fermi-Moliere model, whereas the dynamic polarization of the nanotube electrons is described by a two-dimensional hydrodynamic model, giving rise to the transverse dynamic image force and the longitudinal stopping force. In the absence of centrifugal forces, a balance between the image force and the atomic repulsion is found to give rise to ion trajectories which oscillate over peripheral radial regions in the nanotube, provided the ion impact position is not too close to the nanotube wall, the impact angle is sufficiently small, and the incident speed is not too high. Otherwise, the ion is found to oscillate between the nanotube walls, passing over a local maximum of the potential in the center of the nanotube, which results from the image interaction. The full statistical analysis of 10 3 ion trajectories has been made to further demonstrate the actual effect of dynamic polarization on the ion channeling.
98624315
Dynamic interactions of fast ions with multiwalled carbon nanotubes
Abstract We use a two-fluid hydrodynamic model to describe the dielectric response of the σ and π electron systems on a multiwalled carbon nanotube consisting of up to several tens of concentric cylindrical shells. In particular, we evaluate the stopping power and the dynamical image potential for ions moving parallel to the nanotube axis. It is found that both quantities are profoundly affected by the increasing number of nanotube shells, as a consequence of the rich plasmon spectra developed due to the inter- and intra-shell electrostatic interactions between the electron systems.
119981129
Interactions of fast ions with carbon nanotubes: Self-energy and stopping power
The interactions of charged particles with carbon nanotubes are studied by means of the linearized hydrodynamic theory for electronic excitations on the nanotube surface. General expressions are derived for the induced potential, the self-energy, and the stopping power for a charged particle moving paraxially in a nanotube. Numerical results are obtained showing the influence of the damping factor, the nanotube radius, and the particle position on its self-energy and the stopping power. Results for stopping power in the linearized hydrodynamic model are compared with those obtained by means of the dielectric formalism in random-phase approximation, showing a close agreement between the two approaches for high speeds of charged particles.
118671314
Cosmic constraint to DGP brane model: Geometrical and dynamical perspectives
In this paper, the Dvali-Gabadadze-Porrati (DGP) brane model is confronted by current cosmic observational data sets from geometrical and dynamical perspectives. On the geometrical side, the recently released Union2 557 of type Ia supernovae (SN Ia), the baryon acoustic oscillation from the Sloan Digital Sky Survey and the Two Degree Galaxy Redshift Survey (transverse and radial to line-of-sight data points), the cosmic microwave background measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations [shift parameters R, l{sub a}(z{sub *}) and redshift at the last scatter surface z{sub *}], ages of high redshifts galaxies, i.e., the lookback time and the high redshift gamma ray bursts are used. On the dynamical side, data points about the growth function of matter linear perturbations are used. Using the same data set combination, we also constrain the flat {Lambda}CDM model as a comparison. The results show that current geometrical and dynamical observational data sets much favor the flat {Lambda}CDM model and the departure from it is above 4{sigma}(6{sigma}) for the spatially flat DGP model with (without) SN systematic errors. The consistence of growth function data points is checked in terms of a relative departure of redshift-distance relation.
120127236
Systematic study of tensor effects in shell evolution
In the framework of the Hartree-Fock-Bogoliubov approach with the Skyrme interactions SLy5, SLy5+T, SLy5+T{sub w}, and several sets of the TIJ parametrizations (Skyrme effective interaction parametrizations including the tensor terms), the effect of the tensor force on the shell evolution at Z,N=8, 20, and 28 is investigated. It is shown that the evolution of the gap (defined as the energy difference between the last occupied and first unoccupied single-particle orbits) with SLy5+T is similar to that with SLy5+T{sub w}, and the gap values with SLy5+T are smaller than those with SLy5+T{sub w} in the cases of Z,N=8, 20. At Z, N = 28, the gap values with SLy5 are smaller than those with SLy5+T and larger than those with SLy5+T{sub w}. To understand these features, we analyze the spin-orbit potentials with and without the tensor contributions and the radial wave functions of relevant orbits. Meanwhile, we find that the deviation of the calculated gaps with SLy5+T{sub w} from the experimental ones is larger than that with SLy5+T. This indicates that SLy5+T{sub w} is not suitable for investigating the properties of the ground-state gap evolution. Finally, it is seen that the gap evolutions with different sets of the TIJ parametrizations aremore » similar to each other except for the ones with T22, and there is almost no difference between the tensor effect in gap evolution with the perturbative method and the one with the complete fitting method.« less
118163168
Three-dimensional two-layer outer gap model: the third peak of vela pulsar
We extend the two-dimensional two-layer outer gap model to a three-dimensional geometry and use it to study the high-energy emission of the Vela pulsar. We apply this three-dimensional two-layer model to the Vela pulsar and compare the model light curves, the phase-averaged spectrum and the phase-resolved spectra with the recent Fermi observations, which also reveals the existence of the third peak between two main peaks. The phase position of the third peak moves with the photon energy, which cannot be explained by the geometry of magnetic field structure and the caustic effect of the photon propagation. We suggest that the existence of the third peak and its energy dependent movement results from the azimuthal structure of the outer gap.
209869998
Observation of the decay psi(2S) ---> K*(892)anti-K + c.c.
4367737
Experimental investigation of geologically produced antineutrinos with KamLAND
The detection of electron antineutrinos produced by natural radioactivity in the Earth could yield important geophysical information. The Kamioka liquid scintillator antineutrino detector (KamLAND) has the sensitivity to detect electron antineutrinos produced by the decay of 238U and 232Th within the Earth. Earth composition models suggest that the radiogenic power from these isotope decays is 16 TW, approximately half of the total measured heat dissipation rate from the Earth. Here we present results from a search for geoneutrinos with KamLAND. Assuming a Th/U mass concentration ratio of 3.9, the 90 per cent confidence interval for the total number of geoneutrinos detected is 4.5 to 54.2. This result is consistent with the central value of 19 predicted by geophysical models. Although our present data have limited statistical power, they nevertheless provide by direct means an upper limit (60 TW) for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.