5,070 research outputs found
Strange particle production in a single-freeze-out model
The transverse-momentum spectra and elliptic flow of strange particles are
calculated in the framework of the single-freeze-out model and compared with
the recent RHIC data. An overall very good agreement between the model
predictions and the data is obtained.Comment: talk presented by WF during the VIIIth Int. Conf. on Strangeness in
Quark Matter, Cape Town, Sept. 15-20, 200
J08069+1527: A newly discovered high amplitude, hybrid subdwarf B pulsator
We present our discovery of a new hybrid pulsating subdwarf B star,
J08069+1527. The effective temperature and surface gravity of 28,500400\,K
and 5.370.04\,dex, respectively, place this object inside the instability
strip and also among other pulsating hot subdwarfs of a hybrid nature, right
next to another fascinating star: Balloon\,090100001. From this proximity, we
anticipated this star could pulsate in both high and low frequency modes.
Indeed, our analysis of photometric data confirmed our prediction. We detected
two peaks in the high frequency region and two other peaks at low frequencies.
In addition, the amplitude of the dominant mode is very high and comparable to
the dominant peaks in other hybrid subdwarf B stars. Since this star is bright,
we performed time-series low resolution spectroscopy. Despite a low
signal-to-noise (S/N) ratio, we were able to detect the main peak from these
data. All our results strongly indicate that J08069+1527 is a high amplitude
pulsating hot subdwarf B star of hybrid nature. By analogy to the other
pulsating sdB star, we judge that the dominant mode we detected here has radial
nature. Future stellar modeling should provide us with quite good constrains as
p- and g-modes presented in this star are driven in different parts of its
interior.Comment: 7 pages, 10 figures, accepted for publication in MNRA
Nuclear Periphery in Mean-Field Models
The halo factor is one of the experimental data which describes a
distribution of neutrons in nuclear periphery. In the presented paper we use
Skyrme-Hartree (SH) and the Relativistic Mean Field (RMF) models and we
calculate the neutron excess factor defined in the paper which
differs slightly from halo factor . The results of the
calculations are compared to the measured data.Comment: Proceedings of the Xth Nuclear Physics Workshop, Maria and Pierre
Curie, Kazimierz Dolny, Poland, Sept 24-28, 2003; LaTex, 4 pages, 3 figure
Title: Quadrupole collective inertia in nuclear fission: cranking approximation
Collective mass tensor derived from the cranking approximation to the
adiabatic time-dependent Hartree-Fock-Bogoliubov (ATDHFB) approach is compared
with that obtained in the Gaussian Overlap Approximation (GOA) to the generator
coordinate method. Illustrative calculations are carried out for
one-dimensional quadrupole fission pathways in 256Fm. It is shown that the
collective mass exhibits strong variations with the quadrupole collective
coordinate. These variations are related to the changes in the intrinsic shell
structure. The differences between collective inertia obtained in cranking and
perturbative cranking approximations to ATDHFB, and within GOA, are discussed.Comment: 9 pages, RevTeX, 4 figure
Collective inertia and fission barriers within the Skyrme-Hartree-Fock theory
Spontaneous fission barriers, quadrupole inertia, and zero-point
quadrupole-energy corrections are calculated for 252,256,258Fm in the framework
of the self-consistent Skyrme-Hartree-Fock+BCS theory. Two ways of computing
dynamical inertia are employed: the Gaussian Overlap Approximation to the
Generator Coordinate Method and cranking ansatz. The Skyrme results are
compared with those of the Gogny-Hartree-Fock-Bogolyubov model.Comment: 9 pages, 6 figures, missing factor of 2 found, figures corrected, to
be published in International Journal of Modern Physics
Multichannel operation of an integrated acousto-optic wavelength routing switch for WDM systems
Polarization independent acousto-optic tunable filters (PIAOTF's) can operate as transparent wavelength-selective crossconnects to route signals in wavelength division multiplexed optical networks. In this paper, a new low power PIAOTF is characterized as a switch in multiwavelength operation, using four equally spaced lightwave signals with wavelengths between 1546 nm and 1558 nm. Interchannel interference due to sidelobe excitation is lower than -11 dB for single wavelength switching and is equal to -6 dB in the extreme case of simultaneous switching of all wavelength channels. Sources of interport and interchannel crosstalk for single and multiple wavelength switching are identified
How Effectively Are We Managing Innovation?
The writer\u27s observe that top management\u27s stated commitment to innovation has yet to be successfully infused into many organizations
The applicability of physical optics in the millimetre and sub-millimetre spectral region. Part II: Application to a three-component model of ice cloud and its evaluation against the bulk single-scattering properties of various other aggregate models
The bulk single-scattering properties of various randomly oriented aggregate ice crystal models are com- pared and contrasted at a number of frequencies between 89 and 874 GHz. The model ice particles consist of the ten-branched plate aggregate, five-branched plate aggregate, eight-branched hexagonal aggregate, Voronoi ice aggregate, six-branched hollow bullet rosette, hexagonal column of aspect ratio unity, and the ten-branched hexagonal aggregate. The bulk single-scattering properties of the latter two ice particle models have been calculated using the light scattering methods described in Part I, which represent the two most extreme members of an ensemble model of cirrus ice crystals. In Part I, it was shown that the method of physical optics could be combined with the T-matrix at a size parameter of about 18 to compute the bulk integral ice optical properties and the phase function in the microwave to sufficient ac- curacy to be of practical value. Here, the bulk single-scattering properties predicted by the two ensemble model members and the Voronoi model are shown to generally bound those of all other models at fre- quencies between 89 and 874 GHz, thus representing a three-component model of ice cloud that can be generally applied to the microwave, rather than using many differing ice particle models. Moreover, the Voronoi model and hollow bullet rosette scatter similarly to each other in the microwave. Furthermore, from the various comparisons, the importance of assumed shapes of the particle size distribution as well as cm-sized ice aggregates is demonstrated.Peer reviewedFinal Accepted Versio
Isospin Dynamics in Peripheral Heavy Ion Collisions at Fermi Energies
We present a detailed study of isospin dynamics in peripheral collisions at
Fermi energies. We consider symmetric and mixed collisions of (124,112)Sn
isotopes at 35 and 50 AMeV to study the isospin transport between the different
reaction components (residues, gas and possibly intermediate mass fragments)
and, in particular, the charge equilibration in the mixed system. We evaluate
the effects of drift terms due to asymmetry and density gradients, which are
directly related to the poorly known value and slope of the symmetry energy
below saturation density. We verify the importance of an isoscalar momentum
dependence of the mean field, which is found to influence the isospin transport
since it changes the reaction times. We finally suggest two observables
particularly sensitive to the isovector part of the nuclear equation-of-state:
the correlation between isospin equilibration and kinetic energy loss for
binary events, and the isospin content of the produced mid-rapidity fragments
for neck fragmentation events.Comment: 34 pages, 15 figures, Nucl.Phys. A, in pres
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