32,918 research outputs found
Proton rich nuclei at and beyond the proton drip line in the Relativistic Mean Field theory
Ground state properties of proton-rich odd- nuclei in the region are studied in the relativistic mean field (RMF) theory. The RMF
equations are solved by using the expansion method in the Harmonic-Oscillator
basis. In the particle-particle channel, we use the state-dependent BCS method
with a zero-range -force, which has been proved to be effective even
for neutron-rich nuclei. All the ground state properties, including the
one-proton separation energies, the ground state deformations, the last
occupied proton orbits and the locations of proton drip line, are calculated.
Good agreement with both the available experimental data and the predictions of
the RHB method are obtained.Comment: the version to appear in Progress of Theoretical Physics, more
discussions adde
Masses, Deformations and Charge Radii--Nuclear Ground-State Properties in the Relativistic Mean Field Model
We perform a systematic study of the ground-state properties of all the
nuclei from the proton drip line to the neutron drip line throughout the
periodic table employing the relativistic mean field model. The TMA parameter
set is used for the mean-field Lagrangian density, and a state-dependent BCS
method is adopted to describe the pairing correlation. The ground-state
properties of a total of 6969 nuclei with and from the
proton drip line to the neutron drip line, including the binding energies, the
separation energies, the deformations, and the rms charge radii, are calculated
and compared with existing experimental data and those of the FRDM and HFB-2
mass formulae. This study provides the first complete picture of the current
status of the descriptions of nuclear ground-state properties in the
relativistic mean field model. The deviations from existing experimental data
indicate either that new degrees of freedom are needed, such as triaxial
deformations, or that serious effort is needed to improve the current
formulation of the relativistic mean field model.Comment: 16 pages, 5 figures, to appear in Progress of Theoretical Physic
A systematic study of neutron magic nuclei with N = 8, 20, 28, 50, 82, and 126 in the relativistic mean field theory
We perform a systematic study of all the traditional neutron magic nuclei
with = 8, 20, 28, 50, 82, and 126, from the neutron drip line to the proton
drip line. We adopt the deformed relativistic mean field (RMF) theory as our
framework and treat pairing correlations by a simple BCS method with a
zero-range -force. Remarkable agreement with the available experimental
data is obtained for the binding energies, the two- and one-proton separation
energies, and the nuclear charge radii. The calculated nuclear deformations are
compared with the available experimental data and the predictions of the FRDM
mass formula and the HFBCS-1 mass formula. We discuss, in particular, the
appearance of sub-shell magic nuclei by observing irregular behavior in the
two- and one-proton separation energies.Comment: the version to appear in Journal of Physics G; more references adde
Relativistic description of nuclear matrix elements in neutrinoless double- decay
Neutrinoless double- () decay is related to many
fundamental concepts in nuclear and particle physics beyond the standard model.
Currently there are many experiments searching for this weak process. An
accurate knowledge of the nuclear matrix element for the decay
is essential for determining the effective neutrino mass once this process is
eventually measured. We report the first full relativistic description of the
decay matrix element based on a state-of-the-art nuclear
structure model. We adopt the full relativistic transition operators which are
derived with the charge-changing nucleonic currents composed of the vector
coupling, axial-vector coupling, pseudoscalar coupling, and weak-magnetism
coupling terms. The wave functions for the initial and final nuclei are
determined by the multireference covariant density functional theory (MR-CDFT)
based on the point-coupling functional PC-PK1. The low-energy spectra and
electric quadrupole transitions in Nd and its daughter nucleus
Sm are well reproduced by the MR-CDFT calculations. The
decay matrix elements for both the
and decays of Nd are evaluated. The effects
of particle number projection, static and dynamic deformations, and the full
relativistic structure of the transition operators on the matrix elements are
studied in detail. The resulting decay matrix element for the
transition is , which gives the most optimistic
prediction for the next generation of experiments searching for the
decay in Nd.Comment: 17 pages, 9 figures; table adde
Channel Parameters Estimation Algorithm Based on The Characteristic Function under Impulse Noise Environment
Under communication environments, such as wireless sensor networks, the noise observed usually exhibits impulsive as well as Gaussian characteristics. In the initialization of channel iterative decoder, such as low density parity check codes, it is required in advance to estimate the channel parameters to obtain the prior information from the received signals. In this paper, a blind channel parameters estimator under impulsive noise environment is proposed, which is based on the empirical characteristic function in MPSK/MQAM higher-order modulation system. Simulation results show that for various MPSK/MQAM modulations, the estimator can obtain a more accurate unbiased estimation even though we do not know which kind of higher-order modulation is used
A feasibility study for the detection of upper atmospheric winds using a ground based laser Doppler velocimeter
A possible measurement program designed to obtain the information requisite to determining the feasibility of airborne and/or satellite-borne LDV (Laser Doppler Velocimeter) systems is discussed. Measurements made from the ground are favored over an airborne measurement as far as for the purpose of determining feasibility is concerned. The expected signal strengths for scattering at various altitude and elevation angles are examined; it appears that both molecular absorption and ambient turbulence degrade the signal at low elevation angles and effectively constrain the ground based measurement of elevation angles exceeding a critical value. The nature of the wind shear and turbulence to be expected are treated from a linear hydrodynamic model - a mountain lee wave model. The spatial and temporal correlation distances establish requirements on the range resolution, the maximum detectable range and the allowable integration time
Octet baryon masses in next-to-next-to-next-to-leading order covariant baryon chiral perturbation theory
We study the ground-state octet baryon masses and sigma terms using the
covariant baryon chiral perturbation theory (ChPT) with the
extended-on-mass-shell (EOMS) renormalization scheme up to
next-to-next-to-next-to-leading order (NLO). By adjusting the available 19
low-energy constants (LECs), a reasonable fit of the lattice quantum
chromodynamics (LQCD) results from the PACS-CS, LHPC, HSC, QCDSF-UKQCD and
NPLQCD collaborations is achieved. Finite-volume corrections to the lattice
data are calculated self-consistently. Our study shows that NLO BChPT
describes better the light quark mass evolution of the lattice data than the
NNLO BChPT does and the various lattice simulations seem to be consistent with
each other. We also predict the pion and strangeness sigma terms of the octet
baryons using the LECs determined in the fit of their masses. The predicted
pion- and strangeness-nucleon sigma terms are MeV and
MeV, respectively.Comment: 28 pages, 6 figures, minor revisions, typos corrected, version to
appear in JHE
Laser Doppler velocimeter system simulation for sensing aircraft wake vortices. Part 2: Processing and analysis of LDV data (for runs 1023 and 2023)
A data analysis program constructed to assess LDV system performance, to validate the simulation model, and to test various vortex location algorithms is presented. Real or simulated Doppler spectra versus range and elevation is used and the spatial distributions of various spectral moments or other spectral characteristics are calculated and displayed. Each of the real or simulated scans can be processed by one of three different procedures: simple frequency or wavenumber filtering, matched filtering, and deconvolution filtering. The final output is displayed as contour plots in an x-y coordinate system, as well as in the form of vortex tracks deduced from the maxima of the processed data. A detailed analysis of run number 1023 and run number 2023 is presented to demonstrate the data analysis procedure. Vortex tracks and system range resolutions are compared with theoretical predictions
Laser Doppler velocimeter system simulation for sensing aircraft wake vortices
A hydrodynamic model of aircraft vortex wakes in an irregular wind shear field near the ground is developed and used as a basis for modeling the characteristics of a laser Doppler detection and vortex location system. The trailing vortex sheet and the wind shear are represented by discrete free vortices distributed over a two-dimensional grid. The time dependent hydrodynamic equations are solved by direct numerical integration in the Boussinesq approximation. The ground boundary is simulated by images, and fast Fourier Transform techniques are used to evaluate the vorticity stream function. The atmospheric turbulence was simulated by constructing specific realizations at time equal to zero, assuming that Kolmogoroff's law applies, and that the dissipation rate is constant throughout the flow field. The response of a simulated laser Doppler velocimeter is analyzed by simulating the signal return from the flow field as sensed by a simulation of the optical/electronic system
- …