نتایج جستجو برای: neutron density
تعداد نتایج: 452104 فیلتر نتایج به سال:
A precise determination of the neutron skin Δr(np) of a heavy nucleus sets a basic constraint on the nuclear symmetry energy (Δr(np) is the difference of the neutron and proton rms radii of the nucleus). The parity radius experiment (PREX) may achieve it by electroweak parity-violating electron scattering (PVES) on (208)Pb. We investigate PVES in nuclear mean field approach to allow the accurat...
Neutrino emissivity from the electron νν̄ bremsstrahlung in the liquid layers of the neutron star crusts is studied. Nuclear composition of matter in neutron star crusts is considered for various scenarios of neutron star evolution. For the deep layers of the crust, the compositions of cold catalyzed matter, accreted matter and hot matter (T >∼ 5 × 10 9 K) are shown to be very different, and thi...
In this paper, we describe the performance of the Los Alamos spallation-driven solid-deuterium ultra-cold neutron (UCN) source. Measurements of the cold neutron flux, the very low energy neutron production rate, and the UCN rates and density at the exit from the biological shield are presented and compared to Monte Carlo predictions. The cold neutron rates compare well with predictions from the...
We discuss three different ways to arrive at kaon condensation at nc ≃ 3n0 where n0 is nuclear matter density: (1) Fluctuating around the n = 0 vacuum in chiral perturbation theory, (2) fluctuating around nVM near the chiral restoration density nχ where the vector manifestation of hidden local symmetry is reached and (3) fluctuating around the Fermi liquid fixed point at ∼ n0. They all share on...
Emissions of free neutrons and protons from the central collisions of Sn+Sn and Sn+Sn reactions are simulated using the Improved Quantum Molecular Dynamics model with two different density dependence of the symmetry energy in the nuclear equation of state. The constructed double ratios of the neutron to proton ratios of the two reaction systems are found to be sensitive to the symmetry terms in...
We assess the stability of Kruskal-Schwarzschild (magnetic Rayleigh-Taylor) type modes for accreted matter on the surface of a neutron star confined by a strong (& 10 G) magnetic field. Employing the energy principle to analyze the stability of short-wavelength ballooning modes, we find that line-tying to the neutron star crust stabilizes these modes until the overpressure at the top of the neu...
While model-independent limits are always interesting, a limit on neutron star radius as a function of mass attains special interest in light of recent interpretations of the periodic as well as quasi-periodic oscillations (QPOs) in brightness of X-rays emitted from neutron stars that are accreting matter from a low-mass companion. Here we derive such a limit based only on well accepted princip...
Porosity is one of the fundamental petrophysical properties that should be evaluated for hydrocarbon bearing reservoirs. It is a vital factor in precise understanding of reservoir quality in a hydrocarbon field. Log data are exceedingly crucial information in petroleum industries, for many of hydrocarbon parameters are obtained by virtue of petrophysical data. There are three main petrophysical...
different methods exist for the zonation of oil reservoirs based on petrophysical data and well logs. among them are: permeability-porosity cross polt, pickett and soder and gill methods. in this study a statistical zonation technique has been used for the marun and pazanan oil reservoirs in iran based on effective porosity, density, sonic, neutron and resistivity data. petrophysical interpreta...
The interpretation of Fourier spectra in the time domain is critically examined. Power density spectra defined and calculated in the time domain are compared with Fourier spectra in the frequency domain for three different types of variability: periodic signals, Markov processes and random shots. The power density spectra for a sample of neutron stars and black hole binaries are analyzed in bot...
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