1,368 research outputs found
Nuclear incompressibility using the density dependent M3Y effective interaction
A density dependent M3Y effective nucleon-nucleon (NN) interaction which was
based on the G-matrix elements of the Reid-Elliott NN potential has been used
to determine the incompressibity of infinite nuclear matter. The nuclear
interaction potential obtained by folding in the density distribution functions
of two interacting nuclei with this density dependent M3Y effective interaction
had been shown earlier to provide excellent descriptions for medium and high
energy and heavy ion elastic scatterings as well as and heavy
cluster radioactivities. The density dependent parameters have been chosen to
reproduce the saturation energy per nucleon and the saturation density of spin
and isospin symmetric cold infinite nuclear matter. The result of such
calculations for nuclear incompressibility using the density dependent M3Y
effective interaction based on the G-matrix elements of Reid-Elliott NN
potential predicts a value of about 300 MeV for nuclear incompressibility.Comment: 4 Page
Parametric bootstrap mean squared error of a small area multivariate EBLUP
© 2018, © 2018 Taylor & Francis Group, LLC. This article deals with mean squared error (MSE) estimation of a multivariate empirical best linear unbiased predictor (MEBLUP) under the unit-level multivariate nested-errors regression model for small area estimation via parametric bootstrap. A simulation study is designed to evaluate the performance of our algorithm and compare it with the univariate case bootstrap MSE which has been shown to be consistent to the true MSE. The simulation shows that, in line with the literature, MEBLUP provides unbiased estimates with lower MSE than EBLUP. We also provide a short empirical analysis based on real data collected from the U.S. Department of Agriculture
Continuous phase transition and negative specific heat in finite nuclei
The liquid-gas phase transition in finite nuclei is studied in a heated
liquid-drop model where the nuclear drop is assumed to be in thermodynamic
equilibrium with its own evaporated nucleonic vapor conserving the total baryon
number and isospin of the system. It is found that in the liquid-vapor
coexistence region the pressure is not a constant on an isotherm indicating
that the transition is continuous. At constant pressure, the caloric curve
shows some anomalies, namely, the systems studied exhibit negative heat
capacity in a small temperature domain. The dependence of this specific feature
on the mass and isospin of the nucleus, Coulomb interaction and the chosen
pressure is studied. The effects of the presence of clusters in the vapor phase
on specific heat have also been explored.Comment: 18 pages, 13 figures; Phys. Rev. C (in press
Isoscalar Giant Dipole Resonance and Nuclear Matter Incompressibility Coefficient
We present results of microscopic calculations of the strength function,
S(E), and alpha-particle excitation cross sections sigma(E) for the isoscalar
giant dipole resonance (ISGDR). An accurate and a general method to eliminate
the contributions of spurious state mixing is presented and used in the
calculations. Our results provide a resolution to the long standing problem
that the nuclear matter incompressibility coefficient, K, deduced from sigma(E)
data for the ISGDR is significantly smaller than that deduced from data for the
isoscalar giant monopole resonance (ISGMR).Comment: 4 pages using revtex 3.0, 3 postscript figures created by Mathematica
4.
The rapid decline of the prompt emission in Gamma-Ray Bursts
Many gamma ray bursts (GRBs) have been observed with the Burst-Alert and
X-Ray telescopes of the Swift satellite. The successive `pulses' of these GRBs
end with a fast decline and a fast spectral softening, until they are overtaken
by another pulse, or the last pulse's decline is overtaken by a less
rapidly-varying `afterglow'. The fast decline-phase has been attributed, in the
currently-explored standard fireball model of GRBs, to `high-latitude'
synchrotron emission from a collision of two conical shells. This high latitude
emission does not explain the observed spectral softening. In contrast, the
temporal behaviour and the spectral evolution during the fast-decline phase
agree with the predictions of the cannonball model of GRBs.Comment: Four added figures comparing the evolution of the inferred effective
photon spectral index during the fast decline phase of the prompt emission in
14 selected Swift GRBS and the cannonball (CB) model predictio
Nuclear matter incompressibility coefficient in relativistic and nonrelativistic microscopic models
We systematically analyze the recent claim that nonrelativistic and
relativistic mean field (RMF) based random phase approximation (RPA)
calculations for the centroid energy E_0 of the isoscalar giant monopole
resonance yield for the nuclear matter incompressibility coefficient, K_{nm},
values which differ by about 20%. For an appropriate comparison with the RMF
based RPA calculations, we obtain the parameters for the Skyrme force used in
the nonrelativistic model by adopting the same procedure as employed in the
determination of the NL3 parameter set of an effective Lagrangian used in the
RMF model. Our investigation suggest that the discrepancy between the values of
K_{nm} predicted by the relativistic and nonrelativistic models is
significantly less than 20%.Comment: Revtex file (13 pages), appearing in PRC-Rapid Com
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