11,533 research outputs found
The stability and the shape of the heaviest nuclei
In this paper, we report a systematic study of the heaviest nuclei within the
relativistic mean field (RMF) model. By comparing our results with those of the
Hartree-Fock-Bogoliubov method (HFB) and the finite range droplet model (FRDM),
the stability and the shape of the heaviest nuclei are discussed. The
theoretical predictions as well as the existing experimental data indicate that
the experimentally synthesized superheavy nuclei are in between the fission
stability line, the line connecting the nucleus with maximum binding energy per
nucleon in each isotopic chain, and the -stability line, the line
connecting the nucleus with maximum binding energy per nucleon in each isobaric
chain. It is shown that both the fission stability line and the
-stability line tend to be more proton rich in the superheavy region.
Meanwhile, all the three theoretical models predict most synthesized superheavy
nuclei to be deformed.Comment: 6 pages, 7 figures, to appear in Journal of Physics
From the stress response function (back) to the sandpile `dip'
We relate the pressure `dip' observed at the bottom of a sandpile prepared by
successive avalanches to the stress profile obtained on sheared granular layers
in response to a localized vertical overload. We show that, within a simple
anisotropic elastic analysis, the skewness and the tilt of the response profile
caused by shearing provide a qualitative agreement with the sandpile dip
effect. We conclude that the texture anisotropy produced by the avalanches is
in essence similar to that induced by a simple shearing -- albeit tilted by the
angle of repose of the pile. This work also shows that this response function
technique could be very well adapted to probe the texture of static granular
packing.Comment: 8 pages, 8 figures, accepted version to appear in Eur. Phys. J.
Reflection asymmetric relativistic mean field approach and its application to the octupole deformed nucleus Ra
A Reflection ASymmetric Relativistic Mean Field (RAS-RMF) approach is
developed by expanding the equations of motion for both the nucleons and the
mesons on the eigenfunctions of the two-center harmonic-oscillator potential.
The efficiency and reliability of the RAS-RMF approach are demonstrated in its
application to the well-known octupole deformed nucleus Ra and the
available data, including the binding energy and the deformation parameters,
are well reproduced.Comment: 4 pages, 2 figures, and 2 tables, to appear in Chinese Physics
Letter
Alpha-decay chains of and in the Relativistic Mean Field theory
In the recent experiments designed to synthesize the element 115 in the
Am+Ca reaction at Dubna in Russia, three similar decay chains
consisting of five consecutive -decays, and another different decay
chain of four consecutive -decays are detected, and the decay
properties of these synthesized nuclei are claimed to be consistent with
consecutive -decays originating from the parent isotopes of the new
element 115, and , respectively\cite{ogan.03}. Here in
the present work, the recently developed deformed RMF+BCS method with a
density-independent delta-function interaction in the pairing channel is
applied to the analysis of these newly synthesized superheavy nuclei
, , and their -decay daughter nuclei. The
calculated -decay energies and half-lives agree well with the
experimental values and with those of the macroscopic-microscopic FRDM+FY and
YPE+WS models. In the mean field Lagrangian, the TMA parameter set is used.
Particular emphasis is paid on the influence to both the ground-state
properties and energy surfaces introduced by different treatments of pairing.
Two different effective interactions in the particle-particle channel, i.e.,
the constant pairing and the density-independent delta-function interaction,
together with the blocking effect are discussed in detail.Comment: 17 pages, 5 figure
Switchable opening and closing of a liquid marble via ultrasonic levitation
Liquid marbles have promising applications in the field of microreactors, where the opening and closing of their surfaces plays a central role. We have levitated liquid water marbles using an acoustic levitator and, thereby, achieved the manipulation of the particle shell in a controlled manner. Upon increasing the sound intensity, the stable levitated liquid marble changes from a quasi-sphere to a flattened ellipsoid. Interestingly, a cavity on the particle shell can be produced on the polar areas, which can be completely healed when decreasing the sound intensity, allowing it to serve as a microreactor. The integral of the acoustic radiation pressure on the part of the particle surface protruding into air is responsible for particle migration from the center of the liquid marble to the edge. Our results demonstrate that the opening and closing of the liquid marble particle shell can be conveniently achieved via acoustic levitation, opening up a new possibility to manipulate liquid marbles coated with non-ferromagnetic particles
Study of Radiative Leptonic D Meson Decays
We study the radiative leptonic meson decays of D^+_{(s)}\to
\l^+\nu_{\l}\gamma (\l=e,\mu,\tau), and D^0\to
\l^+\l^-\gamma () within the light front quark model. In the standard
model, we find that the decay branching ratios of , and
are (), (), and
(), and that of D^0\to\l^+\l^-\gamma (\l=e,\mu) and
are and ,
respectively.Comment: 23 pages, 6 Figures, LaTex file, a reference added, to be published
in Mod. Phys. Lett.
Spurious Shell Closures in the Relativistic Mean Field Model
Following a systematic theoretical study of the ground-state properties of
over 7000 nuclei from the proton drip line to the neutron drip line in the
relativistic mean field model [Prog. Theor. Phys. 113 (2005) 785], which is in
fair agreement with existing experimental data, we observe a few spurious shell
closures, i.e. proton shell closures at Z=58 and Z=92. These spurious shell
closures are found to persist in all the effective forces of the relativistic
mean field model, e.g. TMA, NL3, PKDD and DD-ME2.Comment: 3 pages, to appear in Chinese Physics Letter
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