3,178 research outputs found
Structure of Light Unstable Nuclei Studied with Antisymmetrized Molecular Dynamics
Structures of light unstable nuclei, Li, Be, B, and C isotopes are
systematically studied with a microscopic method of antisymmetrized molecular
dynamics. The theoretical method is found to be very useful to study ground and
excited states of various nuclei covering unstable nuclei. The calculations
succeed to reproduce many experimental data for nuclear structures; energies,
radii, magnetic dipole moments, electric quadrupole moments, transition
strength. In the theoretical results it is found that various exotic phenomena
in unstable nuclei such as molecular-like structures, neutron skin, and large
deformations may appear in unstabel nuclei. We investigate the structure change
with the increase of neutron number and with the increase of the excitation
energies, and find the drastic changes between shell-model-like structures and
clustering structures. The mechanism of clustering developments in unstable
nuclei are discussed.Comment: 73 pages, Revtex, 42 postscript figures (using epsf.sty). to be
published in Suppl. Prog. Theor. Phy
Mariner Mars 1969 SCAN control subsystem design and analysis
Design and analysis of self correcting automatic navigation system for Mariner Mars spacecraf
New Treatment of Resonances with Bound State Approximation by Using Pseudo Potential
We propose a new approach to extract the wave functions of resonances by the
bound state approximation which gives the mixed states of the resonance
components and the continuum ones. In our approach, on the basis of the method
of analytic continuation in the coupling constant (ACCC), we construct Pad\'e
rational function by adopting the positive energies as well as the negative
ones. We report the result of the application of this new method to the second
state of C which was studied with the ACCC method in our previous
work. It is found that the resonance parameters obtained by the ACCC method are
well reproduced by the new method. Some advantages over the ACCC method are
also shown.Comment: 10pages, 2figures, submitted to Prog. Theor. Phys, changed content,
added reference
Clustering and Triaxial Deformations of Ca
We have studied the positive-parity states of Ca using antisymmetrized
molecular dynamics (AMD) and the generator coordinate method (GCM). Imposing
two different kinds of constraints on the variational calculation, we have
found various kinds of structures such as a deformed-shell
structure, as well as -Ar and C-Si cluster
structures. After the GCM calculation, we obtained a normal-deformed band and a
superdeformed band together with their side bands associated with triaxial
deformation. The calculated values agreed well with empirical data. It
was also found that the normal-deformed and superdeformed bands have a
non-negligible -Ar cluster component and C-Si
cluster component, respectively. This leads to the presence of an
-Ar higher-nodal band occurring above the normal-deformed band.Comment: 11pages, 9 figure
Structures and Transitions in Light Unstable Nuclei
We study the structures of the unstable Be isotopes with the theoretical
method of antisymmetrized molecular dynamics. It is found that various
structures of the excited states appear in the low-energy region of
neutron-rich Be nuclei. Focusing on the 2 clustering, we analyze the
intrinsic structures with the help of the experimental data of Gamow-Teller
transitions.Comment: 8 pages and 4 figure
Analysis of previous microscopic calculations for second state in C in terms of 3-alpha particle Bose-condensed state
The wave function of the second state of C which was obtained
long time ago by solving the microscopic 3 problem is shown to be
almost completely equivalent to the wave function of the 3 condensed
state which has been proposed recently by the present authors. This equivalence
of the wave functions is shown to hold in two cases where different effective
two-nucleon forces are adopted. This finding gives strong support for
interpreting the second state of C which is the key state for the
synthesis of C in stars ('Hoyle' state), and which is one of the typical
mysterious states in light nuclei, as a gas-like structure of three
particles, Bose-condensed into an identical s-wave function.Comment: revtex, 5 pages, 2 figures, submitted to Phys. Rev.
Alpha-cluster structure and density wave in oblate nuclei
Pentagon and triangle shapes in Si-28 and C-12 are discussed in relation with
nuclear density wave. In the antisymmetrized molecular dynamics calculations,
the band in Si-28 and the band in C-12 are described by
the pentagon and triangle shapes, respectively. These negative-parity bands can
be interpreted as the parity partners of the ground bands and they
are constructed from the parity-asymmetric-intrinsic states. The pentagon and
the triangle shapes originate in 7alpha and 3alpha cluster structures,
respectively. In a mean-field picture, they are described also by the static
one-dimensional density wave at the edge of the oblate states. In analysis with
ideal alpha cluster models using Brink-Bloch cluster wave functions and that
with a simplified model, we show that the static edge density wave for the
pentagon and triangle shapes can be understood by spontaneous breaking of axial
symmetry, i.e., the instability of the oblate states with respect to the edge
density wave. The density wave is enhanced in the Z=N nuclei due to the
proton-neutron coherent density waves, while it is suppressed in Z\ne N nuclei.Comment: 23 pages, 8 figure
Alpha-particle condensation in nuclei
A round up of the present status of the conjecture that n alpha nuclei form
an alpha-particle condensate in excited states close to the n alpha threshold
is given. Experiments which could demonstrate the condensate character are
proposed. Possible lines of further theoretical developments are discussed.Comment: 6 page
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