111 research outputs found
Cluster structure in stable and unstable nuclei
Cluster structure in stable and unstable nuclei has been studied. We report
recent developments of theoretical studies on cluster aspect, which is
essential for structure study of light unstable nuclei. We discuss negative
parity bands in even-even Be and Ne isotopes and show the importance of cluster
aspect. Three-body cluster structure and cluster crystallization are also
introduced. It was found that the coexistence of cluster and mean-field aspect
brings a variety of structures to unstable nuclei.Comment: 6 pages, 3 figures, submitted to Euro. Phys. J.
Structure of Excited States of 10Be studied with Antisymmetrized Molecular Dynamics
We study structure of excited states of 10Be with the method of variation
after spin parity projection in the framework of antisymmetrized molecular
dynamics. Present calculations describe many excited states and reproduce the
experimental data of E2 and E1 transitions and the new data of the
transition strength successfully. We make systematic discussions on the
molecule-like structures of light unstable nuclei and the important role of the
valence neutrons based on the results obtained with the framework which is free
from such model assumptions as the existence of inert cores and clusters.Comment: 15 pages, RevTex, seven postscript figures (using epsf.sty
Cluster formations in deformed states for Si and S
We study cluster formation in strongly deformed states for Si and
S using a macroscopic-microscopic model. The study is based on
calculated total-energy surfaces, which are the sums of deformation-dependent
macroscopic-microscopic potential-energy surfaces and rotational-energy
contributions. We analyze the angular-momentum-dependent total-energy surfaces
and identify the normal- and super-deformed states in Si and S,
respectively. We show that at sufficiently high angular momenta strongly
deformed minima appear. The corresponding microscopic density distributions
show cluster structure that closely resemble the O+C and
O+O configurations. At still higher deformations, beyond the
minima, valleys develop in the calculated surfaces. These valleys lead to mass
divisions that correspond to the target-projectile configurations for which
molecular resonance states have been observed. We discuss the relation between
the one-body deformed minima and the two-body molecular-resonance states.Comment: 6 pages, 7 figure
Proton dominance in the 2^+_2 -> 0^+_1 transition of N = Z\pm 2 nuclei around Si-28
E2 transitions in Si-30 are investigated in relation with intrinsic
deformations based on a method of antisymmetrized molecular dynamics. By
comparing E2 transition strengths in the mirror nuclei Si-30 and S-30,
transition matrix amplitudes M_p and M_n for protons and neutrons are discussed
in mirror analysis. Particular attention is paid to the M_n/M_p ratio in the
transition from the 2^+_2 state to the 0^+_1 state. The M_n/M_p ratio in Mg-26
and Si-26 is also investigated. It is found that the proton dominance in the
transition 2^+_2 -> 0^+_1 in Si-30 and Si-26 originates in the oblate trend of
the Z=14 proton structure.Comment: 7 pages, 7 figure
New effective nuclear forces with a finite-range three-body term and their application to AMD+GCM calculations
We propose new effective inter-nucleon forces with a finite-range three-body
operator. The proposed forces are suitable for describing the nuclear structure
properties over a wide mass number region, including the saturation point of
nuclear matter. The forces are applied to microscopic calculations of
() nuclei and O isotopes with a method of antisymmetrized molecular
dynamics. We present the characteristics of the forces and discuss the
importance of the finite-range three-body term.Comment: 15 pages, 11 figures, submitted to Phys.Rev.
Structure of excited states of Be-11 studied with Antisymmetrized Molecular Dynamics
The structures of the ground and excited states of Be-11 were studied with a
microscopic method of antisymmetrized molecular dynamics. The theoretical
results reproduce the abnormal parity of the ground state and predict various
kinds of excited states. We suggest a new negative-parity band with a
well-developed clustering structure which reaches high-spin states. Focusing on
a clustering structure, we investigated structure of the ground and
excited states. We point out that molecular orbits play important roles for the
intruder ground state and the low-lying states. The features of
the breaking of clusters were also studied with the help of data for
Gamow-Teller transitions.Comment: 24 pages, 7 figures, to be submitted to Phys.Rev.
Cluster structures of excited states in C
Structures of excited states in C are investigated with a method of
- constraint antisymmetrized molecular dynamics in combination
with the generator coordinate method. Various excited states with the developed
-cluster core structures are suggested in positive- and
negative-parity states. In the positive-parity states, triaxial deformed and
linear-chain structures are found to construct excited bands. Interestingly,
Be+ correlation is found in the cluster states above the
Be+ threshold energy.Comment: 17 pages, 9 figure
Exotic clusters in the excited states of Be-12, Be-14 and B-15
The excited states of Be-12, Be-14 and B-15 were studied by an
antisymmetrized molecular dynamics method. The theoretical results reproduced
the energy levels of recently measured excited states of Be-12, and also
predicted rotational bands with innovative clustering structures in Be-12,
Be-14 and B-15. Clustering states with new exotic clusters (He-6, He-8 and
Li-9) were theoretically suggested. One new aspect in very neutron-rich nuclei
is a 6-nucleon correlation among 4 neutrons and 2 protons, which plays an
important role in the formation of He-6 clusters during clustering: 8He + 6He
of Be-14 and 9Li+6He of B-15.Comment: 8 pages, 3 figures. submitted to Phys.Rev.
Axial vector tetraquark with S=+2
Possibility of an axial vector isoscalar tetraquark with
is discussed. If the pentaquark has the
configuration, the isoscalar
(-meson) state with is expected to
exist in the mass region lower than or close to the mass of .
Within a flux-tube quark model, a possible resonant state of
is suggested to appear around 1.4 GeV with the
width MeV. We propose that the -meson is a
good candidate for the tetraquark search, which would be observed in the
decay channel.Comment: 20 pages, 5 figures, submitted to Phys.Rev.
Microscopic coupled-channel calculation of proton and alpha inelastic scattering to the and states of
The triaxial and hexadecapole deformations of the and bands of Mg have been investigated by the inelastic scatterings of various probes, including electrons, protons, and alpha() particles, for a prolonged time. However, it has been challenging to explain the unique properties of the scatterings observed for the state through reaction calculations. This paper investigates the structure and transition properties of the and bands of Mg employing the microscopic structure and reaction calculations via inelastic proton and scattering. In particular, the transitions to the and states are reexamined. The structure of Mg was calculated employing the variation after the parity and total angular momentum projections in the framework of the antisymmetrized molecular dynamics (AMD). The inelastic proton and reactions were calculated by the microscopic coupled-channel (MCC) approach by folding the Melbourne -matrix interaction with the AMD densities of Mg. Reasonable results were obtained on the properties of the structure, including the energy spectra and and transitions of the and bands owing to the enhanced collectivity of triaxial deformation. The MCC+AMD calculation successfully reproduced the angular distributions of the and cross sections of proton scattering at incident energies of â100 MeV and scattering at â400 MeV. This is the first microscopic calculation to describe the unique properties of the transition. In the inelastic scattering to the state, the dominant two-step process of the transitions and the deconstructive interference in the weak one-step process were essential
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