282 research outputs found
Application of the generalized two-center cluster model to 10Be
A generalized two-center cluster model (GTCM), including various partitions
of the valence nucleons around two alpha-cores, is proposed for studies on the
exotic cluster structures of Be isotopes. This model is applied to the 10Be =
alpha + alpha + n + n system and the adiabatic energy surfaces for alpha-alpha
distances are calculated. It is found that this model naturally describes the
formation of the molecular orbitals as well as that of asymptotic cluster
states dependeing on their relative distance. In the negative-parity state, a
new type of the alpha + 6He cluster structure is also predicted.Comment: 5 pages, 3 figure
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
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 structure in B
The cluster structures of the excited states in B are studied by
analyzing the isoscalar monopole and quadrupole strengths in the
B(,) reaction at MeV. The excitation strengths are
compared with the predictions by the shell-model and antisymmetrized
molecular-dynamics (AMD) calculations. It is found that the large monopole
strength for the state at MeV is well described by the AMD
calculation and is an evidence for a developed cluster structure.Comment: Revised according to the referees' comment
Existence of a phase transition under finite magnetic field in the long-range RKKY Ising spin glass DyYRuSi
A phase transition of a model compound of the long-range Ising spin glass
(SG) DyYRuSi, where spins interact via the RKKY
interaction, has been investigated. The static and the dynamic scaling analyses
reveal that the SG phase transition in the model magnet belongs to the
mean-field universality class. Moreover, the characteristic relaxation time in
finite magnetic fields exhibits a critical divergent behavior as well as in
zero field, indicating a stability of the SG phase in finite fields. The
presence of the SG phase transition in field in the model magnet strongly
syggests that the replica symmetry is broken in the long-range Ising SG.Comment: 4 pages, 4 figures, to be published in JPSJ (2010
Three-body hadron systems with strangeness
Recently, many efforts are being put in studying three-hadron systems made of
mesons and baryons and interesting results are being found. In this talk, I
summarize the main features of the formalism used to study such three hadron
systems with strangeness within a framework built on the basis of
unitary chiral theories and solution of the Faddeev equations. In particular, I
present the results obtained for the , and
systems and their respective coupled channels. In the first case, we find four
's and two 's with spin-parity , in the 1500-1800
MeV region, as two meson-one baryon s-wave resonances. In the second case, a
around 1900 MeV is found. For the last one a kaon close to 1420
MeV is formed, which can be identified with K(1460).Comment: Proceeding written for the HYP2012 conferenc
Deformed Base Antisymmetrized Molecular Dynamics and its Application to ^{20}Ne
A new theoretical framework named as deformed base antisymmetrized molecular
dynamics that uses the localized triaxially deformed Gaussian as the single
particle wave packet is presented. The model space enables us to describe
sufficiently well the deformed mean-field structure as well as the cluster
structure and their mixed structure within the same framework. The improvement
over the original version of the antisymmetrized molecular dynamics which uses
the spherical Gaussian is verified by the application to
nucleus. The almost pure cluster structure of the
= band, the distortion of the cluster structure in the
= band and the dominance of the deformed mean-field structure of
the = band are confirmed and their observed properties are
reproduced. Especially, the intra-band E2 transition probabilities in
= and bands are reproduced without any effective charge.
Since it has been long known that the pure
cluster model underestimates the intra-band transitions in the
= band by about 30%, we consider that this success is due to the
sufficient description of the deformed mean-field structure in addition to the
cluster structure by the present framework. From the successful description of
, we expect that the present framework presents us with a
powerful approach for the study of the coexistence and interplay of the
mean-field structure and the cluster structure
Important role of the spin-orbit interaction in forming the 1/2^+ orbital structure in Be isotopes
The structure of the second 0^+ state of ^{10}Be is investigated using a
microscopic model based on the molecular-orbit (MO) model.
The second 0^+ state, which has dominantly the (1/2^+)^2 configuration, is
shown to have a particularly enlarged structure. The kinetic
energy of the two valence neutrons occupying along the axis is
reduced remarkably due to the strong clustering and, simultaneously,
the spin-orbit interaction unexpectedly plays important role to make the energy
of this state much lower. The mixing of states with different spin structure is
shown to be important in negative-parity states. The experimentally observed
small-level spacing between 1^- and 2^- (~ 300 keV) is found to be an evidence
of this spin-mixing effect. ^{12}{Be} is also investigated using
model, in which four valence neutrons are considered to
occupy the (3/2^-)^2(1/2^+)^2 configuration. The energy surface of ^{12}Be is
shown to exhibit similar characteristics, that the remarkable
clustering and the contribution of the spin-orbit interaction make the binding
of the state with (3/2^-)^2(1/2^+)^2 configuration properly stronger in
comparison with the closed p-shell (3/2^-)^2(1/2^-)^2 configuration.Comment: 14 pages, 4 figure
Triaxial deformation in 10Be
The triaxial deformation in Be is investigated using a microscopic
model. The states of two valence neutrons are classified
based on the molecular-orbit (MO) model, and the -orbit is introduced
about the axis connecting the two -clusters for the description of the
rotational bands. There appear two rotational bands comprised mainly of and , respectively, at low excitation energy, where the two
valence neutrons occupy or orbits. The
triaxiality and the -mixing are discussed in connection to the molecular
structure, particularly, to the spin-orbit splitting. The extent of the
triaxial deformation is evaluated in terms of the electro-magnetic transition
matrix elements (Davydov-Filippov model, Q-invariant model), and density
distribution in the intrinsic frame. The obtained values turned out to be
.Comment: 15 pages, latex, 3 figure
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