Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

I formulate a many-body theory to calculate the cross section of direct radiative neutron capture reaction by means of the Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random-phase approximation (QRPA). A focus is put on very-neutron-rich nuclei and low-energy neutron kinetic energy in the range from 1 keV to several MeV, which is relevant to the rapid neutron capture process of nucleosynthesis. I begin with the photoabsorption cross section and the E1 strength function. Next, in order to apply the reciprocity theorem, I decompose the cross section into partial cross sections corresponding to different channels of one-and two-neutron emission decays of photo-excited states. A numerical example is shown for the photo-absorption of Sn-142 and the neutron capture of Sn-141.

DOI： 10.1103/PhysRevC.91.034604

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Low-lying quadrupole shape dynamics is a typical manifestation of large-amplitude collective motion in finite nuclei. To describe the dynamics on a microscopic foundation, we have formulated a consistent scheme in which the Bohr collective Hamiltonian for the five-dimensional quadrupole shape variables is derived on the basis of the time-dependent Hartree-Fock-Bogoliubov theory. It enables us to incorporate the Thouless-Valatin effect on the shape inertial functions, which has been neglected in previous microscopic Bohr Hamiltonian approaches. Quantitative successes are illustrated for the low-lying spectra in Se-68, Mg30-34 and Cr58-64, which display shape-coexistence, shape-mixing and shape-transitional behavior.

DOI： 10.1088/0031-8949/89/5/054020

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

We study microscopic structures of monopole pair vibrational modes and associated two-neutron transfer amplitudes in neutron-rich Sn isotopes by means of the linear response formalism of the quasiparticle random phase approximation (QRPA). For this purpose we introduce a method to decompose the transfer amplitudes with respect to two-quasiparticle components of the QRPA eigenmode. It is found that pair-addition vibrational modes in neutron-rich Sn132-140 and the pair rotational modes in Sn142-150 are commonly characterized by coherent contribution of quasaiparticle states having high orbital angular momenta l greater than or similar to 5, which suggests transfer of a spatially correlated neutron pair. The calculation also predicts a high-lying pair vibration, the giant pair vibration, emerging near the one-neutron separation energy in Sn110-130, and we find that they have the same di-neutron characters as that of the low-lying pair vibration in Sn132-140.

DOI： 10.1103/PhysRevC.88.054308

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP PUBLISHING LTD  

We apply the continuum quasiparticle random phase approximation to calculate the direct neutron capture cross section relevant to the r-process nucleo-synthesis. The electric dipole strength function in an even-even n-rich nucleus is decomposed with respect to the channels of direct neutron decays. Using the detailed balance relation, the partial dipole strengths are converted to obtain the direct neutron-capture cross sections. Numerical examples are given for Sn-142.

DOI： 10.1088/1742-6596/445/1/012019

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

The spherical-to-prolate shape transition in neutron-rich Cr isotopes from N = 34 to 42 is studied by solving the collective Schrodinger equation for the five-dimensional quadrupole collective Hamiltonian. The collective potential and inertial functions are microscopically derived with use of the constrained Hartree-Fock-Bogoliubov plus local quasiparticle random-phase approximation method. Nature of the quadrupole collectivity of low-lying states is discussed by evaluating excitation spectra and electric quadrupole moments and transition strengths. The result of calculation indicates that Cr isotopes around Cr-64 are prolately deformed but still possess transitional character; large-amplitude shape fluctuations dominate in their low-lying states.

DOI： 10.1103/PhysRevC.86.024316

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We have analyzed large-amplitude quadrupole collective dynamics in neutron-rich nuclei Mg30-36 using the five-dimensional quadrupole collective Hamiltonian approach. The collective Hamiltonian is microscopically derived with the constrained HFB plus local quasi-particle RPA method. Enhancement of the quadrupole collectivity from Mg-30 to Mg-34 is well described by the calculation. The shape transitional behavior in the ground band and the shape coexistence/mixing properties in the ground and excited 0(+) states are analyzed.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP PUBLISHING LTD  

We have developed a new method for determining microscopically the five-dimensional quadrupole collective Hamiltonian, on the basis of the adiabatic self-consistent collective coordinate method. This method consists of the constrained Hartree-Fock-Bogoliubov (HFB) equation and the local QRPA (LQRPA) equations, which are an extension of the usual QRPA (quasiparticle random phase approximation) to non-HFB-equilibrium points, on top of the CHFB states. One of the advantages of our method is that the inertial functions calculated with this method contain the contributions of the time-odd components of the mean field, which are ignored in the widely-used cranking formula. We illustrate usefulness of our method by applying to oblate-prolate shape coexistence in Kr-72 and shape phase transition in neutron-rich Cr isotopes around N = 40.

DOI： 10.1088/1742-6596/381/1/012103

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

Large-amplitude collective dynamics of shape phase transition in the low-lying states of Mg30-36 is investigated by solving the five-dimensional (5D) quadrupole collective Schrodinger equation. The collective masses and potentials of the 5D collective Hamiltonian are microscopically derived with use of the constrained Hartree-Fock-Bogoliubov plus local quasiparticle random phase approximation method. Good agreement with the recent experimental data is obtained for the excited 0(+) states as well as the ground bands. For Mg-30, the shape coexistence picture that the deformed excited 0(+) state coexists with the spherical ground state approximately holds. On the other hand, large-amplitude quadrupole-shaped fluctuations dominate in both the ground and the excited 0(+) states in Mg-32, providing a picture that is different from the interpretation of the "coexisting spherical excited 0(+) state" based on the naive inversion picture of the spherical and deformed configurations.

DOI： 10.1103/PhysRevC.84.061302

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DOI： 10.1103/PhysRevC.84.044317

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DOI： 10.1103/PhysRevC.83.054301

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：POLISH ACAD SCIENCES INST PHYSICS  

A new microscopic approach is proposed to derive the five-dimensional quadrupole collective Hamiltonian. It is based on the time-dependent mean-field theory and the adiabatic self-consistent collective coordinate method. We apply the method to studies of oblate-prolate shape coexistence/mixing phenomena and anharmonic vibrations. Experimental data for Se isotopes are well reproduced.

DOI： 10.5506/APhysPolB.42.443

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

We introduce a microscopic approach to derive all the inertial functions in the five-dimensional quadrupole collective Hamiltonian. Local normal modes are evaluated on the constrained mean field in the quasiparticle random-phase approximation in order to derive the inertial functions. The collective Hamiltonians for neutron-rich Mg isotopes are determined with use of this approach, and the shape coexistence/mixing around the N = 20 region is analyzed.

DOI： 10.1063/1.3584067

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

On the basis of the adiabatic self-consistent collective coordinate method, we develop an efficient microscopic method of deriving the five-dimensional quadrupole collective Hamiltonian and illustrate its usefulness by applying it to the oblate-prolate shape coexistence/mixing phenomena in proton-rich (68,70,72)Se. In this method, the vibrational and rotational collective masses (inertial functions) are determined by local normal modes built on constrained Hartree-Fock-Bogoliubov states. Numerical calculations are carried out using the pairing-plus-quadrupole Hamiltonian including the quadrupole-pairing interaction within the two major-shell active model spaces both for neutrons and protons. It is shown that the time-odd components of the moving mean-field significantly increase the vibrational and rotational collective masses in comparison with the Inglis-Belyaev cranking masses. Solving the collective Schrodinger equation, we evaluate excitation spectra, quadrupole transitions, and moments. The results of the numerical calculation are in excellent agreement with recent experimental data and indicate that the low-lying states of these nuclei are characterized as an intermediate situation between the oblate-prolate shape coexistence and the so-called gamma unstable situation where large-amplitude triaxial-shape fluctuations play a dominant role.

DOI： 10.1103/PhysRevC.82.064313

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DOI： 10.1103/PhysRevC.82.024318

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

We develop an efficient microscopic method of deriving the five-dimensional quadrupole collective Hamiltonian on the basis of the adiabatic self-consistent collective coordinate method. We illustrate its usefulness by applying it to the oblate-prolate shape coexistence/mixing phenomena and anharmonic vibrations in Se isotopes.

DOI： 10.1142/S0217732310000356

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

We discuss the pair transfer mode populating pair vibration 0(2)(+) state in neutron-rich Sn isotopes by means of the continuum quasi particle random phase approximation (continuum QRPA). It is seen that the strength of the two-neutron addition transfer from the ground state to the 0(2)(+) state is significantly enhanced beyond the N = 82 shell gap.

DOI： 10.1142/S0217732310000964

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

From a viewpoint of oblate-prolate symmetry and its breaking, we propose a simple model based on the quadrupole collective Hamiltonian to study dynamics of triaxial deformation in shape coexistence phenomena. The numerical results suggest that the oblate-prolate symmetry breaking in the rotational moments of inertia can play an important role for the oblate-prolate shape coexistence as well as that in the collective potential.

DOI： 10.1142/S0217732310000939

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

We develop a method of determining microscopically the collective potential and inertial masses in the five-dimensional quadrupole collective Hamiltonian on the basis of the adiabatic self-consistent collective coordinate method. We apply this method to shape coexistence/mixing phenomena in low-lying states of the proton-rich Kr isotopes.

DOI： 10.1142/S0217732310000940

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Construction of the microscopic theory of large-amplitude collective motion, capable of describing a wide variety of quantum collective phenomena in nuclei, is a long-standing and fundamental subject in the study of nuclear many-body systems. The present status of the challenge toward this goal is discussed taking the shape coexistence/mixing phenomena as typical manifestations of the large-amplitude collective motion at zero temperature. Some open problems in rapidly rotating cold nuclei are also briefly discussed in this connection.

DOI： 10.1088/0954-3899/37/6/064018

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Physics related to weakly bound nuclei and low-density asymmetric nuclear matter is discussed from a theoretical point of view. Especially, we focus our discussion on new correlations in nuclei near the drip lines and on open issues of the density functional theory with a proper account of the continuum.

DOI： 10.1088/0954-3899/37/6/064017

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

From the viewpoint of oblate-prolate symmetry and its breaking, we adopt the quadrupole collective Hamiltonian to study the dynamics of triaxial deformation in shape coexistence phenomena. It accommodates the axially symmetric rotor model, the gamma-unstable model, the rigid triaxial rotor model, and an ideal situation for the oblate-prolate shape coexistence as particular cases. Numerical solutions of this model yield a number of interesting suggestions. (1) The relative energy of the excited 0(+) state can be a signature of the potential shape along the gamma direction. (2) Specific E2 transition probabilities are sensitive to the breaking of the oblate-prolate symmetry. (3) Nuclear rotation may induce the localization of collective wave functions in the (beta, gamma) deformation space.

DOI： 10.1143/PTP.123.129

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

Features of the neutron pair correlation characteristic to neutron-rich nuclei are discussed on the basis of the Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random phase approximations. We discuss the monopole and quadrupole pair transfer modes in neutron-rich Sn isotopes beyond the N = 82 shell closure. We investigate also how the pair correlation behaves in deformed weakly bound nuclei, and we show that the neutron pairing enhances as the binding energy of neutrons becomes small.

DOI： 10.1063/1.3442639

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

The five-dimensional quadrupole collective Hamiltonian for large-amplitude collective dynamics is microscopically constructed by the constrained Hartree-Fock-Bogoliubov (CHFB) method and local quasiparticle random phase approximation (LQRPA). The excitation spectra and the electric quadrupole transitions between the low-lying states in Se-68 are calculated by solving the collective Schrodinger equation.

DOI： 10.1063/1.3455952

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

We present a new microscopic approach which consists of the constrained Hartree-Fock-Bogoliubov (CHFB) and the local quasiparticle random-phase approximation (LQRPA) to construct the five-dimensional quadrupole collective Hamiltonian for large-amplitude collective dynamics. The excitation spectra and the electric quadrupole transitions between the low-lying states in Se-68 are calculated by solving the collective Schrodinger equation.

DOI： 10.1063/1.3442638

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

We formulate a new Hartree-Fock-Bogoliubov method applicable to weakly bound deformed nuclei using the coordinate-space Green's function technique. An emphasis is put on treatment of quasiparticle states in the continuum, on which we impose the correct boundary condition of the asymptotic out-going wave. We illustrate this method with numerical examples.

DOI： 10.1142/S0218301309014202

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DOI： 10.1103/PhysRevC.80.024301

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

The oblate-prolate shape coexisting/mixing phenomena in proton-rich (68,70,72)Se are investigated by means of the adiabatic self-consistent collective coordinate (ASCC) method. The one-dimensional collective path and the collective Hamiltonian describing the large-amplitude shape vibration are derived in a fully microscopic way. The excitation spectra, B(E2) and spectroscopic quadrupole moments are calculated by requantizing the collective Hamiltonian and solving the collective Schroumldinger equation. The basic properties of the coexisting two rotational bands in low-lying states of these nuclei are well reproduced. It is found that the oblate-prolate shape mixing becomes weak as the rotational angular momentum increases. We point out that the rotational energy plays a crucial role in causing the localization of the collective wave function in the (beta,gamma) deformation space.

DOI： 10.1103/PhysRevC.80.014305

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DOI： 10.1103/PhysRevC.79.024313

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We investigate the low-lying octupole response of neutron-rich Ni isotopes beyond the N = 50 shell closure using the Skyrme-Hartree-Fock-Bogoliubov mean fields and the continuum quasi-particle random phase approximation. Performing detailed numerical analyses employing the Skyrme parameter set SLy4 and a density-dependent delta interaction of the mixed type, we show that a neutron mode emerges above the neutron separation energy as a consequence of the weak binding of neutrons and that it strongly influences the di-neutron correlation.

DOI： 10.1143/PTP.121.97

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

We formulate the coordinate-space Hartree-Fock-Bogoliubov (HFB) theory which can describe pair correlated and deformed nuclei near the drip-lines. In order to ensure the correct asymptotic form of weakly bound and continuum quasiparticle states, we adopt a coupled-channel representation based on the partial wave expansion, and then we construct the exact HFB Green's function. Numerical examples calculated for (38)Mg are discussed.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

Large-amplitude collective dynamics of oblate-prolate shape coexistence in the low-lying states of proton-rich Se-68,Se-70,Se-72 are studied. The collective path (collective submanifold) is extracted from the time-dependent Hartree-Fock-Bogoliubov (HFB) manifold by use of the adiabatic self-consistent collective coordinate (ASCC) method. The inertial functions for the large-amplitude collective vibration along the collective path and for the three-dimensional rotation are microscopically calculated. Solving the collective Schrodinger equation, excitation spectra, E2 transition probabilities, and spectroscopic quadrupole moments are evaluated.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We analyse the deformation mechanism in neutron-rich Cr, Fe and Ti isotopes with N = 32-44 using a Skyrme-Hartree-Fock-Bogoliubov mean-field code employing a two-dimensional mesh representation in the cylindrical coordinate system. Evaluating the quadrupole deformation energy systematically; we show that the Skyrme parameter set SkM* gives a quadrupole instability around the neutron numbers N similar to 38-42 in Cr isotopes, where the deformation energy curve suggests a transitional behavior with a shallow minimum extending to a. large prolate deformation. The roles of a deformed N = 38 gap and the position of the neutron g(9/2) orbit are analysed in detail.

DOI： 10.1143/PTP.120.143

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

The microscopic dynamics of oblate-prolate shape coexistence/mixing phenomena in (68) Se and Kr-72 are studied by means of the adiabatic self-consistent collective coordinate (ASCC) method in conjunction with the pairing-plus-quadrupole (P + Q) Hamiltonian, including the quadrupole pairing interaction. A quantum collective Hamiltonian is constructed, and excitation spectra, spectroscopic quadrupole moments and quadrupole transition properties are evaluated. The effect of the time-odd pair field on the collective mass (inertia function) of the large-amplitude vibration and the rotational moments of inertia about three principal axes is evaluated. It is found that the basic properties of the shape coexistence/mixing are qualitatively reproduced. The results of the calculation indicate that the oblate-prolate shape mixing decreases as the angular momentum increases.

DOI： 10.1143/PTP.119.59

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The adiabatic self-consistent collective coordinate (ASCC) method is a practical microscopic theory of large-amplitude collective motion in nuclei with superfluidity. We show that its basic equations are invariant under transformations involving the gauge angle in particle-number space. By virtue of this invariance, a clean separation of the large-amplitude collective motion and the pairing rotational motion can be made, and this allows us to restore the particle-number symmetry broken by the Hartree-Fock-Bogoliubov (HFB) approximation. We formulate the ASCC method explicitly in a gauge-invariant form. In solving the ASCC equations, it is necessary to fix the gauge. Applying this new formulation to the multi-O(4) model, we compare different gauge-fixing procedures and demonstrate that calculations using different gauges indeed yield the same results for gauge-invariant quantities, such as the collective path and quantum spectra. We propose a gauge-fixing prescription that seems most convenient in realistic calculations.

DOI： 10.1143/PTP.117.451

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We apply the adiabatic self-consistent collective coordinate (ASCC) method to the multi-O(4) model and study the collective mass (inertia function) of many-body tunneling motion. Comparing the results with those obtained from the exact diagonalization, we show that the ASCC method is capable of describing the gradual change of the excitation spectra from an anharmonic vibration about a spherical shape to a doublet pattern associated with a deformed double-well potential possessing oblate-prolate symmetry. It is found that the collective mass is significantly increased by the quadrupole-pairing contribution to time-odd components of the moving mean field. In contrast, the cranking (Inglis-Belyaev) mass based on the constrained mean field, which ignores the time-odd components, is smaller than the ASCC mass and fails to reproduce the exact spectra.

DOI： 10.1143/PTP.115.567

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMERICAN PHYSICAL SOC  

The neutron pairing correlation and the soft dipole excitation in medium mass nuclei near the drip line are investigated from the viewpoint of the di-neutron correlation. Numerical analyses based on the coordinate-space Hartree-Fock-Bogoliubov method and the continuum quasiparticle random phase approximation are performed for even-even O18-24,Ca50-58, and Ni80-86. A clear signature of the di-neutron correlation is found in the ground state; two neutrons are correlated at short relative distances less than or similar to 2 fm with large probability similar to 50%. The soft dipole excitation is influenced strongly by the neutron pairing correlation, and it accompanies a large transition density for pair motion of neutrons. This behavior originates from a coherent superposition of two-quasiparticle configurations [l x (l + 1)](L=1) consisting of continuum states with high orbital angular momenta l reaching an order of l similar to 10. It suggests that the soft dipole excitation under the influence of neutron pairing is characterized by the motion of di-neutron in the nuclear exterior against the remaining A-2 subsystem. Sensitivity to the density dependence of the effective pair force is discussed.

DOI： 10.1103/PhysRevC.71.064326

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Language：English   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

By means of the adiabatic self-consistent collective coordinate method and the pairing-plus-quadrupole interaction, we have for the first time obtained a self-consistent collective path connecting the oblate and prolate local minima in Se-68 and Kr-72. This self-consistent collective path is found to run approximately along the valley connecting the oblate and prolate local minima in the collective potential energy landscape. The result of this calculation clearly indicates the importance of triaxial deformation dynamics in oblate-prolate shape coexistence phenomena.

DOI： 10.1143/PTP.113.129

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

On the basis of the coordinate-space Hartree-Fock-Bogoliubov and the continuum quasiparticle random phase approximation (QRPA) theories, we demonstrate that a di-neutron correlation exists in the ground states of medium-mass neutron-rich nuclei near the dripline, and we suggest that the soft dipole excitation has the character of di-neutron motion against the remaining A - 2 subsystem.

DOI： 10.1140/epjad/i2005-06-045-9

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Language：English   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

By means of the adiabatic self-consistent collective coordinate method and the pairing-plus-quadrupole interaction, we have obtained a self-consistent collective path connecting the oblate and prolate local minima in Se-68 for the first time. The result of the calculation indicates the importance of triaxial deformation dynamics in oblate-prolate shape coexistence phenomena.

DOI： 10.1143/PTP.112.363

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

By using the continuum quasiparticle random phase approximation, which we recently formulated on the basis of the coordinate-space Hartree-Fock-Bogoliubov theory, we investigate pairing effects on the low-lying dipole strength in neutron rich oxygen isotopes near the drip-line. The neutron pairing enhances the dipole strength near the threshold, especially in the case of the surface pairing. Analysis shows that spatially correlated spin-singlet neutron pairs (di-neutrons) are formed in the external region, and the low-lying dipole strength is characterized by motion of the correlated neutron pairs against the core.

DOI： 10.1142/9789812703972_0039

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMERICAN PHYSICAL SOC  

In order to identify double-gamma vibrational states in well-deformed regions, we have made a Coulomb excitation experiment for Er-168. We could observe 1235-keV and 962-keV gamma transitions decaying from the 2056-keV 4(+) state. The measured E2 transition probabilities support the assignment of the 4(+) state as a two-phonon gamma-vibrational state.

DOI： 10.1103/PhysRevC.52.3492

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DOI： 10.1016/S0375-9474(01)01123-X

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DOI： 10.1016/S0375-9474(01)01133-2

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DOI： 10.1016/S0375-9474(00)00674-6

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DOI： 10.1143/PTP.103.959

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Language：English   Publisher：ELSEVIER SCIENCE BV  

The intrinsic width of (multiparticle-multihole) compound states is an elusive quantity, of difficult direct access, as it is masked by damping mechanisms which control the collective response of nuclei. Through microscopic cranked shell model calculations, it is found that the strength function associated with two-dimensional gamma-coincidence spectra arising from rotational transitions between states lying at energies > 1 MeV above the yrast line, exhibits a two-component structure controlled by the rotational (wide component) and compound (narrow component) damping width. This last component is found to be directly related to the width of the multiparticle-multihole autocorrelation function. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0370-2693(99)01058-8

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Unresolved γ rays of 114Te sorted into one- and two-dimensional spectra were studied. The reaction 64Ni(Ebeam = 230-270MeV)+54 Cr was used and the γ rays were detected with the EUROBALL array. The effective moment of inertia for the quasicontinuum was found to be almost constant for I=(20-40)ħ, in contrast with the decreasing behavior of the terminating yrast band. A comparative analysis with the nucleus 164Yb is presented and the results from a fluctuation analysis were compared with cranked shell model calculations. The comparison shows consistency in the scaling of the rotational damping width with mass number. © 1999 The American Physical Society.

DOI： 10.1103/PhysRevLett.83.5234

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DOI： 10.1103/PhysRevC.60.034307

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Language：English   Publisher：ELSEVIER SCIENCE BV  

We study static non-axial octupole deformations in proton-rich Z=N nuclei, Ge-64, Se-68, Kr-72, Sr-76, Zr-80 and Mo-84, by using the Skyrme Hartree-Fock plus BCS calculation with no restrictions on the nuclear shape. The calculation predicts that the oblate ground state in Se-68 is extremely soft for the Y-33 triangular deformation, and that in Zr-80 the low-lying local minimum state coexisting with the prolate ground state has the Y-32 tetrahedral deformation. (C) 1998 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0370-2693(98)00545-0

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Language：English   Publisher：PERGAMON PRESS LTD  

The rotational continuum for normally deformed nuclei of the rare earth region is investigated making use of statistical analysis methods, With these techniques it is possible to extract information on the rotational motion from the region of high level density, in this connection, two points will be discussed: i) the important role of the residual interaction in the description of the experimental data and ii) the dependence of the mixing among rotational bands on the symmetry quantum numbers of the nuclear states, This last point was investigated for the nucleus Er-163 for which it has been found that the gamma-cascades feeding into low-K bands are different from those feeding high-K bands, This result indicates that the K-selection rules are effective for excited rotational bands within the angular momentum 30h less than or equal to I less than or equal to 40h.

DOI： 10.1016/S0146-6410(97)00026-4

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DOI： 10.1007/s002180050310

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DOI： 10.1007/s002180050178

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DOI： 10.1103/PhysRevLett.76.4484

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DOI： 10.1016/0370-1573(95)00060-7

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Language：English   Publisher：ELSEVIER SCIENCE BV  

The study of damping of rotational motion applying the rotational plane mapping (RPM) method is presented and discussed. The aim of this technique is to extract the distribution of the rotational transition strength from an analysis of the shape of the ''central valley'' of two- and three-dimensional gamma-ray spectra. The method is applied to a triple gamma-coincidence data set of Tm-162,Tm-163 nuclei formed in Cl-37+Te-130 reactions. The rotational transition strength is obtained as a function of rotational frequency for selected regions of entry states, and the width is found to be rather constant and approximately equal to 80 keV. This value is significantly smaller than the value predicted theoretically for the rotational damping width Gamma(rct). Also the ratio between the observed depth and width of both the 2D and 3D valleys does not agree with the simple model adopted in the RPM method, These discrepancies point to the presence of both a wide and a narrow component in the distribution of rotational strength as extracted by the RPM method. The analysis of simulated spectra obtained on the basis of realistic band-mixing calculations, including residual interactions, confirms this behaviour.

DOI： 10.1016/0375-9474(95)00024-U

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DOI： 10.1016/0370-2693(95)00549-Z

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DOI： 10.1016/0375-9474(93)90541-5

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DOI： 10.1103/PhysRevLett.70.2694

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DOI： 10.1016/0375-9474(93)90542-6

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DOI： 10.1016/0375-9474(93)90540-E

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DOI： 10.1016/0375-9474(93)90648-H

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DOI： 10.1016/0375-9474(93)90509-V

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Language：English   Publisher：AMERICAN PHYSICAL SOC  

A statistical method to analyze the gamma decay of excited, rapidly rotating nuclei is presented. It is based on the fact that the cooling path of these systems goes through regions of both suppressed and enhanced fluctuations typical of large and low level density, respectively. The method is applied to the study of the high-spin quasicontinuum of Yb-167, Yb-168.

DOI： 10.1103/PhysRevLett.68.3008

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PubMed

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DOI： 10.1016/0146-6410(92)90023-U

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Language：English  

DOI： 10.1143/PTP.85.281

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CiNii Books

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Other Link： https://projects.repo.nii.ac.jp/?action=repository_uri&item_id=350141

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Language：English   Publisher：KYOTO UNIV  

Damping property of the collective vibration is numerically analyzed for a schematic shell model which simulates a giant collective vibration built on compound states. Microscopic mechanism of the motional narrowing of the damping width is investigated in reference to the residual interaction which causes configuration mixing. Statistical aspects of the damping mechanism are also discussed. It is shown that the response function method which we formulated in a preceding paper provides a consistent and microscopic description of the damped collective vibration embedded in the highly excited region.

DOI： 10.1143/PTP.84.1126

Web of Science

CiNii Article

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Language：English   Publisher：KYOTO UNIV  

DOI： 10.1143/PTP.84.269

Web of Science

CiNii Article

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Language：English   Publisher：ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS  

DOI： 10.1016/0003-4916(89)90031-6

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Language：English   Publisher：KYOTO UNIV  

DOI： 10.1143/PTP.78.609

Web of Science

CiNii Article

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DOI： 10.1143/PTP.78.591

CiNii Article

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DOI： 10.1143/PTP.76.93

CiNii Article

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