Shinsho Oryu

Cluster structures in Oxygen isotopes

Cluster structures of 16 O, 18 Oa nd 20 O are investigated using the antisymmetrized molecular dynamics (AMD) plus generator coordinate method (GCM). We have found the K π =0 + and 0 � rotational bands of 18 O that have prominent 14 C+α cluster structure. The clustering systematics are richer in 20 O. We suggest the presence of a K π =0 + band that is a mixture of the 12 C+α+4n and 14 C+ 6 He cluster structures. K π =0 + and 0 � bands that have prominent 16 C+α cluster structure are also found.

A New Antisymmetrized Molecular Dynamics Approach to Few-Nucleon Systems

A new method in the study of antisymmetrized molecular dynamics (AMD) is proposed. This method consists of a Jacobi-coordinate-basis AMD with the generator coordinate method (GCM). A simple example is presented for the case of in few-nucleon systems with the Volkov potential. Bound states for 2N, 3N, and 4N systems are compared with those obtained using the “primary AMD” and some other methods. We find this to be a promising method for investigating light nuclear systems. During the past decade, since the primary antisymmetrized molecular dynamics (AMD) was proposed, 1)–3) it has been successfully extended to systematic studies of neutron-rich nuclei, 4)–6) as well as excited states of nuclei. 7) Further developments of the AMD method have been realized by introducing several conventional ideas of conventional nuclear structure physics. 8)–19) The physical approaches mentioned above were formulated by making improvements of the AMD in Refs. 4)–7); for instance, a variational calculation was carried out after application of the spin parity projection (VAP) in order to investigate excited states 15) and the existence of exotic clusters in excited states of neutronrich nuclei. 16)–19) Another improvement realized through use of the superposition of selected Slater determinants was made in the AMD triple-S model, which can quantitatively describe properties of light nuclei. 10),11) These improvements were made in methods treating medium light nuclei in which the wave function is expressed in terms of a superposition of Slater determinants. However, this method has not yet been successfully applied to few-body problems. In order to allow for the application of the AMD method to few-body and very light nuclei, we present one modified AMD method which was developed using the Jacobi-coordinate-basis AMD plus the GCM technique. 20),21) One of the aims of this work is to introduce the N-body correlations in a “single Slater determinant”. The second is to remove the ambiguity of the zero-point oscillation energy. The third is to reduce the number of variational parameters in the AMD effectively with the GCM technique; using this technique, a very large number of the variational parameters can be fixed in the eigenvalue problem. Let us start from the trial wave function primary AMD. The wave function of N -nucleon system Ψ is given by

Collective quantization of a gravitating Skyrmion

Collective quantization of a B=1 gravitating skyrmion is described. The rotational and isorotational modes are quantized in the same manner as the skyrmion without gravity. It is shown in this paper how the static properties of nucleons such as masses, charge densities, magnetic moments are modified by the gravitational interaction.

Proton–proton phase shifts calculations in momentum space by a rigorous Coulomb treatment

We present a two-body calculation method for a rigorous treatment of Coulomb interaction in momentum (p-)space. The method is based on a modified Coulomb potential which is equivalent to the genuine Coulomb potential in configuration (r-)space. We also use the two-potential theory with the auxiliary potential. The calculated proton–proton phase shifts are in very good agreement with the experimental data for the states 0 ⩽ l ⩽ 2. The phase shifts for the 3 ⩽ l ⩽ 5 states are also calculated. Practical applications of our method in a few hadron problems are discussed.

A New molecular dynamics calculation and its application to the spectra of light and strange baryons

A new approach based on antisymmetrized molecular dynamics is proposed to correctly take account of the many-body correlation. We applied it to the spectra of low-lying, light and strange baryons. The inclusion of the quark-quark correlation is vital to predict the precise spectra, and the semi-relativistic kinematics is also important to correct the level ordering. The baryon spectra calculated by the present method is as precise as the Faddeev calculation.

Nuclear data for astrophysical nucleosynthesis: A Japanese + LANL activity

There are many common features in nuclear data for energy applications and nuclear cosmology/astrophysics, especially the neutron‐capture nucleosynthesis. Therefore it is a natural consequence to think that many of the tools that we have developed for the conventional nuclear‐data applications can be applied for a development of a database for nuclear cosmology/astrophysics. However, there are also many features that are uncommon to these fields, so new development is necessary when we think about a database for nuclear cosmology and astrophysics. Such new development will then give us a new horizon for the conventional nuclear data activities as well. In this paper we will show the present status of our activities in this direction, putting emphasis on data relevant to neutron capture nucleosynthesis, namely s‐ and r‐processes.

D(p,p)D elastic scattering with rigorous Coulomb treatment

Low-energy D(p,p)D elastic scattering using a rigorous Coulomb treatment in momentum space is considered. The treatment is an extension of an exact two-body Coulomb theory?different from the approximate method which is based on a screened Coulomb potential. In contrast to the latter, the two-body Coulomb potential employed is fully equivalent to the pure Coulomb potential in configuration space. It is shown that the approximation based on the Coulomb half-shell function ensures the reliability of the renormalization method. The difference between the rigorous treatment and the approximate method is demonstrated by numerical results.

OFF-SHELL EFFECTS IN FEW-BODY SYSTEMS WITH COULOMB FORCE

The exact treatment of the two-body problem in momentum space in the presence of Coulomb forces is discussed. Convergence of the traditionally used renormalization approximation is investigated with respect to increasing ranges of the screened Coulomb potentials. The permissible energy range for this approximation is obtained for the first time in this work.

Polarization Effects on the Fusion Reaction in the 3/2+ Resonance Region A Nuclear, Three-Charged-Particle Faddeev-Type Formalism

A cross section enhancement of the 3 HE(d,p) 4 He fusion reaction in the 3/2 + resonance region is presented. It is pointed out that a residual interaction in a nuclear three-body system is generated by an atomic target with an electron-cloud, as is the case for atomic 3 He and the deuteron. A complete nuclear three-charged-particle Faddeev-type equation is derived for the first time in momentum space. Our formulation could be useful not only to investigate three-cluster systems with such a residual potential but also to obtain the astrophysical S-factor in the ultra low-energy region. The importance of a new renormalization amplitude is emphasized, which is missing in the previous renormalization method.

Search For the Quark Shell Structure Using the Non-Topological Soliton Model

We investigate higher baryon-number states in the Chiral Quark Soliton Model using the rational map ansatz for the background chiral fields. The soliton solutions are obtained self-consistently. We show that the baryon number density lias point-like symmetries and the corresponding valence quark spectrum of the lowest energy exhibits approximate four-fold degenerate. Our results indicate the possibility of existence of the shell-like structure in the multi-baryonic system.