Sinobu Nagata

Tensor Force of the Pion-Theoretical Potential and the Doublet Splitting in n-He4 Scattering

To investigate whether the spin-orbit force in the theory of nuclear shell structure is due to the tensor force of the pion-theoretical potential, the doublet splitting of the pphase shifts in low energy n-He/sup 4/ scattering was analyzed. It is concluded that the major pant of the experimental doublet splitting can be reproduced by the strong tensor force of the pion-theoretical potential. It is shown qualitatively which features of the pton-theoretical potential are important to the binding energy of He/sup 4/ and the discontinuity of the binding energies between He/sup 4/ and the system of He/sup 4/ plus one nucleon. (auth)

Binding Energies of 4He and 3H in Reaction Matrix Theory

The binding energies of 4He and SH are calculated with some realistic potentials in the reaction matrix theory. The reaction matrix equation is derived from the internal Hamiltonian. The energy denominator is given after careful consideration of the difference between the total energies of the starting state and the intermediate state. The Pauli operator is treated without approximation in the two-particle scattering process in nuclei. The calculated binding energies of 4He and SH with Ramada-Johnston potential are 19.5MeV and 6.3MeV, respectively. The scattering wave function is also obtained. The root mean square radii with the correlated wave functions are 1.64fm and 1.67fm for 4He and SH, respectively. It is found that the contribution from tensor force in 3E state is very large, as compared with that in nuclear matter, and it is very important in order to obtain the sufficient binding energies of light nuclei to take into account this contribution through the two-particle scattering process in nuclei. The D state mixing ratios are about 14% and 8.5% for 4He and SH, respectively. The various correlation energies are estimated and it is found in the case of 4He with H-J that the hole-hole diagram contributes about 3MeV and potential insertion in the particle states just above the Fermi surface brings about 2 MeV. It is concluded that validity of the independent pair model is confirmed very well in the lightest nuclei similarly to the case of nuclear matter.

EFFECTIVE HAMILTONIAN AND ENERGY GAP IN FINITE NUCLEI

An effective hamiltonian is derived for finite nuclei from the original one that contains a hard-core interaction. The former has a screened hard-core interaction and is used to treat the phenomena near the ground state of the nuclei. Thus it gives a base for the calculation in the shell model. As an example, the energy gap is calculated for Ni/sup 60/ by applying Bogoliubovs method to the effective hamiltonian. (auth)

REACTION MATRIX THEORY FOR CLUSTER STATES IN LIGHT NUCLEI. II. CLUSTERING DEPENDENCE OF THE EFFECTIVE INTERACTION.

The states with triangular and linear chain configurations of three a-clusters in C12 are treated by the reaction matrix theory on the basis of a realistic nuclear force. Clustering dependence of G-matrix is found to be essential for clusterization. It also ·brings on a change of effective interaction between the two configurations, which has a role in reducing the excitation energy of the linear chain state. Its origin is mainly in the triplet even-state tensor force.

Heavy Ion Cllision with Friction Model

16 0+ 16 0 collisions at intermediate energies. The fusion window appears for ECM=80 MeV. The temperature of 16 0 can reach ~4.5 (4.0) MeV for ECM=160 (80) MeV, when the heavy ion potential evaluated by using the density· dependent nucleon-nucleon interaction and the chosen friction coefficients estimated with the potential are employed in the equations. The time evolution of the nuclear temperature is obtained consistently with the damping of the relative motion. Important ingredients that control the heavy ion trajectories are discussed.

Foundation of Deformed Potential Model for Nuclear Rotation

Following the methods of Bohr and Mottelson, a formulation of the separation of the nuclear Hamiltonian in to rotational and intrinsic parts is developed. In the light of this formulation, the foundation of various methods with the deformed potential model for the estimation of the moments of inertia for nuclear rotation is discussed and the interrelation among these methods is clarified. Treatments are restricted to the two dimensional case for simplicity. (auth)