Shuhei Yamaji

THE PROTON AND NEUTRON DISTRIBUTIONS IN NA ISOTOPES : THE DEVELOPMENT OF HALO AND SHELL STRUCTURE

The interaction cross sections for

Transport coefficients for shape degrees in terms of Cassini ovaloids

^A Na + ^{12}C

Variation of transport coefficients for average fission dynamics with temperature and shape

reaction are calculated using Glauber model. The continuum Hartree-Bogoliubov theory has been generalized to treat the odd particle system and take the continuum into account. The theory reproduces the experimental result quite well. The matter distributions from the proton drip line to the neutron drip line in Na isotopes have been systematically studied and presented. The relation between the shell effects and the halos has been examined. The tail of the matter distribution shows a strong dependence on the shell structure. The neutron N=28 closure shell fails to appear due to the coming down of the

On the nature of nuclear dissipation, as a hallmark for collective dynamics at finite excitation

2p_{3/2}

The pseudo-spin symmetry in a Dirac equation

and

Study of the Gamow-Teller resonance in 90Nb and 208Bi

2p_{1/2}

Determination of Matter Surface Distribution of Neutron-rich Nuclei

. The development of the halo was understood as changes in the occupation in the next shell or the sub-shell close to the continuum limit. The central proton density is found to be decreasing near the neutron drip line, which is due to the proton-neutron interaction. However the diffuseness of the proton density does not change for the whole Na isotopes.Abstract The interaction cross sections for A Na + 12 C reaction are calculated using Glauber model. The continuum Hartree-Bogoliubov theory has been generalized to treat the odd particle system and take the continuum into account. The theory reproduces the experimental result quite well. The matter distributions from the proton drip line to the neutron drip line in Na isotopes have been systematically studied and presented. The relation between the shell effects and the halos has been examined. The tail of the matter distribution shows a strong dependence on the shell structure. The neutron N =28 closure shell fails to appear due to the coming down of the 2 p 3/2 and 2 p 1/2 . The development of the halo was understood as changes in the occupation in the next shell or the sub-shell close to the continuum limit. The central proton density is found to be decreasing near the neutron drip line, which is due to the proton-neutron interaction. However the diffuseness of the proton density does not change for the whole Na isotopes.

Model-Independent Determination of Surface Density Distribution of Unstable Nuclei at Radioactive Beam Facilities

Previous computations of the potential landscape with the shapes parameterized in terms of Cassini ovaloids are extended to collective dynamics at finite excitations. Taking fission as the most demanding example of large scale collective motion, transport coefficients are evaluated along a fission path. We concentrate on those for average motion, namely stiffness C, friction \gamma and inertia M. Their expressions are formulated within a locally harmonic approximation and the help of linear response theory. Different approximations are examined and comparisons are made both with previous studies, which involved different descriptions of single particle dynamics, as well as with macroscopic models. Special attention is paid to an appropriate definition of the deformation of the nuclear density and its relation to that of the single particle potential. For temperatures above 3 MeV the inertia agrees with that of irrotational flow to less than a factor of two, but shows larger deviations below, in particular in its dependence on the shape. Also friction exhibits large fluctuations along the fission path for small excitations. They get smoothed out above 3 - 4 MeV where \gamma attains values in the range of the wall formula. For T>(or=) 2 MeV the inverse relaxation time \beta = \gamma /M turns out to be rather insensitive to the shape and increases with T.

Target-charge dependence of the Coulomb dissociation cross section of 11Li

We study slow collective motion at finite thermal excitations on the basis of linear response theory applied to the locally harmonic approximation. The transport coefficients for average motion, friction γ, inertia M and the local stiffness C are computed along a fission path of 224Th within a quasi-static picture. The inverse relaxation time β = γM and the effective damping rate η=γ(2 M|C|) are found to increase with temperature, but do not change much with the collective variable. The values found for η and β as well as their behavior with temperature are in accord with experimental findings.

Microscopic calculation of the mass diffusion coefficient using linear response theory

Abstract We study slow collective motion of isoscalar type at finite excitation. The collective variable is parameterized as a shape degree of freedom and the mean field is approximated by a deformed shell model potential. We concentrate on situations of slow motion, as guaranteed, for instance, by the presence of a strong friction force, which allows us to apply linear response theory. The prediction for nuclear dissipation of some models of internal motion are contrasted. They encompass such opposing cases as that of pure independent particle motion and the one of “collisional dominance”. For the former the wall formula appears as the macroscopic limit, which is here simulated through Strutinsky smoothing procedures. It is argued that this limit hardly applies to the actual nuclear situation. The reason is found in large collisional damping present for nucleonic dynamics at finite temperature T . The level structure of the mean field as well as the T -dependence of collisional damping determine the T -dependence of friction. Two contributions are isolated, one coming from real transitions, the other being associated to what for infinite matter is called the “heat pole”. The importance of the latter depends strongly on the level spectrum of internal motion, and thus is very different for “adiabatic” and “diabatic” situations, both belonging to different degrees of “ergodicity”.