Yuichi Sugahara

Relativistic mean-field theory for unstable nuclei with non-linear σ and ω terms

Abstract We search for a new parameter set for the description of stable as well as unstable nuclei in the wide mass range within the relativistic mean-field theory. We include a non-linear ω self-coupling term in addition to the non-linear σ self-coupling terms, the necessity of which is suggested by the relativistic Brueckner-Hartree-Fock (RBHF) theory of nuclear matter. We find two parameter sets, one of which is for nuclei above Z = 20 and the other for nuclei below that. The calculated results agree very well with the existing data for finite nuclei. The parameter set for the heavy nuclei provides the equation of state of nuclear matter similar to the one of the RBHF theory.

Can the equation of state of asymmetric nuclear matter be studied using unstable nuclei

Abstract The paper shows that nuclear radii and neutron skins do directly reflect the saturation density of asymmetric nuclear matter. The proton distributions in a nucleus have been found to be remarkably independent of the equation of state (EOS) of the asymmetric matter. It is the neutron distributions that are dependent on the EOS. Macroscopic model calculations have been performed over the entire range of the nuclear chart based on two popular phenomenological, but distinctively different, EOS: the SIII parameter set for the non-relativistic Skyrme Hartree-Fock theory and the TM1 parameter set in the relativistic mean field theory. The saturation density for a small proton fraction remains almost the same as the normal nuclear matter density for SIII EOS, but it becomes significantly small for the TM1 EOS. The key EOS parameters used to describe the saturation density are the density derivative of the symmetry energy and the incompressibility of symmetric nuclear matter, while the saturation energy is written using the symmetry energy alone as a good approximation. We conclude that a systematic experimental study of heavy unstable nuclei would enable us to determine the EOS of asymmetric nuclear matter at about the normal nuclear matter density with a fixed proton fraction down to about 0.3.

Relativistic many body approach for unstable nuclei and supernova

Abstract We study the properties of unstable nuclei and the equations of state of nuclear matter in the framework of the relativistic many body theory. We take the relativistic mean field (RMF) theory as a phenomenological theory with several parameters, whose form is constrained by the successful microscopic theory (RBHF), and whose values are extracted by using the experimental values of unstable nuclei. We find the outcome with the newly obtained parameter set (TMA) is promising in comparison with various experimental data. We study also the neutron star profiles with the equation of state of nuclear matter with the use of TMA.

Properties of nuclei far from the stability line in the relativistic hartree theory

Abstract The properties of infinite nuclear matter and spherical nuclei are studied in terms of the relativistic Hartree theory. The special emphasis is placed on the role of the rho-meson field, which provides the isovector interaction among nucleons, in determining nuclear properties far from the stability line. We find that the proton radius follows the neutron radius as the neutron number increases, by an amount which is not very sensitive to the rho-meson coupling strength. On the other hand, the neutron drip line depends largely on the rho-meson strength. Calculations with finite geometry show interesting shell effects, but the general tendency described above is unchanged.

An automatic image analysis system for RLGS films.

Abstract. The RLGS (Restriction Landmark Genome Scanning) method was originally developed as a powerful method for enabling viewing of thousands of restriction landmarks. It offers a tool for obtaining information about genetic loci, with a single RLGS profile displaying approximately 2000 restriction landmarks as spots. One of the most useful applications is RLGS spot mapping, which allows the efficient, low-cost construction of the genetic map of any organism. However, analyses of the profiles depend mainly on human visual observation and are tedious and laborious. Although several commercially available image analyzing systems for profile comparison have been examined, they cannot be used for the RLGS spot mapping system owing to the background characteristics of the RLGS profiles, unsatisfactory rates of correspondence, and inefficient correction of informative genetic data. We therefore developed a novel automatic image analysis system for RLGS spot mapping, using an original algorithm based on the binary image transferred from the original RLGS profile. This system was employed for identifying non-polymorphic and parental strain-specific polymorphic spots of the F1 mouse profile and yielded efficient initial screening of RLGS profiles.

A systematic study of even-even nuclei up to the drip lines within the relativistic mean field framework

Abstract We apply the relativistic mean field theory to study the ground state properties of about 2000 even-even nuclei from Z=8 to Z=120 up to the proton and neutron drip lines. The calculations have been done under the axial symmetry assumption and a quadratic constraint method in order to obtain all possible ground state configurations. We do not take into account the pairing correlation in the present study. The calculations are performed with the TMA parameter set. We explore the general trend of masses, radii and deformations in the whole region of the nuclear chart. Using the masses obtained from RMF theory, we calculate the r-process abundances and the r-process path.

Study of Light Nuclei in the Relativistic Mean Field Theory and the Non-Relativistic Skyrme-Hartree-Fock Theory

We study the ground state properties of light nuclei in the relativistic mean field theory and the non-relativistic Skyrme·Hartree-Fock theory. The systematics of the experimental binding energies are reproduced well in both theories, while the results for the matter radii have rather clear model dependence. We find that the isovector part of the nuclear interaction plays an important role to induce the inversion of 2s and 1d single particle levels, which causes the rapid increase of matter radii. In the light mass region, due to the smallness of the number of nucleons, the center-of·mass correction becomes important. In addition, through the self·consistency, the nuclear potential for some nucleus differs clearly from those of the neighboring nuclei. In fact, we find some cases where these ingredients make it possible to reproduce the instability against particle emission without considering the effect of residual interaction.

Application of the RLGS image analysis tool (RAT) to the construction of a genetic linkage map of recombinant inbred strain SMXA

The construction of a genetic linkage map is the first, fundamental step to analyze the genetic properties of any organism. For this purpose, the restriction landmark genome scanning method (RLGS) can be used and has been shown to have high productivity in various genetic analyses. However, construction of a genetic linkage map by the RLGS method is laborious, because hundreds of spots must be scored, usually by visual observation. In order to reduce human involvement in the data processing, we developed an image analysis software, RAT (RLGS Analysis Tool). We evaluated its accuracy and feasibility by comparing the parental distribution patterns of RLGS spots obtained by RAT and by human observation, using Syrian hamster strain backcross progeny. We then used RAT to construct a genetic linkage map of the recombinant inbred strain SMXA. We were able to obtain 121 progenitor strain-specific spots that were assigned to a specific chromosome.