Chikako Ishizuka

We present sets of equation of state (EOS) of nuclear matter including hyperons using an SU_f(3) extended relativistic mean field (RMF) model with a wide coverage of density, temperature, and charge fraction for numerical simulations of core collapse supernovae. Coupling constants of Sigma and Xi hyperons with the sigma meson are determined to fit the hyperon potential depths in nuclear matter, U_Sigma(rho_0) ~ +30 MeV and U_Xi(rho_0) ~ -15 MeV, which are suggested from recent analyses of hypero

We developed a four-dimensional (4D) Langevin model, which can treat the deformation of each fragment independently and applied it to low-energy fission of $^{236}\mathrm{U}$, the compound system of the reaction $n+^{235}\mathrm{U}$. The potential energy is calculated with the deformed two-center Woods-Saxon (TCWS) and the Nilsson-type potential with the microscopic energy corrections following the Strutinsky method and BCS pairing. The transport coefficients are calculated by macroscopic prescr

In this Rapid Communication, we try to settle down the controversial predictions on the effect of doubly magic nuclei $^{132}\mathrm{Sn}$ and $^{208}\mathrm{Pb}$ on the mass distributions of fission fragments of superheavy nuclei. For this, we have calculated the mass distribution of fission fragments of superheavy nuclei from $^{274}\mathrm{Hs}$ to $^{306}122$ within the dynamical four-dimensional Langevin approach. We have found that, in ``light'' superheavies, the influence of $^{208}\mathrm{

The independent and cumulative fission product yields (FPYs) and their covariance matrices were newly evaluated for thermal- and fast-neutron induced fission and spontaneous fission. We principally evaluated the independent isobaric charge distributions by taking account of available experimental data, especially putting emphasis on the shell and even-odd staggering in the fission yields by applying a Boltzmann factor including the shell and the pairing correction energies for the mass of fissio

We investigate the liquid-gas phase transition of dense matter in supernova explo-sion systematically from B = 1010 to 101 fm3 by using a relativistic mean eld approach and a fragment based statistical model. The boiling temperature is determined and found to remain to be high for low density. Calculated fragment distribution shows that heavy elements around the rst, second, and third peaks of r-process are abundantly formed as the baryon density increases at around the boiling temperatures insi

The $^{44}\mathrm{Ti}$ nucleus is believed to have a $^{40}\mathrm{Ca}+\ensuremath{\alpha}$ cluster structure; however, $\ensuremath{\alpha}$ ($^{4}\mathrm{He}$) cluster structure tends to be washed out when we allow its breaking due to the spin-orbit interaction. Nevertheless, $\ensuremath{\alpha}$ clustering in medium-heavy nuclei is a popular subject recently. The tensor interaction plays an essential role in the strong binding of the $^{4}\mathrm{He}$, which induces the two-particle--two-hol

Nuclear equation of state (EoS) plays an important role in understanding the formation of compact objects such as neutron stars and black holes. The true nature of the EoS has been a matter of debate at any density range not only in the nuclear physics but also in the astronomy and astrophysics. We have constructed a database of EoSs by compiling data from the literature. Our database contains the basic properties of the nuclear EoS of symmetric nuclear matter and of pure neutron matter. It also

We have developed a novel theoretical method to obtain independent fission product yields and prompt neutron observables by connecting mass and total kinetic energy (TKE) distributions calculated by a four-dimensional Langevin dynamical model to a Hauser-Feshbach statistical decay model. In the Langevin calculations, mass distributions corresponding to the standard I and II modes were obtained separately and superposed to reproduce the fission fragment yield of spontaneous fission of 238,240,242

Understanding of fission properties of super-heavy nuclei (SHN) is essential not only for the synthesis of new elements but also for astrophysical nucleosynthesis because fission fragments from SHN are recycled as the seed nuclei of the r-process. A recent discovery of the r-process site by the gravitational wave observations requires more precise nuclear information for the detailed simulation of the r-process nucleosynthesis. However, the fission mechanisms of the SHN are not understood well,

Abstract We have studied the strength of the Bardeen–Cooper–Schrieffer (BCS) pairing force, used as a residual interaction to the relativistic mean-field approach, to reproduce the height of the inner fission barriers for actinide nuclei. It was found that increasing the pairing strength by about $13\%$ makes the reproduction of the inner fission barriers better over a wide range of actinide nuclei. This result was verified by using the moment of inertia of the pairing rotational energy, which w

We propose a new nucleosynthesis process in which various nuclei are formed through the liquid-gas phase transition of supernova matter as a preprocess of the standard r-process, and study its possibility of realization qualitatively. In the relativistic mean field and statistical model calculations, we find that this process may take place and help the later r-process to proceed.

We utilized a two hidden-layer Bayesian neural network (BNN) model along with data augmentation (DA) to predict the energy dependence of fission product yields (FPY). In the BNN model, the JENDL-5 FPY data are separated into 80% for training and 20% for validation. Additionally, the training data are combined with experimental cumulative fission yields and calculated values by five-Gaussian model. The number of units in each layer and activation function were selected carefully to reproduce the

We have constructed a computational scheme to obtain energy spectra of reactor antineutrinos, including the inverse β-decay process through which they were to be detected. The antineutrino spectra from all the fission products were calculated based on the gross theory of β-decay. This data was combined with an inventory of fission products obtained by burnup calculations, and then multiplicity and reactor antineutrinos spectra were obtained by a summation calculation. We compared aggregate antin

Measurements of the isotope distribution of fission fragments, often denoted as the primary fission yield (pre-neutron yield) or independent fission yield (post-neutron yield) are still challenging at low excitation energies, so that it is important to investigate it within a theory. Such quantities are vital for applications as well. In this study, fragment distributions from the fission of U isotopes at low excitation energies are studied using a dynamical model. The potential energy surface i

It is a long standing problem in nuclear physics and astrophysics to determine the nuclear EoS, which is important in many astrophysical applications, such as simulations of supernova explosions and the constraint of the maximum mass of neutron stars. There are hundreds of published papers dealing with nuclear EoSs, while more than ten nuclear EoS tables are available in tabulated form. In spite of many published EOSs, only a small number of datasets are used in the astrophysical applications. T