Search

Fission and capture reactions were simultaneously measured in the neutron-induced reactions of 241Am at the spallation neutron facility of the Japan Proton Accelerator Research Complex (J-PARC). Data for the neutron energy range of En=0.1–20 eV were taken with the TOF method. The fission events were observed by detecting prompt neutrons accompanied by fission using liquid organic scintillators. The capture reaction was measured by detecting γ rays emitted in the deexcitation of the compound nuclei using the same detectors, where the prompt fission neutrons and capture γ rays were separated by a pulse shape analysis. The cross sections were obtained by normalizing the relative yields at the first resonance to evaluations or other experimental data. The ratio of the fission to capture cross sections at each resonance is compared with those from an evaluated nuclear data library and other experimental data. Some differences were found between the present values and the library/literature values at several resonances.

Short-lived radioisotopes with half-lives of 0.1-10 Myr are known as nuclear cosmochronometers to evaluate the passing time from a nucleosynthesis event such as s-process in an AGB star or r-process to the solar system formation (SSF). Neutron rich short-lived radioisotopes such as 129I and 244Pu, which were predominantly produced by the r process, have been studied in order to evaluate the age of the last supernova (SN) around the solar system. However, the recent studies show neutron star mergers are a candidate for the r process. Thus, there is no robust cosmic clock for the last SN before the SSF. We focus our attention on neutron-deficient short-lived radioisotopes, in particular, which may be produced by neutrino-process. This is because the neutrino process can occur only in core-collapse SNe. In an early phase, a huge number of neutrinos are emitted from a proto neutron star formed in the center of a massive star. Some neutrinos interact with preexisting isotopes and thereby produce rare neutron deficient isotopes such as 138 La, and 180Ta as well as 7Li and 11B. There are five neutrino-deficient short-lived isotopes of 53Mn, 92Nb, 97Tc, 98Tc, 146Sm. We have proposed the neutrino-process origin for unstable isotopes for 92Nb (T1/2=35 Myr) and 98Tc (T1/2=4.2 Myr). We have calculated neutrino-induced reaction cross section involved using the QRPA model and statistical model. We have calculated the neutrino-isotope abundances in SNe using SN models. In the case of 92Nb, its initial abundance at SSF could be reproduced by the later input model. It is found that it is possible to explain the origin of 92Nb by the SN neutrino process. In contrast, for 98Tc, the upper limit for the initial abundance was reported. The calculated result is consistent with the observed upper limit. We discuss possible age for the last SN for various neutrino process chronometers., The 15th International Symposium on Origin of Matter and Evolution of Galaxies

Development of global ocean observing capacity for the biological EOVs is on the cusp of a step-change. Current capacity to automate data collection and processing and to integrate the resulting data streams with complementary data, openly available as FAIR data, is certain to dramatically increase the amount and quality of information and knowledge available to scientists and decision makers into the future. There is little doubt that scientists will continue to expand their understanding of what lives in the ocean, where it lives and how it is changing. However, whether this expanding information stream will inform policy and management or be incorporated into indicators for national reporting is more uncertain. Coordinated data collection including open sharing of data will help produce the consistent evidence-based messages that are valued by managers. The GODS Biology and Ecosystems Panel is working with other global initiatives to assist this coordination by defining and implementing Essential Ocean Variables. The biological EOVs have been defined, are being updated following community feedback, and their implementation is underway. In 2019, the coverage and precision of a global ocean observing system capable of addressing key questions for the next decade will be quantified, and its potential to support the goals of the UN Decade of Ocean Science for Sustainable Development identified. Developing a global ocean observing system for biology and ecosystems requires parallel efforts in improving evidence-based monitoring of progress against international agreements and the open data, reporting and governance structures that would facilitate the uptake of improved information by decision makers.

There exist a lot of important quantities which have their origin in aggregate behavior of unstable fission products (FP) in nuclear reactors. Decay heat is a typical example of importance. These quantities are calculated by summing up all the contributions coming from each unstable nucleus accumulated during reactor operation by using of FP decay data libraries. In their infancy, however, they were suffered from so-called the pandemonium problem. For decades, the difficulty caused by pandemonium problem has been circumvented by introduction of a β-decay theory. In recent years, the total absorption gamma-ray spectroscopy (TAGS) is saving the situation remarkably even though leaving some open problems.