A research project entitled “Study on accuracy improvement of fast-neutron capture reaction data of long-lived MAs for development of nuclear transmutation systems” has been ongoing since 2017. The project aims at improving accuracies of neutron capture cross sections of long-lived minor actinides ($^{237}$Np, $^{241}$Am, $^{243}$Am) in the fast neutron energy region which are very important for development of nuclear transmutation systems. In order to improve the capture reaction data of MAs, measurements using an intense pulsed neutron beam from a spallation neutron source of the Japan Proton Accelerator Research Complex (J-PARC) are planned. The project consists of four parts: (1) development of neutron beam filter system in J-PARC, (2) neutron capture cross section measurement, (3) sample characteristic assay, and (4) theoretical reaction model study. The neutron beam filter system is designed to solve the so-called double bunch issue of a neutron beam in J-PARC. This allows for measuring neutron capture cross sections using the high-intensity neutron beam of J-PARC. The sample characteristic assay, particularly, precise isotope mass spectrometry lowers systematic uncertainties originating the samples. In the theoretical reaction model study, a nuclear reaction model is employed to analyze not only cross sections but also $\gamma$-ray spectra measured in experiments, and then improve accuracies of evaluated nuclear data. The outline of the project and the current progress will be presented.

This work is supported by the Innovative Nuclear Research and Development Program from the Ministry of Education, Culture, Sports, Science and Technology of Japan.