Considering all the matter in the universe as an assembly of elements, the most fundamental unit of the matter is atom. The nature of the atom is characterized by its nucleus, and all the elements in the universe were synthesized by nuclear reactions. The nuclear physics is, as it were, the field to explore the origin of the matter in the universe. We aim to elucidate the origin of the matter by experimental research into extremely rare phenomena inside nuclei and structures of exotic nuclei such as hyper nuclei or unstable nuclei far from stability.
A nucleus, a many-body system of protons and neutrons governed by the strong interaction, exhibits various types of structures such as shell structure, collective structure, cluster structure, and so on. We carry out a series of experiments to explore such exotic structures at RCNP, Osaka University, at RIBF in RIKEN, and at TRIUMF in Canada.
The neutrino-less double beta decay does not conserve the lepton number before and after the decay (a violation of lepton number conservation). This lepton number violating process is an important key step toward explaining the evolution of the present matter-dominated universe. We are developing a large detector system, CANDLES, to search for the extremely rare neutrino-less double-beta decay of 48Ca nuclei at the Kamioka underground laboratory, Gifu.
We are also studying hypernuclei which are nuclear systems contain strange quarks. Hyper nuclei provide an insight into the generalized hadron-nucleus interaction to describe the inner structure of neutron stars as a hypernuclear matter. We are preparing an experiment to study hypernuclei at J-PARC, Ibaraki.
Material science is also a field we are investigating, where we apply the beta-ray detected nuclear magnetic resonance (β-NMR) and muon spin rotation/relaxation (μ SR) techniques. With these ultra-high sensitivity techniques, electron structures and local sub-nanometer-scale configuration in materials can be revealed.