Studies by using the tandem accelerator in the fields of atomic and molecular physics, solid state physics, and materials science.

<< Atomic collisions processes of high energy heavy ions >>
High-energy ions from the tandem accelerator are the highly charged ions, which are ions stripped off many electrons. The fast ions are usually highly stripped in materials. The fundamental processes of the interaction between radiation and materials has been studied from the measurements of emitted-particles (electrons, photons, ions etc.) in the collisions of highly charged ions and atoms, molecule and solid state materials.

<< Effect of high density electronic excitation on materials irradiated with swift heavy ions >>
 Heavy ions in the energy range of~100 MeV induce high-density electronic excitation in materials. We have studied the effects of the electronic excitation on structure, electrical conductivity and magnetic properties of materials such as metals and high Tc superconductors.

<< Irradiation effects of high TC superconductors >>
The improvement of critical current density or flux pinning of high Tc superconductors has been studied by high energy heavy ions are quite effective for the improvement of the critical current density.

<< Irradiation effects of solid breeder material >>
 Lithium silicate (Li4SiO4) is one of the candidates of tritium breeder materials in a fusion reactor. In Li4SiO4, the network structure in the glassy state induced by oxygen ion irradiation is measured by photo-acoustic spectroscopy (FTIRPAS), and the result of the measurements is compared with molecular orbital calculation.

<< Irradiation Effects of nuclear fuels >>
Disappearance of as-manufactured surface pores was observed in UO2 by irradiation of heavy ions such as iodine ions, in the study related with structural charge (so-called "rim effect") observed in highly burn-out nuclear fuels of a light water reactor.  The production of lattice defects by electronic excitation was also suggested.  For the development of the so-called rock-like fuel containing plutonium and inert matrix for plutonium burning, swelling, amorphization and thermal annealing have been studied for alumina, spinel and zirconia by heavy ion irradiation from the viewpoint of irradiation stability of these inert matrices.

<< Irradiation effect of semimetals and semiconductors at low temperature >>
 Electronic properties of semimetals and semiconductors show pronounced behavior at low temperature. Irradiation effect for the electronic properties has been measured in situ during heavy ion irradiation at low temperature.

Studies for nuclear physics, nuclear structure and nuclear chemistry by using high-energy heavy-ion beams.

<< Synthesis of new nuclei >>
 The cross section for synthesis of super-heavy elements is extremely small as the atomic number increases in heavy-ion fusion reactions. To overcome this difficultly, the fusion between deformed nuclei is theoretically proposed as a promising fusion reaction with a large cross section to synthesize super-heavy elements. Using a recoil-mass separator installed at the one of the booster beam line has started experimental study for fusion of heavy deformed nuclei.

<< Study of superconductivity in nuclear reactions >>
Josephson effect, which is the tunneling of the current through a thin insulating barrier between two superconducting materials in the absence of voltage, is a well-known phenomenon. The ground states of nuclei of comparatively heavy elements are in superconducting state due to pairing interaction. When the nuclei in superconducting state collide each other at energies around the Coulomb barrier, the enhancement of the pair-nucleon-transfer of nucleons due to Josephson effect is expected. The enhancement of the transfer between the ground state has been studied by use of the heavy ion spectrometer with high resolution.

<< Study of nuclear structure by nuclear spectroscopy >>
 Nuclei produced by nuclear fusion, coulomb excitation and deep-inelastic scattering are in highly excited states, and the information of the various excited nuclei is deduced from the measurements of the γ-rays emitted from the excited nuclei. The deformed co-existence phenomenon and electromagnetic nature in the high spin states of nuclei, and also the nuclear structures of neutron-rich nuclei have been studied by use of multi-gamma ray detectors and an isomer-scope in the collaborations with universities.

<< Applied γ-ray spectroscopy >>
 Analysis of gamma-gamma matrix derived from the gamma ray detector array (GEMINI), which can detect very weak radiation by an assemble of many detectors, can attain over thousand times discriminating sensitivity for gamma rays compared with the ordinary method. Very small amounts, ppb(10-9) order, of nuclei can be separated for βdecay nuclei. This high analytical sensitivity has been utilized for the studies of chemical analysis, the transmutation study of nuclear waste with long lifetime, and acquisition of fundamental data for decay heat emitted from fission fragment in a nuclear reactor. These studies contribute the development of novel atomic power.

<< Interdisciplinary study between nuclear and solid state physics >>
Angular distribution and angular correlation of γ-ray from unstable nuclei or nuclei in excited states implanted into solids provide the information about hyperfine interactions between nuclei and solids. By use of perturbed angular correlation and perturbed angular distribution, the interesting interdisciplinary field in solid state physics will be developed in the studies such as electromagnetic moment of nucleus, structure analysis of crystalline solids, and microscopic observation of radiation effects in solids.

<< Study of chemical and nuclear properties of heavy elements >>
Studies of chemical properties of the transactinide elements-starting with element 104(Rf)-offer the unique opportunity to obtain information about trends in the Periodic Table at the limits of nuclear stability and to assess the magnitude of the influence of relativistic effects on chemical properties. The main subject of the present group is to explore experimentally the influence of the relativistic effects on the electron shell structure by studying the chemical properties of the transactinides. As concerns the study of nuclear properties, search for unknown isotopes and decay studies of nuclei far from stability are being performed with the gas-jet coupled JAERI-ISOL system. Fission mechanism in the region of extensive actinide nuclei is studied with the double velocity time-of-fight technique.