[en] Present activities at the Institute for Nuclear Study (INS) are presented. Selected topics are from recent experiments by use of the INS cyclotron, experiments at the Bevalac facility under the INS-LBL collaboration program, and preparatory works for the Numatron project, a new project for the high-energy heavy-ion physics. (author)

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[en] An experiment is proposed to determine systematically the radii of the nuclei produced through the projectile fragmentation process in high energy heavy-ion collision. The measurement of total reaction cross section using the projectile fragments of a single nuclide on a target give information about nuclear radii. The production cross section of the fragments is appreciable for many nuclides. Therefore, it is possible to map systematically the reaction radii of the nuclei which can be produced as the projectile fragments. In an experiment using the projectile fragments as the incident beam, the cross section can be expressed as a function of the radii of a projectile and a target. An experiment with He-8 produced by the fragmentation of C-12 is proposed. The He-8 has four neutrons in the p-3/2 orbit outside the He-4 core. Proton and neutron distributions for He isotopes were calculated on the basis of the Hartree-Fock method. The information related to this kind of distribution can be obtained by the proposed experiment. The nuclear structure effect is seen in the nuclear radii of other unstable nuclei. The experimental examples of the isotope shift measurement and the excitation energy are presented. (Kato, T.)

[en] A project of high energy heavy ion acceleration is under consideration. The high energy heavy ions can produce highly condensed states of nuclei. A new phase of nucleus would be seen at the incident energy higher than 140 MeV/nucleon. High energy heavy ions causing high density states and meson emission will produce various new nuclides. Process of formation of atomic elements will be studied. Various fields of science can be also investigated by the high energy heavy ions. Spectroscopic study of multi-valent ions will be made high energy uranium. Study of materials for the fusion reactor is important. Impurity heavy ion from the wall of the fusion reactor may lose the energy of the reactor, and the characteristic features of heavy ions should be investigated. The highly ionized states of atoms are also produced by heavy ion injection into material. Several projects of heavy ion acceleration are in progress in the world. The Numatron project in Japan is to construct a combination machine of a Cockcroft type machine, three linear accelerator and a synchrotron. The planned energy of the machine is 670 MeV/nucleon. Technical problems are under investigation. (Kato, T.)

[en] The decay asymmetries (A) in polarized ¹²B and ¹²N have been measured as a function of β-ray energy, E. The coefficients asub(+-), in A=+-P(p/E)(1+asub(+-)E), have been determined to be a-(¹²B)=+(0.31+-0.06)%/MeV and a+(¹²N)=-(0.21+-0.07)%/MeV. The experimental value, asub(-)-asub(+)=(0.52+-0.09)%/MeV, is larger than the prediction according to conservation of vector current, (asub(-)-asub(+))cvc asymptotically equals 0.27%/MeV, which includes no second-class current. Thus, the result is in favor of the existence of the second-class induced-tensor current. (auth.)

[en] Polarization phenomena in the nuclear reaction, the nuclear moments, the β decay and the hyperfine interaction which have been studied in the Van de Graaff Laboratory, Osaka University, were discussed. Short history of the laboratory was also reviewed. (author)

[en] Temperature dependences of hyperfine interactions of ¹²B implanted in Ni were investigated in the temperature range of 6 K - 730 K by the NMR method with use of polarized ¹²B produced in a nuclear reaction and the asymmetric β decay. Two kinds of hyperfine fields with different signs were observed (B sub(hf)sup(+) = +4.161 +- 0.022 kG and B sub(hf)sup(-) = -1.611 +- 0.021 kG at 6 K), which indicated that the implanted ¹²B were trapped in two different sites (S⁺ and S^-, respectively). The spin-lattice relaxation times T₁ and the population rates at the two sites were studied. Near the Curie temperature, an effect of critical slowing-down of the spin-spin correlation was observed as steep variation of T₁. The behavior of local field around T sub(C) was also studied by varying the external field. Results of these experiments near T sub(C) indicate itinerant nature of the electron-spin structure in nickel. (author)

No abstract available