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Spin-polarized radioactive nuclear beams at TRIUMF enable a new spectroscopic method which efficiently assigns spins and parities of the daughter levels by taking advantage of the asymmetric β-decay of the polarized parent nucleus. This method was successfully applied to structure studies of 29Mg and 30Mg in connection with the physics of the “island of inversion”. In 29Mg, two low-lying levels with intruder configuration were assigned. In 30Mg, coexistence of spherical shape, prolate shape and γ-collectivity was strongly suggested. [ABSTRACT FROM AUTHOR]

A new ISOL-based radioactive nuclear beam (RNB) facility has been constructed as a joint project of the High Energy Accelerator Research Organization (KEK) and the Japan Atomic Energy Research Institute (JAERI) at the Tandem accelerator of the Tokai site of JAERI. It uses heavy-ion linacs and related equipment of the presently closed KEK-RNB facility. Fission fragments with energy from 0.1 to 8 MeV/u will be available at this facility. [Copyright &y& Elsevier]

The performance of the RNB facility at KEK-Tanashi, which is a pilot facility for the E-arena in the KEK–JAERI joint project, is presented. The muonic X-ray spectroscopy of unstable nuclei by combining the RNB with muon-beam from the M-arena in the joint project is introduced. [Copyright &y& Elsevier]

A recoil mass separator was constructed for experiments of nuclear astrophysics using radioactive nuclear beams, and its performance was tested. The observed beam suppression factor around M∼20 was 10−4 when the system was tuned for ΔM=1 heavier ions than beam ions. With a charge state breeding technique, it became 10−8 when the system was tuned for Δq=+1 larger ions than beam ions. [Copyright &y& Elsevier]

Focuses on types of ion sources employed at the isotope separator on-line based radioactive nuclear beam facility at KEK-Tanashi in Japan. Electron cyclotron resonance ion source for ions; Surface ionization-type ion source for ions; Target cell development.

A new multi-reflection time-of-flight mass spectrograph for nuclear mass measurements with high precision has been constructed at the SLOWRI facility at RIKEN-RIBF. We aim to couple this new device to a cryogenic gas cell operated at the BigRIPS facility of RIBF. It is part of the SLOWRI project for slowing down and stopping intense radioactive ion beams provided downstream of RIKEN's superconducting ring cyclotron accelerator. In particular, this device is dedicated to be located at the end of the BigRIPS beam line to access ions that are presently guided to beam dumps during in-beam experiments. In this article the apparatus is described in detail. [ABSTRACT FROM AUTHOR]

Abstract: The excitation function of the 8Li(d, t)7Li reaction was directly measured using 8Li beam irradiating a deuterated polyethylene target at center-of-mass system beam energies () between 0.3 and 1.2 MeV. This is the first cross section measurement of the above reaction below , covering Gamow peaks for of astrophysical interest. A broad resonance-like structure was observed at around . The astrophysical reaction rate deduced from the present result is far larger than the previously reported values estimated from extrapolation of data observed at higher energies, roughly by one order of magnitude at about . [Copyright &y& Elsevier]

Abstract: The excitation function of the 8Li()11B reaction was measured while identifying the final state event by event in the region of using a highly efficient detector system and a low-energy 8Li beam. The results are much improved both in statistics and precisions, and show smaller cross sections than those of previous measurements. A resonance-like structure is found at around . [Copyright &y& Elsevier]

Abstract: Low-energy (1–2MeV/nucleon) radioactive nuclear beams (RNBs) of 8Li, 12B and 16N have been produced through nuclear transfer reactions using a recoil mass separator (RMS) at Japan Atomic Energy Research Institute (JAERI). The contamination of the primary beam to the RNB was investigated quantitatively and was well suppressed. The typical beam intensities of 8Li-, 12B- and 16N-RNB were , and , respectively. Their purities were , and , respectively. [Copyright &y& Elsevier]

Abstract: As an effort to effectively use the short-lived radioactive ion beams to be available in near future at Tokai Radioactive Ion Accelerator Complex, we have developed a radiotracer method for diffusion studies in solids. A test experiment has been performed to measure the diffusion coefficients of Li in the sample of LiAl compound, by using the α-emitting radiotracer of 8Li (T 1/2 =0.84s). The yields of α-particles emitted from diffusing 8Li primarily implanted in the sample have been measured as a function of time under a recurrent time sequence; the implantation of 8Li for 1.5s (beam-on) and subsequent diffusion for 4.5s (beam-off). We have found that the time-dependent yields of the α-particles could be used as a measure of the diffusivity of the tracer in a none-destructive way. By taking into account the experimental conditions, we have simulated the time-dependent α-particle yields for various diffusion coefficients and compared with the experimental ones in order to extract the diffusion coefficients of Li in the sample. The process of the simulations and the comparisons is discussed. [Copyright &y& Elsevier]

We have studied, by a computer simulation, the feasibility of the radiotracer method for diffusion studies using short-lived radioactive nuclear beams as tracers. We have considered two typical examples of radiotracers that will be available in KEK-JAERI RNB facility, 18F (half-life: 1.8 h, β+-emitter) and 8Li (half-life: 0.83 s, α-emitter). The sample is set on a given temperature and irradiated by the tracer beams for a time-duration. In the case of 18F, the serial sectioning technique by the ion-beam-sputtering device is assumed to obtain the concentration-depth profile of the tracer diffused during the irradiation time. In the case of 8Li, the simulation reveals that the time-dependent yields of α particles can be used as a measure of the diffusivity of the tracer in a non-destructive way. The present method could be applied to measure rather large diffusion coefficients of various radiotracers with a short measuring time. [Copyright &y& Elsevier]

For the radioactive nuclear beam facility at KEK Tanashi based on an isotope separator on-line (ISOL), two different types of ion sources are currently employed: a single stage 6.4 GHz ECR and a surface ionization-type ion sources. Several proton-rich radioactive nuclear beams were developed for astrophysical interests. LiF powder target in a water-cooled Cu container is used for the production of Ne isotopes and CaF2 mixed with fine graphite powder for Na isotopes. The ion beams are bunched at the exit of the ion source in order to reduce the beam loss in post acceleration. [Copyright &y& Elsevier]