[en] After a brief review on low-energy RI beam production technology, nuclear astrophysics programs at CNS are presented including a scope of the field in the Wako campus. The CRIB project involves a total development of the whole facility to maximize the low-energy RI beam intensities, including the ion source, the AVF cyclotron and the low-energy RI beam separator CRIB, Some recent nuclear astrophysics experiments performed with the RI beams were discussed, including the measurement of the 14O(α,p)17F reaction, the key stellar reaction for the onset of the high-temperature rp-process. The first experiment performed with a newly installed high-resolution magnetic spectrograph PA of CNS was also presented. Collaboration possibilities for nuclear astrophysics in the RIKEN campus are also touched

[en] Collective motions of β unstable nuclei are interesting because of the uniqueness of shapes different from those of stable nuclei. Measurements of such mode of the giant resonances will supply fruitful of information unaccessible from the previous experiments. In order to access region of the sufficiently high excited energy with small momentum transfer for β unstable nuclei, we newly constructed a magnetic spectrometer for 0 degree scattered recoil particles in inverse kinematics. By means of the spectrometer we measured the H(³⁸S,p^') reaction at forwarding angles including θ_CM=0^o at E_38S=62AMeV as the first challenge of this method. As an experimental result, a bump is confirmed at around E_x=17 MeV. Direct evidences for ISGMR of the β unstable nuclei have not yet been derived. It is hoped that the E0 strength co-exists in the observed bump

[en] We have studied the proton resonance scattering of 7Be by using a pure 7Be beam produced at CRIB (CNS Radioactive Ion Beam separator; CNS stands for Center of Nuclear Study, University of Tokyo). The excitation function of 8B was measured up to the excitation energy of 6.8 MeV, with the thick-target method. The excited states of 8B higher than 3.5 MeV were not known by the past experiments. This proton elastic scattering is also of importance in relation with the 7Be(p,γ)8B reaction, which is a key reaction in the standard solar model

[en] A new measurement of the proton resonance scattering on ⁷Be was performed up to the excitation energy of 6.8 MeV using the low-energy RI beam facility CRIB (CNS Radioactive Ion Beam separator) at the Center for Nuclear Study (CNS) of the University of Tokyo. The excitation function of ⁸B above 3.5 MeV was successfully measured for the first time, providing important information about the reaction rate of ⁷Be(p,γ)⁸B, which is the key reaction in the solar ⁸B neutrino production. For more intensive experimental studies with RI beams, the development of a cryogenic gas target system is ongoing at CNS. In this paper a preliminary result of the ⁷Be experiment and the present status of the development of the target system are presented

[en] Reaction cross sections with various kinds of breakup channels for neutron-rich carbon isotopes ^18-20C and for ⁹Be impinging on a liquid hydrogen target were investigated at 40 MeV/nucleon. The nuclides of interest were produced via projectile fragmentation from a 63 MeV/nucleon ⁴⁰Ar beam and were separated in flight at the RIKEN projectile fragment separator (RIPS). The combination of the large-acceptance superconducting TOF spectrometer, TOMBEE (TOF Mass analyzer for exotic BEam Experiment), with a liquid hydrogen target, CRYPTA (CRYogenic ProTon and Alpha target system), enables simultaneous measurements of several reaction channels: the reaction cross sections (σ_R), individual elemental fragmentation cross sections (σ_ΔZ), charge-changing cross sections (σ_cc), neutron-removal cross sections (σ_-xn), and charge-pickup cross sections (σ_ΔZ+1) for ^19,20C; σ_ΔZ, σ_-xn, and σ_ΔZ+1 for ¹⁸C; and σ_R for ⁹Be. The present σ_R of ⁹Be on proton, σ_R=397±23 mb, measured in the inverse kinematics, was consistent with the previous measurements using proton beams at different laboratories. The σ_R of ¹⁹C and ²⁰C on proton were determined to be σ_R=754±22 mb and σ_R=791±34 mb, respectively. Taking into account the beam energy and target dependence of σ_R, the present σ_R are found to be considerably enhanced compared with those measured at around 1 GeV/nucleon. The σ_ΔZ+1 appears to increase with the mass number of the projectiles, and it significantly contributes to σ_R in the present energy range. The finite-range optical-limit and few-body Glauber model analyses were performed for σ_R to study the nuclear matter density distributions and to derive the relative strength of the s-wave components of the valence neutrons in ¹⁹C and ²⁰C. A neutron halo structure of ¹⁹C is confirmed with an s-wave dominance of the valence neutron when the effect of the charge-pickup reaction is taken into account. The large σ_-n of ¹⁹C and σ_-2n of ²⁰C also support the decoupled structures of ¹⁸C +n and ¹⁸C+2n, respectively. The σ_cc of ¹⁹C and ²⁰C agree with each other within their experimental uncertainties, which might indicate a similar proton density distribution in ¹⁹C and ²⁰C. The σ_ΔZ decreases monotonically without the even-odd effect as the number of removed protons increases.

[en] A new measurement of proton resonance scattering on ⁷Be was performed up to the center-of-mass energy of 6.7 MeV using the low-energy RI beam facility CRIB (CNS Radioactive Ion Beam separator) at the Center for Nuclear Study of University of Tokyo. The excitation function of ⁷Be+p elastic scattering above 3.5 MeV was measured successfully for the first time, providing important information about the resonance structure of the ⁸B nucleus. The resonances are related to the reaction rate of ⁷Be(p,γ)⁸B, which is the key reaction in solar ⁸B neutrino production. Evidence for the presence of two negative parity states is presented. One of them is a 2^- state observed as a broad s-wave resonance, the existence of which had been questionable. Its possible effects on the determination of the astrophysical S-factor of ⁷Be(p,γ)⁸B at solar energy are discussed. The other state had not been observed in previous measurements, and its spin and parity were determined as 1^-