CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Studies on proton and alpha resonance scatterings, (α,p) reactions, and other types of measurements (β-decay lifetimes etc.) have been performed using RI beams at CRIB, motivated by interests on astrophysical reactions and exotic nuclear structure. Among the studies at CRIB, the measurement of 7 Li+α resonant scattering is presented.

The 30 S(α, p) reaction is considered to be important in the nuclear trajectory to higher mass in type I X-ray bursts. The reaction flow encounters a bottleneck at 30 S, owing to the competition of photo-disintegration with further proton capture, and because the half-life of this isotope is on the order of the burst rise timescale. Different burst simulations by various researchers indicate the (α, p) reaction may bypass this waiting point, depending on the stellar reaction rate, which has not previously been measured experimentally, and the structure of the compound nucleus 34 Ar is not well understood above the alpha-threshold. The 30 S(α, p) reaction could explain rare bolometrically double-peaked burst profiles, appears to make a considerable contribution to the overall energy generation, and affects the neutron star crustal composition for the recurrent inertia required in burst models to reproduce astronomical observations. Using a low-energy 30 S radioactive ion beam and an active target technique (a helium gas mixture serves as both a target gas and a detector fill gas), we acquired data on both alpha elastic scattering of 30 S as well as the 30 S(α, p) reaction simultaneously at relevant energies for X-ray bursts. We present for the first time the status of the data analysis and the preliminary results of this research.

We reported new results on the first direct measurement of the 11 C(α, p) 14 N reaction, which is considered to be part of an alternative pathway responsible for the nucleosynthesis from the pp-chain region to the CNO cycle region in high-temperature hydrogen burning processes. We successfully measured the excitation functions at stellar energies both for (α, p 0 ), (α, p 1 ) and (α, p 2 ) separately for the first time. 11th Symposium on Nuclei in the Cosmos

A radio-isotope of 26g Al (where g is expressing the ground state) is known as a -ray emitter spreading in the Milky Way galaxy. Since the half-life is only 7.2 × 10 5 year this is the obvious evidence of ongoing nucleosynthesis in our galaxy. This isotope is also known as an origin of abundance-anomaly of 26 Mg observed in meteorites. Therefore, investigations of production rates for the 26g Al are quite important for the nucleosynthesis occurring in massive star, classical nova and super nova. Although, there is still some uncertainties in the nuclear structure of 26 Si which is located at the bypass sequence producing the isomeric state 26m Al (where m is expressing the metastable 1 st excited state). For the comprehensive understanding of the nuclear reaction rate to produce the 26g Al, we have done -ray spectroscopy to investigate the level structure for the 26 Si. We confirmed the presence of a recently proposed level located just above the proton threshold. Furthermore, as a result of the gamma-ray angular correlation measurements we could assign the spin of this level as 0 + .

The 29 P(p, γ) 30 S reaction rate strongly affects explosive hydrogen burning in classical novae and type I X-ray bursts, and depends on the structure of proton unbound 30 S states. The rate in the temperature characteristic of nucleosynthesis in novae and X-ray bursts had been previously predicted to be dominated by two low-lying, unobserved, J π = 3 + and 2 + resonances above the proton threshold in 30 S. Since then, two states have been found at 4699(6) keV and 4814(3) keV, which were tentatively assigned to be the 3 + and 2 + states, respectively. To confirm the existence of these two levels and their energies, the structure of 30 S was investigated via an in-beam γ-ray spectroscopy experiment using the 28 Si( 3 He, nγ) 30 S reaction at University of Tsukuba Tandem Accelerator Complex in Japan. This work describes the experimental setup and presents the preliminary results.11th Symposium on Nuclei in the Cosmos