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Background: The resonance structure in 11 C is particularly of interest with regard to the astrophysical 7 Be(α, γ) reaction, relevant at high temperature, and to the α-cluster structure in 11 C.Purpose: The measurement was to determine unknown resonance parameters for the high excited states of 11 C. In particular, the α decay width can be useful information to discuss α cluster structure in 11 C.Methods: New measurements of the 7 Be+α resonant scattering and the 7 Be(α, p) 10 B reaction in inverse kinematics were performed for center-of-mass energy up to 5.5 MeV, and the resonances at excitation energies of 8.9-12.7 MeV in the compound 11 C nucleus were studied. Inelastic scattering of 7 Be+α and the 7 Be(α, p1) 10 B * reaction were also studied with a simultaneous γ-ray measurement. The measurements were performed at the low-energy RI beam facility CRIB (CNS Radioactive Ion Beam separator) of the Center for Nuclear Study (CNS), the University of Tokyo. Results:We obtained excitation functions of 7 Be(α, α0) 7 Be (elastic scattering), 7 Be(α, α1) 7 Be * (inelastic scattering), 7 Be(α, p0) 10 B, and 7 Be(α, p1) 10 B * . Many resonances including a new one were observed and their parameters were determined by an R-matrix analysis. Conclusions:The resonances we observed possibly enhance the 7 Be(α, γ) reaction rate but in a smaller magnitude than the lower-lying resonances. A new negative-parity cluster band, similar to the one previously suggested in the mirror nucleus 11 B, is proposed.

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