Measurements of thermonuclear reaction rates for light nuclei with intermediate-energy RI beams

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Using the fast RI beams provided by the RIPS beam course at RIKEN Accelerator Research Facility, we measured several reactions in the hot pp-mode, hot CNO cycle, and rp process. An experiment to test the validity of the Coulomb dissociation method was also performed. The reaction mechanism of the ^8B Coulomb dissociation, which is related to the solar neutrino problem, was investigated.1 The reactions in the hot pp mode, ^8B(p,γ)^9C, ^<11>C(p,γ)^<12>N, and ^<12>N(p,γ)^<13>O, were studied by the Coulomb dissociation. The results were considerably different from what have been used in network calculations for the hot pp mode.2 The Coulomb dissociation of ^<13>N through its 1/2^+ state was studied. From the measured cross section, the radiative width Γ_γ=0.51±0.04 eV was extracted. Its agreement with direct measurements, 0.50±0.04 eV, demonstrates the validity of the method.3 Inelastic scattering of ^<15>O to its 3/2+ state at 6.793 MeV was measured. An upper limit of the transition probability was extracted. The result suggests only small influence of the state to the CNO cycle nuclear burning.4 Coulomb dissociation of ^<23>A1 was measured to determine the ^<22>Mg(p,y)^<23>A1 reaction. The E2 transition to the first excited state, which is considered to be important in the rp-process, was consistent with the evaluation by Wiescher et al., thouth the error is large.5 Cross sections in a wide angular range for the ^8B Coulomb dissociation was analyzed. Together with the data obtained by our GSI experiment at a higher incident energy, the mixture of the E2 transitions was expected to be small.