We present a direct measurement of the low-energy 8 Li(p, α) 5 He cross section, using a radioactive 8 Li beam impinging on a thick target. With four beam energies, we cover the energy range between E c.m. = 0.2 and 2.1 MeV. An R-matrix analysis of the data is performed and suggests the existence of two broad overlapping resonances (5/2+ at E c.m. = 1.69 MeV and 7/2 + at E c.m. = 1.76 MeV). At low energies our data are sensitive to the properties of a subthreshold state (E x = 16.67 MeV) and of two resonances above threshold. These resonances were observed in previous experiments. The R-matrix fit confirms spin assignments, and provides partial widths. We propose a new 8 Li(p, α) 5 He reaction rate and briefly discuss its influence in nuclear astrophysics.
Elastic scattering angular distributions of the radioactive weakly bound 7 Be on 27 Al have been measured at energies near the Coulomb barrier. The interaction optical potential is investigated by using different potentials. Total reaction cross sections have also been obtained.
Type-I x-ray bursts can reveal the properties of an accreting neutron star system when compared with astrophysics model calculations. However, model results are sensitive to a handful of uncertain nuclear reaction rates, such as 22 Mgðα;pÞ. We report the first direct measurement of 22 Mgðα;pÞ, performed with the Active Target Time Projection Chamber. The corresponding astrophysical reaction rate is orders of magnitude larger than determined from a previous indirect measurement in a broad temperature range. Our new measurement suggests a less-compact neutron star in the source GS1826-24.
Angular distributions for the elastic scattering of 8 B, 7 Be and 6 Li on 12 C target have been measured at E lab = 25.8 MeV, 18.8 MeV and 12.3 MeV, respectively. The analyses of these angular distributions have been performed in terms of the optical model using Woods-Saxon and double-folding type potentials. The effect of breakup in the elastic scattering of 8 B + 12 C is investigated by performing coupled-channels calculations with the Continuum Discretized Coupled Channel (CDCC) method and cluster-model folding potentials. Total reaction cross sections were deduced from the elastic scattering analysis and compared with published data on elastic scattering of other weakly-and tightly-bound projectiles on 12 C, as a function of energy. With the exception of 4 He and 16 O, the data can be described using a universal function for the reduced cross sections.
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