We report on the measurement of the ^{7}Be(n,p)^{7}Li cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n_TOF facility at CERN. This reaction plays a key role in the lithium yield of the big bang nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and they showed a large discrepancy between each other. The measurement was performed with a Si telescope and a high-purity sample produced by implantation of a ^{7}Be ion beam at the ISOLDE facility at CERN. While a significantly higher cross section is found at low energy, relative to current evaluations, in the region of BBN interest, the present results are consistent with the values inferred from the time-reversal ^{7}Li(p,n)^{7}Be reaction, thus yielding only a relatively minor improvement on the so-called cosmological lithium problem. The relevance of these results on the near-threshold neutron production in the p+^{7}Li reaction is also discussed.

The 40 Ca(α, γ ) 44 Ti reaction is believed to be the main production channel for the radioactive nuclide 44 Ti in core-collapse supernovae. Radiation from decaying 44 Ti has been observed so far for two supernova remnants, and precise knowledge of the 44 Ti production rate may help improve supernova models. The 40 Ca(α, γ ) 44 Ti astrophysical reaction rate is determined by a number of narrow resonances. Here, the resonance triplet at E α = 4497, 4510, and 4523 keV is studied both by activation, using an underground laboratory for the γ counting, and by in-beam γ spectrometry. The target properties are determined by elastic recoil detection analysis and by nuclear reactions. The strengths of the three resonances are determined to be ωγ = (0.92 ± 0.20), (6.2 ± 0.5), and (1.32 ± 0.24) eV, respectively, a factor of 2 more precise than before. The strengths of this resonance triplet may be used in future works as a point of reference. In addition, the present new data directly affect the astrophysical reaction rate at relatively high temperatures (above 3.5 GK).

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The strength of the Ep = 1.842 MeV resonance in the 40 Ca(p,γ) 41 Sc reaction is determined with two different methods: First, by an absolute strength measurement using calcium hydroxide targets, and second, relative to the well-determined strength of the resonance triplet at Eα = 4.5 MeV in the 40 Ca(α,γ) 44 Ti reaction. The present new value of ωγ = (0.192 ± 0.017) eV is 37% (equivalent to 3.5σ) higher than the evaluated literature value. In addition, the ratio of the strengths of the 1.842 MeV 40 Ca(p,γ) 41 Sc and 4.5 MeV 40 Ca(α,γ) 44 Ti resonances has been determined to be 0.0229 ± 0.0018. The newly corrected strength of the 1.842-MeV resonance can be used in the future as a normalization point for experiments with calcium targets.