Cauldrons in the Cosmos

Asymptotic normalization coefficients and radiative widths

“…Because the interference between the internal radiative width amplitude (calculated in the singleparticle model) and the real part of the channel radiative width amplitude in the case under consideration is constructive, the channel radiative width Γ 1/2 γ 3/2 (ch) = 0.36 ± 0.07 eV provides a stronger low limit for the total radiative width then Eq. This transition plays an important role in the radiative capture 14 N + p → 15 O + γ, which is the bottleneck reaction in the CNO cycle [21][22][23]. A subthreshold resonance is a bound state, which is close to the threshold.…”

Alpha clustering and the stellar nucleosynthesis of carbon

“…The α-α scattering and the ground-state properties of 8 Be as well as the bound and resonant states in 12 C, which are relevant for the triple-alpha process are discussed in [2].…”

“…Therefore, the 8 Be is almost in equilibrium with the α-particles. During the life time of 8 Be a third α-particle is captured by the reaction 8 Be(α,γ) 12 C. The first step depends sensitively on the properties of the 8 Be ground-state, whereas the reaction rate of the second step is mainly a consequence of the properties of the 0 + 2 state in 12 C, which lies just above the threshold of the 8 Be(α,γ) 12 C reaction.…”

Lithium and boron burning S(E)-factor measurements at astrophysical energies via the Trojan Horse Method

“…However, direct measurements of nuclear reactions at astrophysical energies are usually difficult to perform. In such situations the corresponding Gamow window lies at energies at which the cross-section values decrease exponentially to the nano-or-picobarn regime because of the Coulomb barrier between the interacting nuclei ( [4]). Thus the energy region of interest for astrophysics is usually explored by means of extrapolation procedures on the bare-nucleus S(E) b -factor because it smoothly varies with the energy, thus removing the exponential drop of the cross section ( [4]).…”