Cross section predictions for hydrostatic and explosive burning

Descouvemont, Pierre; Rauscher, T.

doi:10.1016/j.nuclphysa.2004.10.024

Cited by 41 publications

(41 citation statements)

References 114 publications

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“…Even if data is available, it can only provide a measure of σ µ = ν σ µν and thus does not provide the required σ * . Depending on the number of resonances in the Gamow window [2], one has to consider direct reactions, the influence of few resonances, or an average over many resonances [35]. Here, we want to focus on the latter and on direct capture.…”

Section: B Relevant Reaction Theorymentioning

confidence: 99%

“…A nucleon or nucleon group is directly transferred from the projectile to the final state without excitation of any other nucleons in the system [35,37,38]. This mechanism will dominate at very high interaction energies where the compound nucleus formation is suppressed due to the short interaction timescale and at low energies in the absence of resonances, again suppressing the formation of a compound nucleus.…”

Section: B Relevant Reaction Theorymentioning

confidence: 99%

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Large-scale prediction of the parity distribution in the nuclear level density and application to astrophysical reaction rates

et al. 2007

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A generalized method to calculate the excitation-energy dependent parity ratio in the nuclear level density is presented, using the assumption of Poisson distributed independent quasi particles combined with BCS occupation numbers. It is found that it is crucial to employ a sufficiently large model space to allow excitations both from low-lying shells and to higher shells beyond a single major shell. Parity ratios are only found to equilibrate above at least 5-10 MeV of excitation energy. Furthermore, an overshooting effect close to major shells is found where the parity opposite to the ground state parity may dominate across a range of several MeV before the parity ratio finally equilibrates. The method is suited for large-scale calculations as needed, for example, in astrophysical applications. Parity distributions were computed for all nuclei from the proton dripline to the neutron dripline and from Ne up to Bi. These results were then used to recalculate astrophysical reaction rates in a Hauser-Feshbach statistical model. Although certain transitions can be considerably enhanced or suppressed, the impact on astrophysically relevant reactions remains limited, mainly due to the thermal population of target states in stellar reaction rates.

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Section: B Relevant Reaction Theorymentioning

confidence: 99%

Section: B Relevant Reaction Theorymentioning

confidence: 99%

Large-scale prediction of the parity distribution in the nuclear level density and application to astrophysical reaction rates

et al. 2007

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“…Current radioactive ion beam facilities are still limited to a region around stability and often reactions cannot be measured unless either the target or residual nucleus is long-lived or stable. Because of the low interaction energies in astrophysically relevant reactions, the statistical Hauser-Feshbach model [1] can be used to predict reaction rates provided the level density in the compound nucleus is sufficiently high [2]. The model requires input based on nuclear structure physics, such as nuclear masses and deformations, optical model potentials, and nuclear level densities.…”

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confidence: 99%

Astrophysical relevance ofγtransition energies

Rauscher

2008

Phys. Rev. C

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The relevant γ energy range is explicitly identified where additional γ strength has to be located for having an impact on astrophysically relevant reactions. It is shown that folding the energy dependences of the transmission coefficients and the level density leads to maximal contributions for γ energies of 2 ≤ Eγ ≤ 4 unless quantum selection rules allow isolated states to contribute. Under this condition, electric dipole transitions dominate. These findings allow to more accurately judge the relevance of modifications of the γ strength for astrophysics.

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“…Transmission functions for particles are usually predicted by utilizing the optical model [1]. This requires an optical potential with real and imaginary parts that are, in principle, dependent on the type of the projectile, target mass, and projectile energy.…”

Section: Optical Potentialsmentioning

confidence: 99%

“…Due to the comparatively low energies (E 10 MeV for charged projectiles and E 1 MeV for neutrons) relevant in astrophysical plasmas, mainly three reaction mechanisms are important [1]: compound, resonant, and direct reactions. In principle, both resonant and direct mechanism may contribute to the reaction cross section although one of them is negligible in most cases.…”

Section: Introductionmentioning

confidence: 99%