Alternative path for bridging the<i>A</i>= 5, 8 gap in neutron-rich nucleosynthesis scenarios

Diego, R. de; Garrido, E.; Fedorov, D. V.; Jensen, A. S.

doi:10.1088/0954-3899/37/11/115105

Cited by 7 publications

(47 citation statements)

References 14 publications

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“…The rate depends on the capture mechanism. We are here only concerned with three-body capture, but a dense environment would enhance four-body capture processes as discussed in [36]. The overall three-body process is tunneling through a barrier of particles in a temperature distribution of given density.…”

Section: Reaction Mechanismmentioning

confidence: 99%

Two-proton capture on the 68Se nucleus with a new self-consistent cluster model

et al. 2018

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We investigate the two-proton capture reaction of the prominent rapid proton capture waiting point nucleus, 68 Se, that produces the borromean nucleus 70 Kr ( 68 Se+p + p). We apply a recently formulated general model where the core nucleus, 68 Se, is treated in the mean-field approximation and the three-body problem of the two valence protons and the core is solved exactly. The same Skyrme interaction is used to find core-nucleon and core valence-proton interactions. We calculate E2 electromagnetic two-proton dissociation and capture cross sections, and derive the temperature dependent capture rates. We vary the unknown 2 + resonance energy without changing any of the structures computed self-consistently for both core and valence particles. We find rates increasing quickly with temperature below 2 − 4 GK after which we find rates varying by less than a factor of two independent of 2 + resonance energy. The capture mechanism is sequential through the f 5/2 proton-core resonance, but the continuum background contributes significantly.

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Section: Reaction Mechanismmentioning

confidence: 99%

Two-proton capture on the 68Se nucleus with a new self-consistent cluster model

et al. 2018

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“…However, its value oscillates quite a lot from one reaction to another. For instance for the reactions 7 Be(n, p) 7 Li and 14 N(n, p) 14 C the difference in the given S 0 is of almost five orders of magnitude. As a consequence, it is not easy to extract a more or less reliable value to be used in our calculations.…”

Section: A Cross Sectionsmentioning

confidence: 99%

“…Recent calculations have corroborated these conclusions. In [7,8] the possibility of four-body recombination, or particle induced de-excitation (both denominations will be indistinctly used in this work), was pointed out as an alternative mechanism to the spontaneous three-body radiative decay. For densities higher than 10 6 g/cm 3 the four-body recombination dominates, especially for temperatures below 1 GK.…”

Section: Introductionmentioning

confidence: 99%

Direct and sequential four-body recombination rates at low temperatures

Garrido,

Jensen

2021

Preprint

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We investigate four-body nuclear reactions in stellar environments contributing to creation of light nuclei, exemplified by 9 Be and 12 C. The originally assumed process is radiative capture, where nuclear clusters combine into the excited final nucleus and photon emission populates the stable nuclear ground states. Instead, we consider nuclear four-body recombination reactions where a spectator nuclear particle replaces the photon. We first develop the elaborate formalism for both, direct and sequential capture processes, where the decaying three-body resonance is formed without and with population of an intermediate two-body resonance, respectively. To facilitate both calculations and practical applications we parameterize the involved cross sections as done successfully in previous computations of reaction rates. We consider the lowest-lying nuclear states with their dominant contributions at low stellar temperatures. We calculate and compare reaction and production rates for different processes. The direct reaction mechanism dominates by many orders of magnitude at low temperature, where the sequential stepping stones are energetically too expensive to use. At somewhat higher temperatures these two different nuclear four-body mechanisms become comparable. Comparison to radiative three-body capture reveals already formally, but also numerically, that four-body nuclear recombination must dominate for sufficiently high nuclear densities. Numerical values are given for all these rates as function of temperature and density. The relative importance are exhibited.

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“…The inverse process of three-body decay is the recombination of the constituent clusters into the bound state of the nucleus for example by photon emission [8]. The most prominent as well as most studied of these processes is the triple α process leading to 12 C. At low temperature the lowest 0 + resonance, the Hoyle state, is decisive for the triple α rate which proceeds from the 0 + continuum via an E2-transition to the 2 + excited but bound state. The process from the 2 + continuum is dominated by E2transition directly to the 0 + ground state.…”

Section: Rates and Momentum Distributionsmentioning

confidence: 99%

“…7 where Yα = Nα/(Nα + Nn) is the relative fraction of α-particles. Very crudely, 12 C is predominantly created when the neutron density is low, correspondingly 6 He is predominantly created when the neutron density is high, and at intermediate densities the 9 Be creation dominates. The details of when and by how much the different processes contribute is not obvious.…”

Section: Recombination Processesmentioning

confidence: 99%

Few-body Decay and Recombination in Nuclear Astrophysics

et al. 2010

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Three-body continuum problems are investigated for light nuclei of astrophysical relevance. We focus on three-body decays of resonances or recombination via resonances or the continuum background. The concepts of widths, decay mechanisms and dynamic evolution are discussed. We also discuss results for the triple α decay in connection with 2 + resonances and density and temperature dependence rates of recombination into light nuclei from α-particles and neutrons.

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Alternative path for bridging theA= 5, 8 gap in neutron-rich nucleosynthesis scenarios

Cited by 7 publications

References 14 publications

Two-proton capture on the 68Se nucleus with a new self-consistent cluster model

Two-proton capture on the 68Se nucleus with a new self-consistent cluster model

Direct and sequential four-body recombination rates at low temperatures

Few-body Decay and Recombination in Nuclear Astrophysics

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