Astrophysical reaction rate for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="normal">Be</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>9</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>formation within a three-body approach

Casal, J.; Rodríguez‐Gallardo, M.; Arias, J. M.; Thompson, I. J.

doi:10.1103/physrevc.90.044304

Cited by 50 publications

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“…In Ref. [15], we presented a study of 9 Be by using the PS method in hyperspherical coordinates, focusing on the properties of its ground state and its low-lying E1 and M1 continuum. Three-body α + α + n states for total angular momenta j π = 1/2 ± , 3/2 ± , 5/2 ± were described in a THO basis, with effective n-n and α-n interactions as main ingredients.…”

Section: Example: Dipole Response In 9 Be Using Psmentioning

confidence: 99%

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Description of continuum structures in a discrete basis: Three-body resonances and two-nucleon decays

Casal

Rodríguez‐Gallardo

Arias

et al. 2020

SciPost Phys. Proc.

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Weakly bound and unbound three-body nuclei are studied by using the pseudostate method within the hyperspherical formalism. After introducing the theoretical framework, the method is applied first to the 9 Be nucleus, showing a good agreement with the available data for its low-lying dipole response. Then, recent results on the structure and decay of the twoneutron emitters 26 O and 16 Be are presented. In particular, the role of the n-n correlation in shaping their properties is discussed.

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Section: Example: Dipole Response In 9 Be Using Psmentioning

confidence: 99%

“…Details on the calculations for 1/2 + , 3/2 + , 5/2 + , 1/2 − and 5/2 − states can be found in Ref. [15]. In these cases, THO bases with smaller γ values were used to increase the PS density close to the breakup threshold, ensuring a good representation of the low-energy continuum.…”

Section: Example: Dipole Response In 9 Be Using Psmentioning

confidence: 99%

Description of continuum structures in a discrete basis: Three-body resonances and two-nucleon decays

Casal

Rodríguez‐Gallardo

Arias

et al. 2020

SciPost Phys. Proc.

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“…Lately, the PS method in hyperspherical coordinates [2,4] has been successfully applied to describe the structure properties and reaction dynamics of three-body nuclei (e.g. [30][31][32][33][34][35]). This approach, involving a standard eigenvalue problem, is computationally simpler than the calculation of actual continuum states.…”

Section: Introductionmentioning

confidence: 99%

Two-nucleon emitters within a pseudostate method: The case of Be6 and Be16

Casal

2018

Phys. Rev. C

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Background: Since the first experimental observation, two-nucleon radioactivity has gained renewed attention over the past fifteen years. The 6 Be system is the lightest two-proton ground-state emitter, while 16 Be was recently proposed to be the first two-neutron ground-state emitter ever observed. A proper understanding of their properties and decay modes requires a reasonable description of the three-body continuum.Purpose: Study the ground-state properties of 6 Be and 16 Be within a general three-body model and investigate their nucleon-nucleon correlations in the continuum. Method:The pseudostate (PS) method in hyperspherical coordinates, using the analytical transformed harmonic oscillator (THO) basis for three-body systems, is used to construct the 6 Be and 16 Be ground-state wave functions. These resonances are approximated as a stable PS around the known two-nucleon separation energy. Effective core-N potentials, constrained by the available experimental information on the binary subsystems 5 Li and 15 Be, are employed in the calculations. Results:The ground state of 16 Be is found to present a strong dineutron configuration, with the valence neutrons occupying mostly an l = 2 state relative to the core. The results are consistent with previous R-matrix calculations for the actual continuum. The case of 6 Be shows a clear symmetry with respect to its mirror partner, the twoneutron halo 6 He: The diproton configuration is dominant, and the valence protons occupy an l = 1 orbit. Conclusions:The PS method is found to be a suitable tool in describing the properties of unbound core + N + N ground states. For both 16 Be and 6 Be, the results are consistent with previous theoretical studies and confirm the dominant dinucleon configuration. This favors the picture of a correlated two-nucleon emission.

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“…However, these experiments have large uncertainties precisely for the energies close to the threshold, which are the most relevant for the astrophysical reaction rate. The B(E1) distributions could be also calculated, provided that a reliable few-body model is known for the compound nucleus [7,15,16]. Nevertheless, different models may provide different results for the same system.…”

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“…Here, C 3 is a constant depending on the masses and spins of the initial particles. The photodissociation cross section σ γ (ε γ ) of the nucleus A can be expanded into electric and magnetic multipoles, λ, as [12,16] …”

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Determining astrophysical three-body radiative capture reaction rates from inclusive Coulomb break-up measurements

et al. 2016

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A relationship between the Coulomb inclusive break-up probability and the radiative capture reaction rate for weakly bound three-body systems is established. This direct link provides a robust procedure to estimate the reaction rate for nuclei of astrophysical interest by measuring inclusive break-up processes at different energies and angles. This might be an advantageous alternative to the determination of reaction rates from the measurement of B(E1) distributions through exclusive Coulomb break-up experiments. In addition, it provides a reference to assess the validity of different theoretical approaches that have been used to calculate reaction rates. The procedure is applied to 11 Li ( 9 Li + n + n) and 6 He ( 4 He + n + n) three-body systems for which some data exist.DOI: 10.1103/PhysRevC.93.041602Nucleosynthesis occurs in stellar environments, following a complex network of reactions in which heavier nuclei are formed by proton, neutron, or α radiative capture by a lighter nucleus. The knowledge of these radiative capture reaction rates is crucial for the stellar models aiming to describe the evolution in composition, energy production, and temperature structure of different stellar environments (see, for example, Ref.[1] and references therein). The direct experimental measurement of the relevant cross sections is, in principle, possible for two-body reactions [2,3]. In many interesting cases, however, reaction cross sections cannot be measured directly. This may occur if the initial nucleus is short-lived [4] or when the capture process is a three-body reaction [5]. In this case, the inverse reaction to radiative capture, photodissociation, could be measured [4]. Reaction rates are then obtained by integrating the photodissociation cross section for the compound nucleus, weighted with the Maxwell-Boltzmann energy distribution and the relevant phase space factors, from the corresponding energy threshold [6,7]. Direct photodissociation measurements can be done only for stable nuclei, e.g., 12 C [8], sometimes with important discrepancies among different experiments, e.g., 9 Be [5,9]. Thus, for many relevant cases this technique is not feasible (e.g., 17 Ne [10]). In addition, to obtain the reaction rate from experimental photodissociation measurements usually requires, for three-body systems, a sequential description of the formation process, which is questionable at low temperatures if the particles do not have enough energy to populate intermediate resonances [11].At first order, the energy distribution of the photodissociation cross section is determined by the B(E1) distribution, of the compound nucleus, into the continuum of its fragments [12]. Hence, an alternative to obtain this cross section, when the nucleus is short-lived, is to perform exclusive Coulomb breakup experiments at intermediate energies (∼100 MeV/nucleon) on heavy targets, at very forward angles [13,14]. From the exclusive break-up cross section, the B(E1) is extracted * jcasal@us.es assuming Coulomb is dominant at those angles. Howe...

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Astrophysical reaction rate forBe9formation within a three-body approach

Cited by 50 publications

References 50 publications

Description of continuum structures in a discrete basis: Three-body resonances and two-nucleon decays

Description of continuum structures in a discrete basis: Three-body resonances and two-nucleon decays

Two-nucleon emitters within a pseudostate method: The case of Be6 and Be16

Determining astrophysical three-body radiative capture reaction rates from inclusive Coulomb break-up measurements

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