<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>R</mml:mi></mml:mrow></mml:math>-matrix and dynamical model calculations of three-body resonance decay widths

Bartlett, Amy; Tostevin, J. A.; Thompson, I. J.

doi:10.1103/physrevc.78.054603

Cited by 7 publications

(8 citation statements)

References 24 publications

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“…It has been shown (e.g., in Ref. [48]), that the width can also be estimated from the internal norm of the scattering wave functions. These energy distributions, however, are not available within the present pseudostate approach, so an estimation of the width in this context requires additional considerations.…”

Section: Bementioning

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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Section: Bementioning

confidence: 99%

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

Casal

2018

Phys. Rev. C

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“…It is not clear whether this should be done coherently or incoherently as discussed in detail in Refs. [8,9].…”

Section: A Three-body Formulationmentioning

confidence: 99%

“…The use of R-matrix theory for calculating the width of three-body decays has been discussed recently [8,9]. The purpose of the present article is to establish validity conditions and predictive power for R-matrix calculations of decay spectra of three-body decays, when can it be used, and that predictions are reliable.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the large binding energy of the α particle the threshold for one or more α particles is often low in light nuclei and therefore breakup to final states of three α particles or nucleons is experimentally easy to reach, e.g. breakup of 12 C(3α), 9 Be(2αn), 9 B(2αp), 6 He(α2n), 6 Li(αpn), 6 Be(α2p). The number of such investigations is increasing due to the many new and upgraded operating facilities using unstable beams.…”

Section: Introductionmentioning

confidence: 99%

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Three-body decays andR-matrix analyses

et al. 2009

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The R-matrix simulation of three-body decays is investigated as function of available Q value and the energy and width of the intermediate two-body resonance. We use three α-decaying unnatural parity states of 12 C for illustration. The energy distributions are shown to be sensitive to the parameters when the two-body energy is significantly smaller than Q and the width is smaller than about 0.5 MeV. The sequential decay inherent in the R-matrix formalism can then be distinguished from direct decay. We provide conditions for the validity of R-matrix analyses. We compare with full three-body computations of the same energy distributions where we also attempt to distinguish between sequential and direct decays. The results give a good reproduction of available experimental data and are consistent with the conclusions from R-matrix analyses. Nodes in the momentum distributions arise from angular momentum and parity conservation. Combined with symmetry requirements this constrains the momentum distributions significantly in some cases. Effects of interactions and decay mechanisms can only be seen in the remaining behavior as, e.g., additional nodes related to nodes in the coordinate wave function at large distance.

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“…The energies are measured from the three-alpha threshold. two different procedures can lead to sometimes very different values for the resonance widths [38]. In Table II, + states we proceed in a similar way.…”

Section: B 12 C Spectrummentioning

confidence: 99%

Three-body bremsstrahlung and the rotational character of theC12spectrum

2015

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The electric quadrupole transitions between 0 + , 2 + , and 4 + states in 12 C are investigated in a 3α model. The three-body wave functions are obtained by means of the hyperspherical adiabatic expansion method, and the continuum is discretized by imposing a box boundary condition. Corresponding expressions for the continuum three-body (3α) bremsstrahlung and photon dissociation cross sections are derived and computed for two different α-α potentials. The available experimental energy dependence is reproduced and a series of other cross sections are predicted. The transition strengths are defined and derived from the cross sections, and compared to schematic rotational model predictions. The computed properties of the 12 C resonances suggest that the two lowest bands are made, respectively, by the states {0 For the second band, the transitions are also consistent with a rotational pattern, but with the three alphas in an aligned arrangement.

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R-matrix and dynamical model calculations of three-body resonance decay widths

Cited by 7 publications

References 24 publications

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

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

Three-body decays andR-matrix analyses

Three-body bremsstrahlung and the rotational character of theC12spectrum

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