Identifying structures in the continuum: Application to ${}^{16}$Be

Abstract

The population and decay of two-nucleon resonances offer exciting new opportunities to explore dripline phenomena. The understanding of these systems requires a solid description of the three-body (core+N+N) continuum. The identification of a state with resonant character from the background of non-resonant continuum states in the same energy range poses a theoretical challenge. It is the purpose of this work to establish a robust theoretical framework to identify and characterize three-body resonances in a discrete basis. A resonance operator is proposed, which describes the sensitivity to changes in the potential. Resonances are then identified from the lowest eigenstates of the resonance operator. The operator is diagonalized in a basis of Hamiltonian pseudostates, built within the hyperspherical harmonics formalism using the analytical THO basis. The energy and width of the resonance are determined from its time dependence. The method is applied to 16Be in a 14Be+n+n model. An effective core+n potential, fitted to the available information on the subsystem 15Be, is employed. The 0+ ground state resonance of 16Be presents a strong dineutron configuration, which favors the picture of a correlated two-neutron emission. Fitting the three body interaction to the experimental two-neutron separation energy |S2n|=1.35(10) MeV, the computed width is Gamma(0+)=0.16 MeV. From the same Hamiltonian, a 2+ resonance is also predicted with E_r(2+)=2.42 MeV and Gamma(2+)=0.40 MeV. The dineutron configuration and the computed 0+ width are consistent with previous R-matrix calculations for the true three-body continuum. The extracted values of the resonance energy and width converge with the size of the pseudostate basis and are robust under changes in the basis parameters. This supports the reliability of the method in describing the properties of unbound core+N+N systems in a discrete basis.

arXiv comment11 pages, 14 figures. Accepted as PRC

References in corpus (19)

• Radioactive decays at limits of nuclear stability
• FaCE: a tool for Three Body Faddeev calculations with core excitation
• Can Ab Initio Theory Explain the Phenomenon of Parity Inversion in ${}^{11}$Be?
• New treatment of breakup continuum in the method of continuum discretized coupled channels
• Four-body continuum-discretized coupled-channels calculations
• Astrophysical reaction rate for ${}^9$Be formation within a three-body approach
• Three-body continuum discretization in a basis of transformed harmonic oscillator states
• Reaction models to probe the structure of light exotic nuclei
• Relative production rates of ${}^6$He, ${}^9$Be, ${}^{12}$C in astrophysical environments
• Analytical transformed harmonic oscillator basis for three-body nuclei of astrophysical interest: Application to 6He
• ${}^4\mathrm{He}$+$n$+$n$ continuum within an ab initio framework
• Low-temperature triple-alpha rate in a full three-body model
• ${}^9$Be elastic scattering on ${}^{208}$Pb and ${}^{27}$Al within a four-body reaction framework
• Exploring continuum structures with a pseudo-state basis
• Dependence of two-proton radioactivity on nuclear pairing models
• Two-nucleon emitters within a pseudostate method: The case of ${}^6$Be and ${}^{16}$Be
• Three-body model for the two-neutron decay of ${}^{16}$Be
• Radiative capture reaction for ${}^{17}$Ne formation within a full three-body model
• Coulomb breakup of 22C in a four-body model

Cited by in corpus (10)

• Coupled-channels calculations for nuclear reactions: from exotic nuclei to superheavy elements
• Two-proton emission and related phenomena
• Toward emulating nuclear reactions using eigenvector continuation
• Electric dipole response of low-lying excitations in the two-neutron halo nucleus ${}^{29}$F
• The ${}^{29}$F nucleus as a lighthouse on the coast of the island of inversion
• Practical method for decomposing discretized breakup cross sections into components of each channel
• Description of continuum structures in a discrete basis: Three-body resonances and two-nucleon decays
• Dineutron in the $2_1^{+}$ state of ${}^6$He
• Comparison of Pauli projection and supersymetric transformation methods for three-body nuclear structure and reactions
• Two-nucleon emitters within a pseudostate approach