Nuclear rotation in the continuum

Abstract

$\text{Background:}$ Atomic nuclei often exhibit collective rotational-like behavior in highly excited states, well above the particle emission threshold. What determines the existence of collective motion in the continuum region, is not fully understood. $\text{Purpose:}$ In this work, by studying the collective rotation of the positive-parity deformed configurations of the one-neutron halo nucleus ${}^{11}$Be, we assess different mechanisms that stabilize collective behavior beyond the limits of particle stability. $\text{Method:}$ To solve a particle-plus-core problem, we employ a non-adiabatic coupled-channel formalism and the Berggren single-particle ensemble, which explicitly contains bound states, narrow resonances, and the scattering continuum. We study the valence-neutron density in the intrinsic rotor frame to assess the validity of the adiabatic approach as the excitation energy increases. $\text{Results:}$ We demonstrate that collective rotation of the ground band of ${}^{11}$Be is stabilized by (i) the fact that the $\ell =0$ one-neutron decay channel is closed, and (ii) the angular momentum alignment, which increases the parentage of high-$\ell$ components at high spins; both effects act in concert to decrease decay widths of ground-state band members. This is not the case for higher-lying states of ${}^{11}$Be, where the $\ell =0$ neutron-decay channel is open and often dominates. $\text{Conclusion:}$ We demonstrate that long-lived collective states can exist at high excitation energy in weakly bound neutron drip-line nuclei such as ${}^{11}$Be.

References in corpus (7)

• Shell Model in the Complex Energy Plane
• Evidence for Triangular D_3h Symmetry in 12C
• Emergence of rotational bands in ab initio no-core configuration interaction calculations of the Be isotopes
• Quantum Monte Carlo calculations of electromagnetic transitions in 8Be with meson-exchange currents derived from chiral effective field theory
• Open problems in nuclear structure near drip lines
• Bound and resonance states of the dipolar anion of hydrogen cyanide: competition between threshold effects and rotation in an open quantum system
• Broad resonances and beta-decay

Cited by in corpus (19)

• Microscopic Clustering in Light Nuclei
• Non-Empirical Interactions for the Nuclear Shell Model: An Update
• Can Ab Initio Theory Explain the Phenomenon of Parity Inversion in ${}^{11}$Be?
• From bound states to the continuum
• Can tetraneutron be a narrow resonance?
• Rotating deformed halo nuclei and shape decoupling effects
• First observation of unbound ${}^{11}$O, the mirror of the halo nucleus ${}^{11}$Li
• Structures and decay properties of extremely proton-rich nuclei ${}^{11,12}$O
• Rotational excitations in near neutron-drip line nuclei: the birth and death of particle-bound rotational bands and the extension of nuclear landscape beyond spin zero neutron drip line
• Single-particle and collective motion in unbound deformed ${}^{39}\text{Mg}$
• Energy Spectrum of Neutron-Rich Helium Isotopes: Complex Made Simple
• Structure and reactions of 11Be: many-body basis for single-neutron halo
• Structure of the exotic ${}^9$He nucleus from the no-core shell model with continuum
• Weak binding effects on the structure of ${}^{40}$Mg
• Rotational bands beyond the Elliott model
• Resonant spectra of multipole-bound anions
• Perspectives on few-body cluster structures in exotic nuclei
• A Vision for the Science of Rare Isotopes
• Fast rotation of nuclei with extreme isospin in the vicinity of neutron and proton drip lines