Search for excited states in ${}^{25}$O

Abstract

Theoretical calculations suggest the presence of low-lying excited states in ${}^{25}$O. Previous experimental searches by means of proton knockout on ${}^{26}$F produced no evidence for such excitations. We search for excited states in ${}^{25}$O using the ${}^{24}\text{O}(d,p){}^{25}\text{O}$ reaction. The theoretical analysis of excited states in unbound ${}^{25,27}$O is based on the configuration interaction approach that accounts for couplings to the scattering continuum. We use invariant-mass spectroscopy to measure neutron-unbound states in ${}^{25}$O. For the theoretical approach, we use the complex-energy Gamow Shell Model and Density Matrix Renormalization Group method with a finite-range two-body interaction optimized to the bound states and resonances of ${}^{23-26}$O, assuming a core of ${}^{22}$O. We predict energies, decay widths, and asymptotic normalization coefficients. Our calculations in a large $spdf$ space predict several low-lying excited states in ${}^{25}$O of positive and negative parity, and we obtain an experimental limit on the relative cross section of a possible $J^{\pi }={1/2}^{+}$ state with respect to the ground-state of ${}^{25}$O at ${\sigma }_{1/2+}/{\sigma }_{g.s.}=0.25_{-0.25}^{+1.0}$. We also discuss how the observation of negative parity states in ${}^{25}$O could guide the search for the low-lying negative parity states in ${}^{27}$O. Previous experiments based on the proton knockout of ${}^{26}$F suffered from the low cross sections for the population of excited states in ${}^{25}$O because of low spectroscopic factors. In this respect, neutron transfer reactions carry more promise.

References in corpus (25)

• Mean-field description of ground-state properties of drip-line nuclei: Pairing and continuum effects
• Nuclear Energy Density Optimization
• Shell Model in the Complex Energy Plane
• Continuum effects and three-nucleon forces in neutron-rich oxygen isotopes
• Shell Structure of Exotic Nuclei
• Evidence for the ground-state resonance of 26O
• Beyond the Neutron Drip-Line: The Unbound Oxygen Isotopes 25O and 26O
• Generic strong coupling behavior of Cooper pairs in the surface of superfluid nuclei
• Density matrix renormalization group approach for many-body open quantum systems
• Study of two-neutron radioactivity in the decay of 26O
• Emergent properties of nuclei from ab initio coupled-cluster calculations
• Living on the edge of stability, the limits of the nuclear landscape
• Continuum effects in neutron-drip-line oxygen isotopes
• Persistent contribution of unbound quasiparticles to the pair correlation in continuum Skyrme-Hartree-Fock-Bogoliubov approach
• Correlated two-neutron emission in the decay of unbound nucleus 26O
• Density matrix renormalization group approach to two-fluid open many-fermion systems
• Gamow shell-model calculations of drip-line oxygen isotopes
• Pairing-induced localization of the particle continuum in weakly bound nuclei
• Asymptotic normalization coefficients and continuum coupling in mirror nuclei
• Spectroscopy of neutron-unbound ${}^{27,28}$F
• Decay dynamics of the unbound ${}^{25}$O and ${}^{26}$O nuclei
• A New Efficient Method of Hartree-Fock-Bogoliubov Calculation for Weakly Bound Nuclei
• Reconstruction of nuclear charged fragment trajectories from a large gap sweeper magnet
• Two-Neutron Sequential Decay of ${}^{24}$O
• Are there good probes for the di-neutron correlation in light neutron-rich nuclei?

Cited by in corpus (11)

• Non-Empirical Interactions for the Nuclear Shell Model: An Update
• Ab initio calculations of low-energy nuclear scattering using confining potential traps
• Unbound spectra of neutron-rich oxygen isotopes predicted by the Gamow shell model
• Energy Spectrum of Neutron-Rich Helium Isotopes: Complex Made Simple
• Chiral three-nucleon force and continuum for dripline nuclei and beyond
• Description of proton-rich nuclei in the $A\sim 20$ region with the Gamow shell model
• Gamow Shell Model description of Li isotopes and their mirror partners
• Density matrix renormalization group description of the island of inversion isotopes ${}^{28-33}$F
• Calculation of the Thomas-Ehrman shift in ${}^{16}$F and ${}^{15}$O(p,p) cross section with the Gamow shell model
• Deep excursion beyond the proton dripline. II. Toward the limits of existence of nuclear structure
• The Gamow-state description of the decay energy spectrum of neutron-unbound ${}^{25}$O