Spectroscopy of ${}^{26}$F to probe proton-neutron forces close to the drip line

Abstract

A long-lived $J^{\pi }=4_1^{+}$ isomer, $T_{1/2}=2.2(1)$ms, has been discovered at 643.4(1) keV in the weakly-bound ${}_9^{26}$F nucleus. It was populated at GANIL in the fragmentation of a ${}^{36}$S beam. It decays by an internal transition to the $J^{\pi }=1_1^{+}$ ground state (82(14)%), by $\beta$-decay to ${}^{26}$Ne, or beta-delayed neutron emission to ${}^{25}$Ne. From the beta-decay studies of the $J^{\pi }=1_1^{+}$ and $J^{\pi }=4_1^{+}$ states, new excited states have been discovered in ${}^{25,26}$Ne. Gathering the measured binding energies of the $J^{\pi }=1_1^{+}-4_1^{+}$ multiplet in ${}_9^{26}$F, we find that the proton-neutron $\pi 0d_{5/2}\nu 0d_{3/2}$ effective force used in shell-model calculations should be reduced to properly account for the weak binding of ${}_9^{26}$F. Microscopic coupled cluster theory calculations using interactions derived from chiral effective field theory are in very good agreement with the energy of the low-lying $1_1^{+},2_1^{+},4_1^{+}$ states in ${}^{26}$F. Including three-body forces and coupling to the continuum effects improve the agreement between experiment and theory as compared to the use of two-body forces only.

5 pages, 3 figures, accepted for publication in Physical Review Letters

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Cited by in corpus (10)

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• Extending the Southern Shore of the Island of Inversion to ${}^{28}$F
• An {\it ab-initio} Gamow shell model approach with a core
• Effective proton-neutron interaction near the drip line from unbound states in ${}^{25,26}$F
• Density matrix renormalization group description of the island of inversion isotopes ${}^{28-33}$F
• Excited states in the neutron-rich nucleus 25F
• Probing nuclear forces beyond the nuclear drip line: The cases of ${}^{16}$F and ${}^{15}$F
• The Core of ${}^{25}$F in the Rotational Model
• Nuclear Structure Studies of Neutron-Rich Nuclei : Astrophysical Implications