A long-lived Jπ=41+ isomer, T1/2=2.2(1) ms, has been discovered at 643.4(1) keV in the weakly bound F926 nucleus. It was populated at Grand Accélérateur National d'Ions Lourds in the fragmentation of a S36 beam. It decays by an internal transition to the Jπ=11+ ground state [82(14)%], by β decay to Ne26, or β-delayed neutron emission to Ne25. From the β-decay studies of the Jπ=11+ and Jπ=41+ states, new excited states have been discovered in Ne25,26. Gathering the measured binding energies of the Jπ=11+-41+ multiplet in F926, we find that the proton-neutron π0d5/2ν0d3/2 effective force used in shell-model calculations should be reduced to properly account for the weak binding of F926. 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 11+, 21+, 41+ states in F26. 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.
ASJC Scopus subject areas
- Physics and Astronomy(all)