Recent results from RIKEN/RIBF on the low-lying level structure of 29F, and state of the art Shell Model calculations using the SDPF-M effective interaction , suggest the extension of the N=20 Island of Inversion to the Z=9 Fluorine isotopes.
In this work we discuss the low-lying excitation spectrum of 29F in terms of a collective picture , with a level structure corresponding to the rotation-aligned coupling limit of the Particle Rotor Model (PRM) .
The Coriolis coupling effects on the proton d5/2 Nilsson multiplet give rise to a (favored) decoupled band, with its 5/2+ bandhead naturally emerging as the ground state. The first excited state corresponds to the anti-aligned 1/2+ configuration at an energy that depends directly on the core E(2+).
We find a consistent solution at a deformation of ε ~ 0.17, corresponding to an excitation energy of the 2+ in 28O at ~2.4 MeV, in line with the conclusions reached in Ref. .
PRM predictions for some spectroscopic observables will also be presented and discussed in the context of a Coulomb Excitation experiment approved at RIKEN . If similar energetics and coupling conditions persist, a πd5/2 x νf7/2 double-decoupled structure in 30F is predicted with a 6- ground state.
- This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract no DE-AC02-05CH11231.
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