Speaker
Description
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 [1], 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 [2], with a level structure corresponding to the rotation-aligned coupling limit of the Particle Rotor Model (PRM) [3].
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. [1].
PRM predictions for some spectroscopic observables will also be presented and discussed in the context of a Coulomb Excitation experiment approved at RIKEN [4]. 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.
[1] P. Doornenbal, et al., Phys. Rev. C95, 041301(R) (2017).
[2] A. O. Macchiavelli, et al., Phys. Lett. B775, 160 (2017).
[3] F. S. Stephens, Rev. Mod. Physics , 47, 43 (1975).
[4] H. L. Crawford, et al., RIBF164 proposal (2017).
