Neutron-unbound states in 25,26F

Abstract

Neutron-unbound states in 25F and 26F were populated via the reactions 9Be(26Ne,24F+n) and 9Be(26Ne,25F+n), respectively. A resonance close to the neutron separation energy in 25F was identified with a decay energy of 28±4 keV. This resonance corresponds to an excited state in 25F at 4249±116 keV assuming it decays to the ground state of 24F. Guided by shell-model calculations, a spin and parity of 1/2- can be assigned to this state. In the spectrum of 26F, which was produced in a nucleon-exchange reaction, there are indications for an excited state with a decay energy of ∼270 keV. © 2011 American Physical Society.