Evidence for particle stability of $^{31}$F and particle instability of $^{25}$N and $^{28}$O
Résumé
The neutron drip line up to fluorine has been investigated by the projectile fragmentation of a 94.1A MeV /sup 40/Ar beam at the fragment separator RIPS at RIKEN. A new neutron-rich isotope, /sup 31/F, has been observed for the first time while clear evidence for the particle instability of /sup 24,25/N, /sup 27,28/O and /sup 30/F has been obtained. The sudden change in stability from oxygen to fluorine may demonstrate the onset of deformation for the neutron-rich fluorine isotopes.