Decay properties of exotic N

Beta-decay half-lives and [beta]-delayed neutron-emission probabilities of the very neutron-rich nuclei [sup 44]S and [sup 45--47]Cl have been measured. These isotopes, which lie at or close to the [ital N]=28 magic shell, were produced in interactions of a 60 MeV/u [sup 48]Ca beam from GANIL (Grand Accelerateur National d'Ions Lourds) with a [sup 64]Ni target, and were separated by the doubly achromatic spectrometer LISE (Ligne d'Ions Super Epluches). Their decay was studied by a [beta]-[ital n] time correlation measurement. The results are compared to recent model predictions and indicate a rapid weakening of the [ital N]=28 shell effect below [sub 20][sup 48]Ca[sub 28]. The nuclear structure effects reflected in the decay properties of the exotic S and Cl isotopes may be the clue for the astrophysical understanding of the unusual [sup 48]Ca/[sup 46]Ca abundance ratio measured in the solar system as well as the Ca-Ti-Cr anomalies observed in E. King inclusions of the Allende meteorite.