STRUCTURE AND REACTIONS OF THE BE-12,BE-14 NUCLEI

The phenomenon of s-wave intruder orbits is examined for the Be-12 and Be-14 isotopes. Although Be-11 has an s-wave ground state, a three-bo dy model of two neutrons + Be-10 can only reproduce the properties of Be-12 if the valence neutrons occupy mainly the (p(1/2))(2) configurat ion with about 25% admixture of (sd)(2) configurations, For Be-14, the possibility of low-lying s-wave states in Be-13 means that a wide ran ge of models are compatible with the existing radius and momentum meas urements, though some s admixture is necessary for binding. We show wh ich kinds of momentum and Coulomb breakup measurements will be necessa ry to elucidate the structure of the Be-14 halo.