SEARCH FOR HIGHLY DEFORMED SHAPE ISOMERS IN SI-28, MG-24 AND NE-20 LINKED BY SUCCESSIVE ALPHA-DECAYS

Measurements of the C-12(O-16,Ne-20 alpha)alpha, C-12(O-16,alpha alpha )Ne-20, C-12(O-16,Be-8)Ne-20 and C-12(O-16, O-16 alpha)Be-8 reactions have been performed at E-c.m. = 27.0 MeV. For decays proceeding throug h resonant states in the intermediate Mg-24 nucleus, angular correlati on measurements have enabled spin assignments to be made and the domin ant entrance channel angular momentum to be determined. The results ar e inconsistent with recent similar experiments which were interpreted as arising from successive alpha-decays from deformed shape isomeric s tates in Si-28 and Mg-24. (C) 1998 Elsevier Science B.V.