Allowed DT =1 Gamow-Teller P decay from the Rb 2 ground state to the Sr 3 level at 2.73 MeV is calculated. A one-particleone-hole description of the latter state requires the [2P~&2 (n)2d5&2(n)]~6 component in order to predict the observed logft value of 6.7. The decay rate is extremely sensitive to the amplitude of this term.One of the main reasons for the considerable recent interest in the mass-88 region is the neutronshell closure at the magic number of 50 (completing the 1g, &, shell). This closure forms a basis for the theoretical studies of Sr" by Hughes, ' Sha, stry and Saha, and Shastry. Hughes a,nd Refs. 2 and 3 differ, however, in their treatment of the 38 protons. It is appealing to treat the 2P», proton shell as closed at 38. This doubly magic picture of the Sr" ground state simplifies calculations and is an additional assumption in Refs. 2 and 3. The 3 level at 2. 73 MeV is especially interesting, as it is strongly collective. This state is built up in Ref. 2 out of 14 proton 1p-1h components, and in Ref. 3 three neutron 1p-1h terms are added. (Reference 1 does not consider negativeparity levels. ) Because of these neutron components there is a substantial improvement in the calculated energy of the 3, state and its B(E3) to the ground state. 3 In the present paper we test the importance of these neutron terms by calculating the allowed nT = 1 Gamow-Teller (GT) P decay to the 3 level from the 2 ground state of Rb".
A projection operator method based on the Feshbach doorway approach is developed for low-energy heavy-ion scattering. Applications to "C+"C and "C+"0are made with doorways taken as quasibound or virtual states of the reduced mass coupled to 2+ and 3 vibrations. For "C+"C the elastic differential cross section at 90' c.m. is calculated. For "C+"0 we calculate the ratio of the differential cross section to the Rutherford cross section at a range of angles between 90' and 160' c.m. In both cases the calculations agree well with experiment by producing both the gross and intermediate molecular structure. The conditions under which intermediate structure can be expected are discussed. NUCLEAR REACTIONS C+ C elastic scattering, E =10-30 MeV c.m. , C + i60 elastic scattering, E=18-26 MeV c.m. , projection operator intermediate structure theory, calculated 0 (90') for ' C+ C and 0/0~th (90'-160', increments of 10') for C+ O.
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