Abstract
A search for continuum levels in with a large O()+α] parentage has been conducted using both resonant and direct production processes. The differential cross section for the (α,() reaction has been measured at 13 to 26 angles for bombarding energies from =10.2 to 18 MeV, mostly in 25 keV steps. Events leading to the first excited state in were identified by requiring the coincident observation of an α particle and an electron or positron from the internal pair decay of the first excited state. Amplitudes of individual partial waves were extracted from the data by parametrizing the angular distributions in terms of the complex zeros of the scattering amplitudes. An R-matrix analysis of the data reveals a = level at =13.1 MeV with a spectroscopic factor >63%.
Several individual levels, a region of overlapping = levels from =13.69 to 14.93 MeV and a region of = levels from =16.73 to 18.73 MeV, have also been analyzed in detail. Branching ratios of levels to the first excited state in have been measured by populating the levels with the reaction C,α and observing their subsequent α decay to the state of . A = level at =15.16 MeV and a = level at =18.54 MeV, which had previously been suggested as members of a rotational band based on the = level in at =12.44 MeV are shown to have small values of , arguing against this identification.
- Received 23 September 1991
DOI:https://doi.org/10.1103/PhysRevC.45.576
©1992 American Physical Society