Deducing the asymptotic normalization constant of the 2+ subthreshold state in 16O from 12C + alpha elastic scattering

Abstract

R-matrix analyses of the 12C + alpha elastic-scattering phase shifts deduced from a recent high-precision measurement of the differential cross sections are performed. The l=0 phase shifts constrain the R-matrix radius a around 5.85 fm, while the l=2 phase shifts lead to a strong constrain neither on a nor on the asymptotic normalization constant C of the 2+ subthreshold state (except for a loose upper limit). This contradicts previous R-matrix analyses of the 12C + alpha elastic scattering and explains the incompatibility between values of C obtained in these analyses.

Comments: 6 pages, 4 figures, proceedings of the 8th International Conference on Clustering Aspects of Nuclear Structure and Dynamics, Nara (Japan), November 24-29, 2003