Consistent Description of Unbound States Observed in Scattering and Reactions

Abstract

The unbound states of a nucleus C may be studied in elastic scattering A + a -+ C -+ A + a, and in reactions of the type B+b -+ C+c, in which C is an unstable product nucleus. Expressions for the scattering cross sections or phase shifts, and for the dependence of the reaction cross section on Ee, have been derived from R-matrix theory, and it is argued that consistent values of the R-matrix parameters should be used in describing the two types of data. This requirement has been disregarded, however, in a recent paper concerned with the 2+ states of SBe. On the other hand, support for the consistency argument comes from theoretical and experimental work done recently in Canberra on the low-lying states of SHe and sLi.