An alternative parameterization of R-matrix theory

Abstract

An alternative parameterization of R -matrix theory is described which is mathematically equivalent to the standard approach, but which has no level shifts. The positions and partial widths of an arbitrary number of levels can thus be easily fixed in an analysis. These alternative parameters can be converted to standard R -matrix parameters by a straightforward matrix diagonalization procedure, and a “level matrix” formulation is possible which allows the collision matrix to be expressed directly in terms of the alternative parameters. The applications to radiative capture reactions and β-delayed particle spectra are briefly discussed.