The Boundary Condition Parameter in R-Matrix Theory

Abstract

In the general R-matrix theory of nuclear reactions, all measurable quantities such as the cross sections scc' should be independent of the choice of the boundary condition parameters Bc although the values of the level parameters E? and ??c depend on the Bc. For applications involving only a finite number of levels ?, it is not obvious that this is still the case as completeness arguments can no longer be used. It is shown here that scc' can be made independent of the choice Bc of for any finite number of levels and any number of channels, and the resulting formulae giving the dependence of E? and ??c on Bc are derived. An application is made to the pair of 5/2- levels of 7Li near 7 MeV excitation.