inversion; it can be seen to reproduce the target potential very closely except very near to the nuclear centre in the case of the imaginary tensor component. We have not shown the real tensor component which was only a few percent of the imaginary component nearly everywhere. This small component was reproduced only qualitatively, as expected, since the absolute errors for the real and imaginary $T_{\rm R}$ components were similar in magnitude and comparable to the real $T_{\rm R}$ potential itself. In Figure 1, the dashed line represents the starting potential, zero for the spin-orbit and tensor components. The $S$-matrix elements for the target and inverted potentials are indistinguishable on a graph, corresponding to values of $\sigma$ of roughly $10^{-3}$.

This test shows that the inversion procedure has the capability of revealing quite fine details of the potential as would be required for the kind of applications, discussed in the introduction requiring the inversion of single energy $S$ derived from theory. Such studies might establish, for example, the contribution of specific exchange terms or reaction couplings to the inter-nucleus potential.

Multi-energy inversion at very low energy {#multi}
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At low energies and for light target nuclei, very few partial waves 