Inadequacy of the coupled-channels born approximation for explaining anomalous rare-earth (d,t) transitions

A CCBA (coupled-channels Born approximation) analysis is used to study the importance of multistep processes involving quadrupole inelastic excitations in producing anomalously shaped angular distributions for rare-earth (d,t) transitions. The CCBA results are compatible with DWBA (distorted-Wave Born approximation) results in the cases where the DWBA works well and tend to improve agreement for the anomalous transitions -but the overall agreement is still rather poor and additional improvements in the reaction calculations will be needed to understand the anomalous transitions.