Anomalously strong absorption of neutron partial waves by the nuclear optical potential is investigated in detail. More than 100 cases of anomalously strong absorption are found over the entire Periodic Table of stable nuclei in the range of energy 0–80 MeV and orbital angular momentum 0–13. A study of the S matrix in the complex-k plane reveals two different types of anomalous absorption. Discussions are given on systematics of the anomaly, its wave function, its relation to the strong absorption in the heavy-ion scattering and to the so-called unstable bound states, and on the experimental observation of the anomaly, which could be a new test of the optical potential.

• Received 23 July 1984

DOI:https://doi.org/10.1103/PhysRevC.31.400