The elastic and inelastic scattering of n particles by ¹i and Pb has been investigated at an incident energy of 139 MeV. The elastic cross sections have been analyzed in terms of the optical model using a six-parameter Woods-Saxon potential. The data for 5 ¹i are sufficient to eliminate the discrete ambiguity in the strength of the potential; the single potential which fits the data has a well depth of 116 MeV and a volume integral J/4A of 298 MeV fm3.For Pb the discrete ambiguity could not be resolved. This outcome is consistent with recently developed criteria for experimental data necessary to resolve the discrete ambiguity. A discussion of the discrete ambiguity, in particular the A dependence, is given, and it is shown that measurements at higher energies are required to resolve the ambiguity for Pb. The inelastic cross sections for transitions to the 1.45-MeV (J~=2+), 2.46-MeV (4+), 4.47-MeV (3 ) states in 58Ni and the 2.62-MeV (3 ) state in Pb have been analyzed with distortedwave Born-approximation (DWBA) calculations using collective-model form factors. The results are consistent with previous analyses of lower-energy data.

The differential elastic-scattering cross sections of 1-BeV protons on hydrogen, helium, carbon, and oxygen have been measured. The nuclear data exhibit diffractionlike structure associated with the multiple scattering of protons by nucleons inside the nuclei. The experimental technique provides a new and powerful method for studying nucleon-nucleon correlations inside the nucleus.

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