Effect of Nuclear Collective Motions on S - and P -Wave Strength Functions

The S- and P-wave strength functions are calculated for a large number of even-even nuclei with A from 34 to 242, using the optical model. The axially- symmetric-rotator model is used for permanently deformed nuclei, and the pure- quadrupole-vibration model for the dynamically deformable nuclei. The inclusion of the collective part of the optical-model potential yields better agreement with the experimental data than the spherical part of the optical potential alone. The model reproduces the experimentally observed structure in the S-wave strength function peaks near A = 55 and 160, and in the P-wave strength function peak near A = 100, but not in the S-wave strength function dip near A = 100. (T.F.H.)