Elastic and inelastic scattering of 30 MeV polarized protons from 90Zr, 92Zr, and 92Mo

Abstract

Analyzing powers and cross sections have been measured for elastic and inelastic scattering of 30 MeV polarized protons from 90Zr, 92Zr, and 92Mo. The experimental results are analyzed in terms of the coupled-channels formalism using the vibrational model. The best fits for the analyzing power for all the nuclei are obtained by using the full Thomas form for the spin–orbit potential. These calculations give a very good description for both the cross sections and the analyzing powers of the low-lying 2+, 3−, 5−, and 4+ states in 90Zr, 92Zr, and 92Mo. Only a small increase of the spin–orbit deformation over the central deformation (βLS/βcentral = 1.5) is needed to reproduce the data; this is contrary to the situation at lower energy where a large increase of this ratio was required (Raynal). Some differences between the 90Zr–92Mo data (which are similar) and the 92Zr data have also been observed; this is, however, in agreement with previous results at lower energy. Microscopic model calculations with tensor and spin–orbit components included in the projectile–target interaction (real interaction), and with an exact treatment of 'knock-on' exchange, have also been performed for the 2+ states in these nuclei. These calculations give a very good agreement with the cross sections but a rather poor agreement with the analyzing powers even when a complex interaction is used.