Spin excitations in light nuclei: Effect of projectile energy.

Abstract

We present a microscopic analysis of the nuclear spin response to protonexcitation by examining the specific case of the/sup 40/Ca(/ital p/rvec //,/ital p/rvec // ') reaction. Recent resultsindicate that the spin-flip probability decreases with an increase in theincident proton energy from /ital E//sub /ital p//=319 to 800 MeV but otherwisemaintains the essential features of an enhancement at high excitation and aquenching at low excitation. We show that this feature is consistent withnuclear structure effects and is not likely to depend on the particular choiceof proton beam energy. We also suggest that the decrease in spin-flip crosssection with increasing /ital E//sub /ital p// is directly linked to the energydependence of the /ital t/-matrix coefficients and conclude by presentingpredictions for cross sections at lower incident proton energy.