Unexpected Strong Pair Correlations in Excited0+States of Actinide Nuclei

Abstract

The ($p,t$) reaction has been studied with 17-MeV protons on targets of ${\mathrm{Th}}^{230}$, ${\mathrm{U}}^{234,236,238}$, and ${\mathrm{Pu}}^{242,244}$. The results indicate unexpectedly strong $l=0\mathrm{}$ transitions to states at about 900-keV excitation. Their cross sections are approximately 15% of the ground-state transitions; this percentage does not change appreciably with neutron number. This result, together with other available evidence, seems to suggest a simple and rather stable collective mode which has not yet emerged from any theoretical calculations.