Investigation of spatial manifestation of α clusters in 16O via α-transfer reactions.

Abstract Recently, we have determined surface distributions of α clusters in the ground state of Ne 20 from α -transfer cross sections, without investigating the properties of its excited states. In this paper we extend our comprehension of α -cluster structures in excited states of nuclei through reaction studies. In particular we focus on O 16 , for which attention has been paid to advances of structure theory and assignment regarding 4 + -resonance states. We study the surface manifestation of the α -cluster states in both the ground and excited states of O 16 from the analysis of the α -transfer reaction C 12 (Li 6 , d) 16 O. The α -transfer reaction is described by the distorted-wave Born approximation. We test two microscopic wave functions as an input of reaction calculations. Then a phenomenological potential model is introduced to clarify the correspondence between cluster-wave functions and transfer-cross sections. Surface peaks of the α -wave function of O 16 (0 +) are sensitively probed by transfer-cross sections at forward angles, while it remains unclear how we trace the surface behavior of O 16 (4 +) from the cross sections. From inspection of the cross sections at forward angles, we are able to specify that the α -cluster structure in the 0 1 + and 0 2 + states prominently manifests itself at the radii ∼4 and ∼4.5 fm, respectively. It is remarkable that the 4 1 + state has the C 12 + α -cluster component with the surface peak at the radius ∼4 or outer, whereas the C 12 + α -cluster component in the 4 2 + state is found not to be dominant. The 4 2 + state is difficult to be interpreted by a simple potential model assuming the C 12 + α configuration only. [ABSTRACT FROM AUTHOR]