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arXiv · 1809.04980

Investigation of spatial manifestation of $α$ clusters in $^{16}$O via $α$-transfer reactions

Tokuro Fukui·Yoshiko Kanada-En'yo·Kazuyuki Ogata·Tadahiro Suhara·Yasutaka Taniguchi
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Abstract

Recently, we have determined surface distributions of $α$ clusters in the ground state of $^{20}\mathrm{Ne}$ 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 $^{16}\mathrm{O}$, 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 $^{16}\mathrm{O}$ from the analysis of the $α$-transfer reaction $^{12}\mathrm{C}(^6\mathrm{Li},d)^{16}\mathrm{O}$. 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 $^{16}\mathrm{O}(0^+)$ are sensitively probed by transfer-cross sections at forward angles, while it remains unclear how we trace the surface behavior of $^{16}\mathrm{O}(4^+)$ from the cross sections. We are able to specify that the $α$-cluster structure in the $0_1^+$ and $0_2^+$ states prominently manifests itself at the radii $\sim 4$ and $\sim 4.5$~fm, respectively. It is remarkable that the $4_1^+$ state has the $^{12}\mathrm{C}+α$-cluster component with the surface peak at the radius $\sim 4$ or outer, whereas the $^{12}\mathrm{C}+α$-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 $^{12}\mathrm{C}+α$ configuration only.

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Tokuro Fukui, Yoshiko Kanada-En'yo, Kazuyuki Ogata, Tadahiro Suhara, Yasutaka Taniguchi. 2019-04-12. Investigation of spatial manifestation of $α$ clusters in $^{16}$O via $α$-transfer reactions. https://doi.org/10.1016/j.nuclphysa.2018.12.024

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