open access

https://doi.org/10.14943/doctoral.k15278

https://hdl.handle.net/2115/89586

中性子過剰なBeとB同位体におけるクラスター形成

英語

2023-03-23

Hokkaido University

45p

This dissertation is based on [1]: (H. Motoki, Y. Suzuki, T. Kawai, and M. Kimura, Progress of Theoretical and Experimental Physics 2022(11), 113D01 (2022) https://doi.org/10.1093/ptep/ptac145).Background:Recently, experiments performed using the (p, pα) reactions have revealed anegative correlation between the α cluster formation and neutron number in Sn isotopes, showing a trend opposite to that predicted theoretically in Be and B isotopes. Although the observed charge radii of the Be and B isotopes suggest the formation of clusters as the neutron drip-line is approached, these radii themselves are not a physical quantity that can directly probe the cluster structure. Purpose: I directly investigate the cluster formation in Be and B isotopes as the neutron drip-line is approached to elucidate the effect of excess neutrons for the possibilities of 6He and 8He clustering as well as α clustering. Method: All nuclei are described by antisymmetrized molecular dynamics (AMD) plus generator coordinate method (GCM) framework. The cluster formations are directly analyzed by the spectroscopic factors (S-factor) of 6He and 8He clusters as well as α clusters using the Laplace expansion method. Results: Sum of the S-factors, i.e. S(α), S(6He), and S(8He), increases as the neutron drip-line approaches although S(α) decreases. This behavior might be correlated with the enhancement of clustering which is analyzed by the intrinsic proton density distributions. Conclusions: The results indicate that the excess neutrons contribute to yield 6He and 8He clusters as well as α clusters. The decrease in S(α) toward the neutron dripline in Be and B isotopes is due to considering only the ground state of the residual nuclei, meaning that it does not indicate that α cluster formation is not increased. Thus, S(α) is not enough to estimate the enhancement of clustering in Be and B isotopes.

2023-03-23

甲第15278号

博士(理学)

(主査) 教授 木村 真明, 教授 岡本 崇, 准教授 平林 義治, 客員准教授 堀内 渉

理学院（宇宙理学専攻）

博士論文

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