Stability and synthesis of superheavy elements; Fighting the battle against fission - Example of No

超重元素の安定性と合成; 核分裂との闘い - Noの例

Lopez-Martens, A.*; Henning, G.*; Khoo, T. L.*; Seweryniak, D.*; Alcorta, M.*; 浅井 雅人  ; Back, B. B.*; Bertone, P. F.*; Boilley, D.*; Carpenter, M. P.*; Chiara, C. J.*; Chowdhury, P.*; Gall, B.*; Greenlees, P. T.*; Gurdal, G.*; Hauschild, K.*; Heinz, A.*; Hoffman, C. R.*; Janssens, R. V. F.*; Karpov, A. V.*; Kay, B. P.*; Kondev, F. G.*; Lakshmi, S.*; Lauritsen, T.*; Lister, C. J.*; McCutchan, E. A.*; Nair, C.*; Piot, J.*; Potterveld, D.*; Reiter, P.*; Rowley, N.*; Rogers, A. M.*; Zhu, S.*

Lopez-Martens, A.*; Henning, G.*; Khoo, T. L.*; Seweryniak, D.*; Alcorta, M.*; Asai, Masato; Back, B. B.*; Bertone, P. F.*; Boilley, D.*; Carpenter, M. P.*; Chiara, C. J.*; Chowdhury, P.*; Gall, B.*; Greenlees, P. T.*; Gurdal, G.*; Hauschild, K.*; Heinz, A.*; Hoffman, C. R.*; Janssens, R. V. F.*; Karpov, A. V.*; Kay, B. P.*; Kondev, F. G.*; Lakshmi, S.*; Lauritsen, T.*; Lister, C. J.*; McCutchan, E. A.*; Nair, C.*; Piot, J.*; Potterveld, D.*; Reiter, P.*; Rowley, N.*; Rogers, A. M.*; Zhu, S.*

原子番号が100を超える原子核の核分裂障壁の高さとその角運動量依存性を初めて測定した。核分裂による崩壊が優勢となり始める励起エネルギーを決定できる初期分布法という方法をNoの測定に適用した。Noの核分裂障壁はスピンゼロにおいて6.6MeVと決定された。このことは、Noが原子核の殻効果によって強く安定化されていることを示している。

Fission barrier height and its angular-momentum dependence have been measured for the first time in the nucleus with the atomic number greater than 100. The entry distribution method, which can determine the excitation energy at which fission starts to dominate the decay process, was applied to No. The fission barrier of No was found to be 6.6 MeV at zero spin, indicating that the No is strongly stabilized by the nuclear shell effects.