超重元素合成の理論—揺動散逸理論の観点から—

Takahiro Wada; 和田隆宏

doi:10.3769/radioisotopes.67.255

超重元素合成の理論—揺動散逸理論の観点から—Nuclear Theory for The Synthesis of Superheavy Elements—From The View Point of Fluctuation-dissipation Theory—

和田隆宏Takahiro Wada

関西大学システム理工学部物理・応用物理学科Department of Pure and Applied Physics, Faculty of Engineering Science, Kansai University ◇ 564–8680　大阪府吹田市山手町3–3–35 ◇ 3–3–35 Yamatecho, Suita, Osaka 564–8680, Japan

発行日：2018年6月15日Published: June 15, 2018

原子番号113番の元素がニホニウムと命名され，同時に118番までの元素名が確定した。これら超重元素の合成反応は，強いクーロン斥力の下での融合・分裂反応であり，準核分裂など従来の核反応理論では重要視されていなかった新しい特徴を持っている。本稿では，揺動散逸理論の観点から合成反応について述べる。核分裂障壁への殻補正エネルギーの寄与や融合過程のランジュバン方程式による取り扱いについて解説する。

The element with Z=113 has been named as Nihonium and the names of the new elements up to Z=118 have been determined. Synthesis of these superheavy elements is a fusion–fission process under a very strong Coulomb repulsion. It revealed many new aspects of nuclear reactions such as quasi-fission which were not carefully studied so far. In this manuscript, we describe the processes of the synthesis of supreheavy elements from the view point of fluctuation-dissipation theory. We apply Langevin equation to calculate the competition between the formation of superheavy compound nuclei and the decay through the quasi-fission reaction. We also discuss the importance of the shell-correction energy in the survival process.

Key words: superheavy element; fusion–fission reaction; fluctuation-dissipation theory; Langevin equation; shell correction energy

RADIOISOTOPES

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超重元素合成の理論—揺動散逸理論の観点から—Nuclear Theory for The Synthesis of Superheavy Elements—From The View Point of Fluctuation-dissipation Theory—