Symmetric fission properties of neutron-rich transfermium nuclei

中性子過剰超フェルミウム原子核の対称核分裂の性質

浅井 雅人  

Asai, Masato

中性子過剰超フェルミウム原子核の対称核分裂の性質を調べるため、Fm, Md, Lrの自発核分裂片を測定した。これらの原子核は、原子力機構タンデム加速器施設において、OビームとEs標的を用いた多核子移行反応及び重イオン核融合-粒子蒸発反応Cm(N,4n)Lrにより合成した。核反応生成物はオンライン同位体分離装置ISOLを用いて質量分離し、4組のシリコン半導体検出器を用いて2つの核分裂片の運動エネルギーを同時計数測定した。得られた核分裂片の質量分布と全運動エネルギー分布から、中性子過剰超フェルミウム原子核における対称核分裂の詳しい性質を明らかにした。

Symmetric fission properties of neutron-rich transfermium nuclei have been studied through the measurements of spontaneous fission fragments of Fm, Md, and Lr. These nuclei were produced in the multinucleon transfer reactions with the O beam and the Es target, and in the fusion-evaporation reaction of Cm(N,4n)Lr at the JAEA tandem accelerator facility. The reaction products were mass-separated with the on-line isotope separator (ISOL), and the kinetic energies of spontaneous-fission fragments were measured with 4 pairs of Si semiconductor detectors. The deduced fission-fragment mass distributions and total kinetic energy distributions have revealed the detailed properties of symmetric fissions in this neutron-rich Fm and transfermium nuclei.