郭俊盛,袁双贵,靳根明.超重新核素²⁵⁹Db的合成及²³⁰Ac β-缓发裂变的确证[J].中国科学院院刊,2002,(2):108-111.

超重新核素²⁵⁹Db的合成及²³⁰Ac β-缓发裂变的确证

Synthesis of New Super-heavy Nuclide ²⁵⁹Db and Determination of β-delayed Fission Precursor ²³⁰Ac

郭俊盛
近代物理研究所 兰州730000
Guo Junsheng
Institute of Modern Physics, CAS, 730000 Lanzhou
袁双贵
近代物理研究所 兰州730000
Yuan Shuanggui
Institute of Modern Physics, CAS, 730000 Lanzhou
靳根明
近代物理研究所 兰州730000
Jin Genming
Institute of Modern Physics, CAS, 730000 Lanzhou

         超重核;衰变;β-缓发裂变;化学分离

        利用HIRFL提供的　2 2 Ne束流轰击锕系放射性靶　2 4 1Am ,通过熔合 蒸发反应生成了 10 5号元素的一些同位素 ,经对其衰变特性的测量和母子体关系的分析 ,确定已合成了 10 5号元素的新同位素　2 59Db ,其α衰变能Eα=9.4 7MeV ,半衰期为 0 .5 1秒。在　18O轰击Th的实验中 ,产物经化学分离后用已预先处理过的云母探测器及γ探测器同时测量 ,测得两例碎片径迹 ,经分析认定它是来自　2 3 0 Ac的缓发裂变 ,从而确定　2 3 0 Ac是缓发裂变先驱核 ,其缓发裂变几率为 (1.19± 0 .85 )× 10 -8。

        After measuring the decay properties of the produced element by bombardment of 241 Am with 22 Ne beam at HIRFL and analyzing their mother daughter relations,it shows that a new nuclide 259 Db with E α =9.47 MeV and T 1/2 =0.51s has been synthesized. The reaction production of 18 O + 232 Th was separated chemically and then measured by pre etched mica foil and γ detector at the same time in a lead shielded low background room. Two fission fragment tracks observed in the mica foil have been determined to come from 230 Ac delayed fission, and a delayed fission probability of (1.19±0.85)×10 -8 for 230 Ac is obtained.