利用α关联衰变链鉴别新同位素_(107)^(265)Bh

Identification of the New Isotope _(107)^(265)Bh by α Correlated Decay Chains

主要介绍了合成和鉴别107号元素的新同位素265Bh的实验装置、实验方法以及实验结果.目标核265Bh是由能量为135MeV的26Mg离子轰击243Am靶,通过融合蒸发反应而产生.反应产物首先由He jet系统传输到装有数个探测器对的转轮收集测量系统,然后依靠母子核遗传关系通过观察新同位素和它们已知子核261Db和257Lr之间的α衰变的关联,来实现对新核素的鉴别.实验测得265Bh的α衰变能量为(9.24±0.05)MeV, 半衰期为0.94+0.70-0.31s.从该实验得出的265Bh的α衰变能量和半寿命能够与理论预言一致.

The experimental set-up, methods and results on the synthesis and identification of the new isotope 265 107 Bh are presented in this paper. The new isotope was produced by the complete fusion-evaporation reaction of 243 Am with 135MeV 26 Mgbombardement at the Sector Focus Cyclotron of Heavy Ion Research Facility Lanzhou. The reaction products were transported and collected using helium-jet technique and a set of rotating wheel system. The identification of the new isotope was made by observing of correlated α-particle decays chain between the new isotope 265 Bh and its 261 Db and 257 Lr daughters. A total of 8 correlated decay events of 265 Bh and 4 decay events of 264 Bh were observed. The new nuclide 265 Bh has a half-life of 0.94 +0.70 -0.31 s and decays by alpha-particle emission with decay energy of E α=(9.24±0.05)MeV. The half-life and α decay energy of 265 Bh from this experiment are consistent with theoretical predictions.