Helmholtz Institute Mainz, 55099 Mainz, Germany and GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
Phys Rev Lett. 2014 May 2;112(17):172501. doi: 10.1103/PhysRevLett.112.172501. Epub 2014 May 1.
The superheavy element with atomic number Z=117 was produced as an evaporation residue in the (48)Ca+(249)Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-μs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope (294)117 and its decay products. A hitherto unknown α-decay branch in (270)Db (Z = 105) was observed, which populated the new isotope (266)Lr (Z = 103). The identification of the long-lived (T(1/2) = 1.0(-0.4)(+1.9) h) α-emitter (270)Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an "island of stability."
德国达姆施塔特重离子研究中心的 TASCA 充气反冲分离器上，通过（48）Ca+（249）Bk 融合反应，成功合成了原子序数为 Z=117 的超重元素。利用可以测量半衰期在亚微秒到几天之间的单个原子核衰变的探测装置，研究了蒸发残余物及其α衰变产物的放射性衰变。鉴定出了两条包含七个α衰变和一个自发裂变的衰变链，并将其分配给同位素（294）117 和其衰变产物。观察到了（270）Db（Z=105）中一个此前未知的α衰变分支，其生成了新的同位素（266）Lr（Z=103）。长寿命（T1/2=1.0(-0.4)(+1.9) h）α发射体（270）Db 的识别，是朝着观察位于“稳定岛”上的更重超重元素的重要一步。
