The question of the number and origin of isomeric states in ${}^{256}\mathrm{Rf}$ arose from two independent experiments but remained unanswered for a decade. To shed light on this puzzle, we studied isomeric decay in ${}^{256}\mathrm{Rf}$ by measuring conversion electrons with fast fully digital electronics. ${}^{256}\mathrm{Rf}$ was produced in the fusion-evaporation reactions of ${}^{50}\mathrm{Ti}+{}^{207}\mathrm{Pb}$ and ${}^{50}\mathrm{Ti}+{}^{208}\mathrm{Pb}$ at the gas-filled recoil separator TransActinide Separator and Chemistry Apparatus. Among a total of 120 decays of ${}^{256}\mathrm{Rf}$, we detected 22 and 12 decays proceeding through one and two isomeric states. Half-lives of the low- and higher-lying states were assigned to be $T_{1/2}={14}_{-4}^{+6}$ and ${10}_{-3}^{+5}\mu \mathrm{s}$, respectively. Population rates of these isomeric states were estimated to be $\approx 18\%$ and $>10\%$, which are similar to those for two-quasiparticle $K$ isomeric states in this region of nuclei. The results, thus, confirm an earlier claim on the existence of multiple $K$ isomeric states in ${}^{256}\mathrm{Rf}$ and show their population rates are as high as in No isotopes. Suggestively, $K$ remains a good quantum number in isotopes of heavier elements like Sg and Hs, where yet unknown high-$K$ isomeric states still could exist. The present experimental results demonstrate that the “triggerless” measurement guarantees an efficient detection of delayed conversion electron signals. Thus, it is a very efficient method for the identification of isomeric states in experiments with one nucleus-at-a-time production rates.

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Rf256 中的异构状态

异构体状态的数量和起源问题 ${}^{256}\mathrm{射频}$来自两个独立的实验，但十年来仍未得到解答。为了阐明这个难题，我们研究了异构体衰变${}^{256}\mathrm{射频}$ 通过使用快速全数字电子设备测量转换电子。 ${}^{256}\mathrm{射频}$ 是在熔融蒸发反应中产生的 ${}^{50}钛+{}^{207}铅$ 和 ${}^{50}钛+{}^{208}铅$在充气反冲分离器 TransActinide Separator and Chemistry Apparatus。在总共 120 个衰变中${}^{256}\mathrm{射频}$，我们检测到 22 和 12 衰变通过一个和两个异构体状态进行。低地和高地状态的半衰期被指定为${吨}_{1/2}={14}_{-4}^{+6}$ 和 ${10}_{-3}^{+5}\mu \mathrm{秒}$， 分别。这些异构状态的人口率估计为$\approx 18\%$ 和 $>10\%$, 类似于两个准粒子 $钾$核的这个区域的异构状态。因此，结果证实了早先关于存在多个$钾$ 异构体状态 ${}^{256}\mathrm{射频}$并显示它们的人口率与无同位素一样高。暗示，$钾$ 在 Sg 和 Hs 等较重元素的同位素中仍然是一个很好的量子数，其中未知的高$钾$异构状态仍然可能存在。目前的实验结果表明，“无触发”测量保证了延迟转换电子信号的有效检测。因此，它是一种非常有效的方法，用于在具有一个核一次生产率的实验中鉴定异构状态。