6533b857fe1ef96bd12b38f9

RESEARCH PRODUCT

Search for Electron-Capture Delayed Fission in the New Isotope Md244

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The electron-capture decay followed by a prompt fission process was searched for in the hitherto unknown most neutron-deficient Md isotope with mass number 244. Alpha decay with $\ensuremath{\alpha}$-particle energies of 8.73--8.86 MeV and with a half-life of ${0.30}_{\ensuremath{-}0.09}^{+0.19}\text{ }\text{ }\mathrm{s}$ was assigned to $^{244}\mathrm{Md}$. No fission event with a similar half-life potentially originating from spontaneous fissioning of the short-lived electron-capture decay daughter $^{244}\mathrm{Fm}$ was observed, which results in an upper limit of 0.14 for the electron-capture branching of $^{244}\mathrm{Md}$. Two groups of fission events with half-lives of ${0.9}_{\ensuremath{-}0.3}^{+0.6}\text{ }\text{ }\mathrm{ms}$ and ${5}_{\ensuremath{-}2}^{+3}\text{ }\text{ }\mathrm{ms}$ were observed. The ${0.9}_{\ensuremath{-}0.3}^{+0.6}\text{ }\text{ }\mathrm{ms}$ activity was assigned to originate from the decay of $^{245}\mathrm{Md}$. The origin of eight fission events resulting in a half-life of ${5}_{\ensuremath{-}2}^{+3}\text{ }\text{ }\mathrm{ms}$ could not be unambiguously identified within the present data while the possible explanation has to invoke previously unseen physics cases.