First trap-assisted decay spectroscopy of the $$^{81}$$Ge ground state

Abstract The $$\beta $$ β -delayed $$\gamma γ spectroscopy of $$^{81}$$ 81 As has been performed using a purified beam Ge $$(9/2^+)$$ ( 9 / 2 + ) ground state at the Ion Guide Isotope Separator On-Line facility (IGISOL). $$^+$$ ions were produced proton-induced fission $$^{232}$$ 232 Th and selected with double Penning trap JYFLTRAP for post-trap decay measurements. low-spin $$(1/2^+)$$ 1 isomeric-state $$^{81m}\hbox {Ge}^+$$ m Ge not observed in products. intrinsic half-life determined as $$T_{1/2}=6.4(2)~\hbox {s}$$ T = 6.4 s , which is significantly shorter than literature value. A new level scheme built compared to shell-model calculations.