“First trap-assisted decay spectroscopy of the 81Ge ground state”

The 𝛽-delayed 𝛾 spectroscopy of 81As has been performed using a purified beam of 81Ge (9/2+) ground state at the Ion Guide Isotope Separator On-Line facility (IGISOL). The 81Ge+ ions were produced using proton-induced fission of 232Th and selected with the double Penning trap JYFLTRAP for the post-trap decay spectroscopy measurements. The low-spin (1/2+) isomeric-state ions 81𝑚Ge+ were not observed in the fission products. The intrinsic half-life of the 81Ge ground state has been determined as 𝑇1/2=6.4(2) s, which is significantly shorter than the literature value. A new level scheme of 81As has been built and is compared to shell-model calculations.