Probing the nuclide 180W for neutrinoless double-electron capture exploration

The mass difference of the nuclides 180W and 180Hf has been measured with the Penning-trap mass spectrometer SHIPTRAP to investigate 180W as a possible candidate for the search for neutrinoless double-electron capture. The Qϵϵ-value was measured to 143.20(27) keV. This value in combination with the calculations of the atomic electron wave functions and other parameters results in a half-life of the 0+→0+ ground-state to ground-state double-electron capture transition of approximately 5×1027years/2〈mϵϵ[eV]〉.