A search for the radiative neutrinoless double-electron capture of 58Ni

Abstract

A search for the radiative neutrinoless double-electron capture with single γ-ray emission has been performed in 58Ni. Gamma radiation from a nickel sample in natural isotope composition was measured for with an ultra-low background HPGe detector in the Felsenkeller underground laboratory in Dresden, Germany. A new lower half-life limit of yr ( CL) was obtained for this decay mode. This half-life limit is two orders of magnitude higher than the existing limit for 58Ni and among the best half-life limits for neutrinoless double-electron capture decays.