Degeneracy at 1871 keV in ^{112}Cd and implications for neutrinoless double electron capture

High-statistics beta-decay measurements of Ag-112 and In-112 were performed to study the structure of the Cd-112 nucleus. The precise energies of the doublet of levels at 1871 keV, for which the 0(+) member has been suggested as a possible daughter state following neutrinoless double electron capture of Sn-112, were determined to be 1871.137(72) keV (0(4)(+) level) and 1870.743(54) keV (4(2)(+) level). The nature of the 0(4)(+) level, required for the calculation of the nuclear matrix element that would be needed to extract a neutrino mass from neutrinoless double electron capture to this state, is suggested to be of intruder origin.