New limit for the half-life of double beta decay of 94Zr to the first excited state of 94Mo

Abstract

Neutrinoless Double Beta Decay is a phenomenon of fundamental interest in particle physics. The decay rates of double beta decay transitions to the excited states can provide input for Nuclear Transition Matrix Element calculations for the relevant two neutrino double beta decay process. It can be useful as supplementary information for the calculation of Nuclear Transition Matrix Element for the neutrinoless double beta decay process. In the present work, double beta decay of 94Zr to the 2+ 1 excited state of 94Mo at 871.1 keV is studied using a low background ∼ 230 cm3 HPGe detector. No evidence of this decay was found with a 232 g.y exposure of natural Zirconium. The lower half-life limit obtained for the double beta decay of 94Zr to the 2+ 1 excited state of 94Mo is T1/2(0ν + 2ν) > 3.4 × 1019 y at 90% C.L., an improvement by a factor of ∼ 4 over the existing experimental limit at 90% C.L. The sensitivity is estimated to be T1/2(0ν + 2ν) > 2.0 × 1019 y at 90% C.L. using the Feldman-Cousins method.