Investigation of the ββ decay of 96Zr to excited states in 96Mo

The two-neutrino mode of double beta decay (2νββ) of 96Zr is investigated both theoretically and experimentally. The calculations, using the quasiparticle random phase approximation approach, show that for 96Zr the detection of 2νββ transitions to the two first excited states in the daughter nuclide will be possible in the very near future. On the experimental side, new, most stringent limits on half-lives for the double beta decay of 96Zr to excited states in 96Mo have been obtained with a 430 cm3 'well-type' germanium detector. They range between 5x1019 and 8x1019 years (90% CL). (author)