First investigation of $^{96}$Zr samples enriched by the gas-centrifuge method for the use in rare-decay studies

For the first time, the isotope $^{96}$Zr has been produced by the gas-centrifuge method (enrichment is 88.28% and full mass of $^{96}$Zr is 179.816 g). The level of radionuclide impurities of the samples and thus their suitability for rare-event search have been investigated using three low-background HPGe detectors. The most stringent limit, obtained at sea level, on the half-life of the double beta decay of $^{96}$Zr to the $0^+_1$ excited state (1148 keV) of $^{96}$Mo has been set $T_{1/2}(0\nu+2\nu)>3.9 \times 10^{19}$ yr (90% C.L.).