Zr–Nb isobar separation experiments for future 93Zr AMS

AMS detection of the rare isotope 93Zr (t1/2 = 1.6 Ma) has application potential in two fields of research: a better determination of the 92Zr(n,γ)93Zr cross section, which is relevant in astrophysical modeling of nucleosynthesis processes, and using this radionuclide as tracer in hydrological and radioactive waste studies. The biggest challenge in measuring 93Zr at natural concentrations is adequate separation from its stable isobar 93Nb. The Nuclear Science Laboratory at University of Notre Dame is developing the capability to measure 93Zr by AMS. Results are reported of first experiments, featuring the combination of a gas-filled magnet with a position-sensitive Parallel Grid Avalanche Counter and a Gas Ionization chamber in this magnet's focal-plane.