Zr/Nb isobar separation experiment for future 93Zr AMS measurement

Zr-93 (t(1/2) = 1.6 Ma) is mostly produced by the main s-process in low-to-intermediate mass AGB stars. Large uncertainty exists in the current Zr-92(n,gamma)Zr-93 Maxwellian Average cross section. This could have significant impact on nucleosynthesis calculations. Large amounts of Zr-93 are also produced in nuclear reactors and pose long-term environmental radioactivity. Hence, measurement of Zr-93 by the AMS is important for both fields above. We report here on progress in the development of AMS method to measure Zr-93. Compared with 98 MeV beam energy, Zr/Nb isobar position separation was improved using 155.2 MeV beam energy and Gas-Filled Magnet. Energy loss measurement with increased beam energy inside the detector indicates that higher beam energy can improve isobar energy loss separation. A chemical procedure to reduce the Nb content in Zr samples has been developed and tested. It reduces the Nb-93 content by a factor of 1000. (C) 2015 Elsevier B.V. All rights reserved.