A first attempt to measure 92Nb/93Nb ratios with Accelerator Mass Spectrometry

Abstract An Accelerator Mass Spectrometry (AMS) method for the measurement of the long-lived radionuclide 92 Nb has been established at the HI-13 Tandem Accelerator of the China Institute of Atomic Energy (CIAE). Niobium powder mixed with PbF 2 by a ratio of 1:2 (in mass) was used as the cathode material. Atomic anions of Nb − were extracted from a Cs-beam sputter source. The terminal voltage of the tandem accelerator was 8.5 MV. Nb 13+ ions were selected after terminal foil stripping. A multi-anode gas ionization chamber was used for the particle detection. The total suppression factor of the two major interfering isobars, 92 Zr and 92 Mo, was about 10 3 . A detection limit of about 10 −11 was achieved for 92 Nb/ 93 Nb ratio measurements on a blank sample.