The new extended HVE 1 MV multi-element AMS system for low background installed at the Aarhus AMS Dating Centre

Aarhus University, Department of Physics and Astronomy has installed a new multi-element AMS system at its AMS C-14 Dating Centre. It is manufactured by High Voltage Engineering Europa B.V. and based on a 1 MV Tandetron accelerator with a dual gas system (Ar and He) for the terminal stripper. The injector is equipped with two independently operating ion sources and a 120 degree bouncer magnet with high resolution and a bending power of 340 amu at 35 keV, supporting the measurements of actinides. The high-energy (HE) spectrometer features a degrader foil for isobar suppression and a second HE magnet for suppression of ions scattered in the HE ESA, which ensures very low detection limits. The control system supports different methods for isotope switching: traditional fast bouncing, adjusting the Hall-probe controlled magnet fields (for, e.g., H-3), or changing the complete set of operation parameters (e.g., for actinides). During the on-site acceptance tests, the following background levels were measured: <10(-16) for tritium, <10(-15) for C-14, <10(-15) for Be-10 (down to <10(-16) in a later 3 h run), 2 x 10(-15) for Al-26, 2 x 10(-13) for I-129 and 9 x 10(-12) for Ca-41 and for Pu-239 (Pu-240) a 1.5 (0.5) pg per mg iron, which demonstrates the multi-element capability of the system. (C) 2015 Elsevier B.V. All rights reserved.