Setting-up an accelerator mass spectrometry (AMS) facility: The role of chemistry

Medium-energy AMS facilities such as the 5 MV British SUERC and French ASTER or the two 6 MV German DREAMS at Dresden[1] and Cologne AMS have recently been installed. These machines need physicists to get them running but also scientists to establish AMS chemistry on-site. As it is not advisable to change simultaneously two ”things”, i.e. machine and chemistry, a cooperation with the teams of ASTER and VERA helped to check the new sample preparation of DREAMS. A ”good” AMS sample has two features: high stable isotope current and low isobar concentration. High chemical yields and low concentrations of other elements, from the matrix or chemical products used, are less important, but may play a role if e.g. a matrix contains Ti being introduced into BeO-targets as shown by µ-XRF [2] and recent µ-PIXE analyses of final AMS-targets at HZDR. A processing blank with low radionuclide/stable nuclide ratio is essential for projects near the detection limit. Finally, a fast, easy and cheap separation guarantees high sample throughput and reasonable costs. Ref.: [1] www.dresden-ams.de. [2] S. Merchel et al., NIMB 266 (2008) 4921. Ackn.: Thanks to T. Schildgen, C. Yildirim (Potsdam), K. Klemm, M. Fuchs (TUBA), M. Arnold, G. Aumaître (ASTER), A. Wallner (VERA).