The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of 26Al

Most accelerator mass spectrometry measurements of 26Al utilize the Al− ion despite lower source currents compared with AlO− since the stable isobar 26Mg does not form elemental negative ions. A gas-filled magnet allows sufficient suppression of 26Mg thus enabling the use of the more intense 26AlO− ion. However, most AMS systems do not include a gas-filled magnet. We therefore explored the feasibility of suppressing 26Mg by using a post-accelerator stripping foil. With this approach, combined with the use of alternative cathode matrices, we were able to suppress 26Mg by a factor of 20. This suppression was insufficient to enable the use of 26AlO−, however further refinement of our system may permit its use in the future.