10Be AMS measurements at low energies (E < 1 MeV)

The longlived isotope 10Be is of great importance in earth sciences for dating applications, reconstruction of the solar activity or in climate research. Routine AMS measurements with BeO samples are performed on accelerators with a terminal voltage above 2 MV. Applying the degrader foil technique for boron suppression, first tests with BeO samples on the 0.6 MV ETH/PSI machine were limited by background to a 10Be/9Be ratio of 10-13. The background was identified as 9Be which reaches the detector by scattering processes. By applying an additional magnetic mass filter to the high energy mass spectrometer the background was effectively removed. A 10Be/9Be background ratio of <5 x 10-15 was achieved. The overall efficiency (detected 10Be compared to BeO- injected into the accelerator) was 7-8%