Be-10 results from Trondheim 1 MV AMS

The 1 MV AMS system in Trondheim is regularly used for radiocarbon dating and provides stable measurement conditions for reliable results. The initial acceptance tests were conducted for 10Be, 26Al and 14C. However, for many years only 14C was measured. Recently the first tests with 10Be were done. We used BeO injection and a silicon nitride degrader foil for boron separation. The different charge states after accelerator and degrader foil were investigated to evaluate the performance. The 1+ charge state has by far the highest yield at an accelerator voltage of 1 MV. However, the low beam energy leads to low transmission through the degrader foil and also provides a poor peak separation of boron in the detector. Hence, we investigated the possibilities using the 2+ charge state. The higher ion energy in the degrader foil leads to a better transmission when using this charge state, compensating for the lower efficiency in the stripper. The separation of the boron beam after the ESA and in the detector was investigated to identify sources of background. A significant reduction of the blank ratio could be achieved by changing the used charge state. In order to test the routine performance of the system, several samples have been measured in the 2+-2+ configuration. This includes primary standards, which were used for normalization of the other samples. The precision for a single sample was 0.5 % at a nominal ratio of 10Be/Be 2.709·10-11. Secondary standards were used to prove the accuracy of the measurement. A detailed analysis of the performance as well as an outlook to real sample applications will be given.