A new approach for the detection of ¹⁰Be with AMS based on a silicon nitride foil stack

An improved AMS method has been developed at VERA for detecting the long-lived radioisotope ¹⁰Be and for separating it from its isobar ¹⁰B. Recently installed and projected AMS facilities mainly apply a degrader foil followed by an electrostatic or magnetic separator to remove ¹⁰B from the ion beam. This provides the highest suppression of ¹⁰B, but suffers from significant transmission losses of ¹⁰Be ions.
The new method achieves comparable ¹⁰B suppression with a passive absorber, consisting of a stack of Silicon nitride foils. Compared to a gas absorber, the smaller energy straggling in foils allows separation at lower energies. For a tandem accelerator operated at 3 MV, the charge state 2+ instead of 3+ can be used, with a stripping yield as high as 55%. This way, a high overall efficiency is gained. The setup is simple to operate, and provides good precision. We compare this new approach with other methods used at VERA and at other facilities. The foil stack setup was fully characterized with artificial samples from chemically and isotopically well-defined reagents, and is now routinely applied to real samples in various research projects. The new method is straightforward to be implemented, and was already adopted at another facility at higher terminal voltage [1], the use at a tandem with lower terminal voltage is explored in [2].
[1] S. Winkler et al., this conference.
[2] G. Scognamiglio et al., this conference.