Accelerator mass spectrometry (AMS) for beryllium-7 measurements in smallest rainwater samples

Beryllium-7, mainly measured via γ-spectrometry, is used as a (natural) radiotracer for education and science. For activities < 0.1 Bq and samples containing also longer-lived 10 Be, accelerator mass spectrometry (AMS) is the method-of-choice. We demonstrate that 7 Be and 10 Be can be quantified at the Dresden AMS facility on the same prepared BeO. Detection limits ( 7 Be) are ~ 0.6 mBq. Samples as small as tens of millilitres of rainwater can be chemically processed (after acidification) within a few hours without expensive and slow ion exchange. Isobar ( 7 Li) suppression by chemistry and AMS is sufficient to guarantee for an ultrasensitive, cheap, and fast detection method for 7 Be allowing high sample throughput.