The first four years of the AMS-facility DREAMS: Status and developments for more accurate radionuclide data

Abstract DREAMS, the DREsden AMS-facility, is performing routine accelerator mass spectrometry of 10 Be, 26 Al, 36 Cl, 41 Ca, and 129 I for a wide range of applications. All DREAMS-data is normalised directly to primary standards or traceable to those via cross-calibration of secondary standards. Recent technical developments such as a low-memory ion source for 36 Cl and 129 I and sophisticated tuning strategies for 129 I led to improved-accuracy data. Tests of ion source output have been performed with different metal binders, sample-to-binder mixing ratios, and compaction pressures in order to find optimal parameters. The highest and most stable outputs have been obtained for 10 Be, 26 Al, and 41 Ca for the following binders and mixing ratios (by weight): BeO:Nb, 1:4; Al 2 O 3 :Ag, 1:1; CaF 2 :Ag, 1:4. Higher beam currents generally result in reduced statistical uncertainty. Cross-contamination and long-term memory seem to be underestimated problems asking for further tests and improvements such as the development of low-level in-house-standards.