Prof Keith Fifield visits AMS group

The Accelerator Mass Spectrometry group recently hosted one of the pioneers of AMS, Prof Keith Fifield of the Australian National University.

The AMS detects rare cosmogenic isotopes 14C, 10Be and 26Al at abundances in the order of one atom in 1016. The 14C laboratory has made exceptional progress and Prof Fifield’s visit coincided with the measurement of the 1000th AMS 14C sample. Detection precision is <0.5%, which is in line with international levels, and accuracy has been demonstrated by measuring inter-laboratory comparison samples.

The AMS team is currently working on reducing background contamination and reducing sample graphitization time. Instrument blanks on the AMS are the equivalent of 70 000 years, suggesting that the iThemba LABS AMS radiocarbon facility is going to be comparable with the best in the world. The AMS group secured IAEA funding to procure instrumentation to measure 13C/12C ratios necessary in the production of radiocarbon dates. The capability to prepare and measure 10Be and 26Al is awaiting the completion of lengthy procurement procedures.

The team is also co-supervising a PhD and 9 MSc candidates, hosting students and interns from several institutions, and participating in research partnerships with local and international partners. The in-house research is currently focusing on 236U tracing in the ocean, climate reconstructions, and dating the climate record from the Tswaing meteorite impact crater near Pretoria.