In 2007 the ANU received it’s NEC 250 KV single stage accelerator mass spectrometer (SSAMS), dedicated to radiocarbon measurement. In brief, targets are loaded into the ion source and sputtered with a +ve cesium ions. This liberates –ve ions that are accelerated toward the injector magnet. The low energy bending magnet (LEBM) bends the beam to 90 degrees to select the mass of interest and energisizes the ions to ~37,000 V.

Mission Control
High Energy Deck

One analogy is a car (Carbon 12), a truck (Carbon 13) and a semi-trailor (Carbon 14) on a race track, due to their differnt weights, or masses, they will handle the turn differently. But back to our carbon ions in racing stripes. After the injection magnet, an Einzel lens (EL) is placed before the acceleration tube, focussing the beam through the argon stripper without changing the energy of the beam. The stripper, or molecular dissociator, breaks up isobaric interferences, such as hydrides, but also removes electrons changing the ions polarity. The high energy bending magnet (HEBM) then bends the  +ve ions where we measure the carbon 12 and 13 currents in off-axis faraday cups. Carbon 14 continues down the beamline to be energy filtered at the electrostatic analyser (ESA) before the beam is directed into the silicon barrier detector. The stripper, high energy bending magnet (HEBM) and electrostatic analyser (ESA) are mounted on a high voltage insulated deck with a maximum of 250,000 V potential. This potential difference negates the need for the second acceleration used in tandem instruments. And yes, at those voltages it lives behind a cage.

Ion Source