Radiocarbon AMS towards its low-energy limits

A design for a novel tabletop AMS system is presented. The mini radiocarbon dating system (MICADAS) is based on an acceleration unit that uses vacuum to insulate the high-voltage terminal. The acceleration voltage (200 kV) is supplied by a commercially available power supply. A gas stripper is used to charge exchange the negative ions extracted from the ion source into charge state 1(+) and to break up the interfering molecules of mass 14 amu in multiple collisions. Cross-sections of these molecular break up processes in the energy range 220-590 keV are presented. The primary component of the new instrument, the acceleration unit, is now operational. Test measurements of the unit in combination with the mass spectrometers of the compact POI/ETH Pelletron based AMS system have been successfully made. First results demonstrate the capability of radiocarbon dating at 200 kV terminal voltage. (C) 2004 Elsevier B.V. All rights reserved.