A gas-multiplication telescope detector for low-energy ions

A new detector has been designed and built for the accelerator mass spectrometry (AMS) system at the MIT BEAMS Laboratory. This gas ionization detector uses the common segmented-anode design to measure energy loss in two sectors. It differs from existing designs in having wire grid anodes rather than flat plates in order to permit gas multiplication of the signals induced by drift electrons from initial ionization of the gas. The detector output for 2.5 MeV ions is easily sufficient to feed conventional pre-amplifiers and is without interfering levels of electronic noise. Initial testing indicates that this detector resolves 14C2+ from all other well-defined signal clusters in the Er vs. ΔE spectrum at the level required for operation of the AMS instrument.