The dissociation of 13CH and 12CH2 molecules in He and N2 at beam energies of 80–250keV and possible implications for radiocarbon mass spectrometry

AixMICADAS, the accelerator mass spectrometer dedicated to 14C recently installed in Aix-en-Provence, France

“…In operating conditions, the overall transmission, including losses from ion optics and conversion from 1 À to 1 + , is about 47% for carbon ions with energies of about 240 keV [20]. After the double-stage acceleration, ion beams are filtered by the high-energy 90°magnet and by a 90°electro-static analyzer before entering through a silicon nitride window into the final detector.…”

“…It is the first prototype outside the ETH that operates with a helium stripper for improved ion transmission [20] and includes a hybrid ion source to allow work involving graphite targets and CO 2 gas. The ion source is supplied by a versatile gas interface [28] from three different sources: a cracker for CO 2 in glass ampoules, an elemental analyzer for combusting organic matter and an automated system to handle carbonates using wet chemistry.…”

Mass spectrometric detection of radiocarbon for dating applications

“…Recently, we have measured dissociation cross-sections for mass 14 molecules in N 2 and helium in the energy range of 80-250 keV [9]. Whereas in N 2 cross sections go down at ion energies of %100 keV, the He data remain fairly constant.…”

Status of mass spectrometric radiocarbon detection at ETHZ

“…The ion energy for the stripping process is exclusively provided by the acceleration at the ion source and is about 45 keV. Helium is used as stripper gas, as it has shown a high yield for the 1 + charge state at low energies [5] as well as constant cross sections for molecular destruction over a large energy range [6]. The spectrometer following the gas stripper comprises an electrostatic analyzer (ESA), followed by a magnetic sector field analyzer.…”