Highly sensitive ²⁶Al measurements assisted by ILIAMS

The higher ion source output from Al2O3 for AlO− compared to Al− can improve the sensitivity of 26Al AMS measurements. One obstacle is the more complicated isobar suppression after AlO− extraction: For the metallic Al anion the 26Mg background is suppressed in the ion scource. With ion-laser interaction mass spectrometry (ILIAMS), however, the 26Mg isobar can also be completely suppressed for extracted AlO− ions. This now allows the use of the more prolific AlO− beam at facilities with terminal voltages <10 MV.
At the 3MV Vienna Environmental Research Accelerator (VERA) routine ILIAMS assisted AMS measurements of 26Al are performed utilizing AlO− and charge states 2+ and 3+ on the high-energy (HE) side of the spectrometer. Tests of Al2O3 mixtures with different metals were conducted to achieve the optimal generation of AlO− currents.
Admixtures of Cu or Ag powder showed good results but were surpassed by mixing Al2O3 with Fe powder. In addition, results of first experiments will be presented regarding the utilization of ILIAMS assisted 26Al measurements with lower terminal voltages and using the 1+ charge state on the HE side.