Operating the 120° Dipol-Magnet at the CologneAMS in a gas-filled mode

Routine measurements of the last years at the 6 MV AMS system showed a good isobar suppression for all light isotopes, measured with the Degrader-Foil-Method, especially 36Cl and 10Be. However, the efficiency is reduced due to the charge state distribution generated by the degrader-foil. For measurements injecting atomic 26Al, the ionization efficiency becomes the bottleneck, which leads to a relatively low ion source output. In the case of AlO−, the output is expected about one order of magnitude higher. However, to use AlO− the isobar interference of 26Mg will become an issue. It has to be suppressed in several steps, e.g. by different dE/dx methods like TOF, degrader-foil or gas-filled magnet.