Manganese-53: Development of the AMS technique for exposure-age dating applications

The cosmogenic isotope 53Mn is produced by spallation of iron in surface rocks. The long half life of this isotope makes it attractive for use in erosion rate studies in slowly eroding landscapes such as Australia. We describe the development of AMS methods for detection of 53Mn using the 14UD accelerator at the Australian National University. The first step of this development involved the production of 53Mn using a heavy-ion fusion–evaporation reaction to make test standards. Then, the chemistry protocol for isolating 53Mn and reducing the Cr levels, of which 53Cr is a serious interfering isobar, was developed. Lastly we employed a gas-filled magnet which was used to discriminate 53Mn from the intense 53Cr background.