Highly sensitive AMS measurements of 53Mn

Abstract Our AMS system, with the gas-filled detector system GAMS, has been optimized for measurements with 53 Mn. A high sensitivity has been achieved. A newly installed cesium sputter ion source yields an improved emittance, and thus a higher mass resolution. By the extraction of the manganese molecule MnF − instead of MnO − we can suppress the isobaric chromium background in the ion source by more than a factor of three. The GAMS system achieves an isobaric suppression factor of about 3 × 10 8 . Measurements on blank samples yielded upper limits for the 53 Mn/ 55 Mn ratios of 7 × 10 −15 .