New data for cosmogenic ⁵³Mn and ⁶⁰Fe in iron meteorites

Cosmogenic nuclides in meteorites can provide information on cosmic ray exposure (CRE) histories. In space, meteoroids are irradiated by galactic cosmic ray particles, inducing the production of cosmogenic nuclides (¹⁰Be, ²⁶Al, ³⁶Cl, ⁴¹Ca, ⁵³Mn, ⁶⁰Fe). Meteorites are routinely measured for ¹⁰Be, ²⁶Al, and ³⁶Cl. However the database for ⁵³Mn and ⁶⁰Fe is scarce due to the low availability of high-MV accelerators and the debate over the half-lives of ⁵³Mn and ⁶⁰Fe. We Report new ⁵³Mn and ⁶⁰Fe data for iron meteorites measured at Canberra (⁵³Mn, ⁶⁰Fe) and Munich (⁶⁰Fe). Among these radionuclides, ⁵³Mn has the longest half-life, thus is least influenced by terrestrial ages. The advantage of ⁵³Mn and ⁶⁰Fe isotopes is that only two (Fe, Ni) and one (Fe) target element(s), respectively, dominate production, overcoming the problem of inhomogeneous S and P distribution. Our new ⁶⁰Fe data almost doubles that present in the literature. We measured ⁵³Mn in seven subsamples of the iron meteorite Twannberg. The new ⁵³Mn and ⁶⁰Fe data, with ¹⁰Be, ²⁶Al, ³⁶Cl, ⁴¹Ca and the noble gases, will better constrain the CRE histories of meteorites and will also serve as benchmarks to validate and improve Monte-Carlo model calculations.