Search for Supernova-ProducedFe60in a Marine Sediment

An ${}^{60}\mathrm{Fe}$ peak in a deep-sea FeMn crust has been interpreted as due to the signature left by the ejecta of a supernova explosion close to the solar system $2.8\pm 0.4\mathrm{Myr}$ ago [Knie et al., Phys. Rev. Lett. 93, 171103 (2004)]. In an attempt to confirm this interpretation with better time resolution and obtain a more direct flux estimate, we measured ${}^{60}\mathrm{Fe}$ concentrations along a dated marine sediment. We find no ${}^{60}\mathrm{Fe}$ peak at the expected level from 1.7 to 3.2 Myr ago. Possible causes for the discrepancy are discussed.