Speaker
Description
The presence of long-lived radionuclides provides insights into the solar system's history. The radionuclide $^{60}$Fe (t$_{1/2}\,$=$\,$2.6$\,$Myr) is mainly synthesized in massive stars and subsequently ejected by supernovae. Embedded into dust grains, $^{60}$Fe can enter the solar system and be deposited into terrestrial archives, where it evidences stellar explosions even after several million years.
Expanding upon the discovery of increased levels of $^{60}$Fe in million year old deep-ocean material and a recent influx into Antarctic snow, we now aim to investigate the influx pattern in the unexplored time interval 50$\,-\,$80$\,$kyr before present. A 300$\,$kg sample of the Antarctic EPICA Dronning Maud Land (EDML) ice core was selected to probe the recent $^{60}$Fe influx and implications for the formation of the Local Interstellar Cloud. Benefiting from their remoteness, Antarctic ice cores offer a unique geological archive with minimal terrestrial contamination.
The ultra-low deposition of a few $^{60}$Fe atoms per cm$^{2}$ per year can only be investigated by accelerator mass spectrometry. The DREAMS facility (HZDR) was used to measure the cosmogenic radionuclides $^{10}$Be, $^{26}$Al and $^{41}$Ca, whereas HIAF (ANU), as the sole capable facility worldwide, is required for measurements of $^{53}$Mn and $^{60}$Fe. We report on the recent results of this project.
