Campo del Cielo iron meteorite: Sample shielding and meteoroid's preatmospheric size

Abstract— Long‐lived cosmogenic radioisotopes, ¹⁰Be, ²⁶Al, ³⁶Cl, ⁴¹Ca and ⁵⁹Ni, have been measured in five samples from the Campo del Cielo iron meteorite by accelerator mass spectrometry (AMS). The ³⁶Cl activities were significantly above the background. For the concentrations of the other four radioisotopes, only upper limits were obtained that were, however, consistent with the ³⁶Cl result. The measured ³⁶Cl activity allowed an estimate of the meteoroid's preatmospheric size: a radius larger than 300 cm and a mass of at least 840 000 kg. We conclude that this meteorite might be one of the largest meteorites to have been recovered.