ABSTRACT

For the purpose of estimating the degree of evaporation loss of cosmogenic nuclides in the ablation products of materials by atmospheric heatings, a few laboratory ablation experiments were performed. Small Fe and Ni metal chips in which radioactive ⁵⁴Mn, ⁵¹Cr and ⁵⁸Co were induced by fast neutron irradiation, were heated to 10–20°C above the melting point under 40mtorr air pressure. Gamma ray activities of the radionuclides measured before and after the heating show that ⁵⁴Mn evaporates much faster than Fe, ⁵¹Cr and ⁵⁸Co evaporate much slower than ⁵⁴Mn, but faster than the major elements, Fe and Ni.