Cosmogenic in situ production of radionuclides: Exposure ages and erosion rates

Experimental data for the cosmogenic in situ production of radionuclides and its depth dependence are used for two applications, the determination of exposure ages and of erosion rates. Concentrations of the long-lived radionuclides ¹⁰Be, ¹⁴C and ²⁶Al in quartz are presented as function of exposure age, depth before exposure and erosion rate after exposure. It is shown that the cosmogenic production before exposure can introduce important corrections to the representation without consideration of pre-exposure production. Depth profiles of ¹⁰Be, ¹⁴C and ²⁶Al in quartz and sulfur, of ³⁶Cl in K₂O, CaCO₃, granite and concrete and of ⁵³Mn in Fe₂O₃ are given as function of erosion rate. Consequences to determinations of neutron fluences in Hiroshima are discussed.