Beta and gamma dose rate attenuation in rocks and sediment

Abstract This paper explores the attenuation of beta and gamma dose rate in a radioactive and in an adjacent inert layer for K, Th and U, individually, using Geant4 simulations. The simulated beta dose rate attenuation cannot perfectly be described by a single exponential function, thus the updated attenuation coefficients were obtained using two exponential functions with intercepts related to the different slopes. Attenuation coefficients and intercepts are provided in the manuscript. The newly obtained beta dose rate attenuation coefficients differ from the previously published values by a factor of 2, which results in a larger attenuation of the beta dose rate, so that the infinite matrix dose rate is reached at ~2 mm into the sediment and at ~1.5 mm into a rock. The new gamma dose rate attenuation coefficients are in good agreement with previously published literature and it is shown that the infinite gamma dose rate is reached at 300 mm in wet sediment with a density of 2 g cm−3.