On the use of the infinite matrix assumption and associated concepts: A critical review

The infinite matrix assumption is commonly used to derive dose rates in the field of paleodosimetric dating methods. The update of nuclear data allowed calculating new dose rate conversion factors and attenuation factors for taking account of grain size. The relevance of the infinite matrix assumption was found to be limited to specific cases and a discussion of potential errors in estimating dose rates to natural dosimeters in sedimentary media is proposed. A new set of geometric features is shown to be of paramount importance for estimating dose rates in sedimentary media. To quantify these effects, Monte Carlo modelling was applied and the architecture of the programmes is described. It is also shown that proper characterization of sediment samples, coupled to the modelling of radioactivity in these sediments may provide more accurate dose rates to quartz grains, down to the single grain scale.

► Updated dose rate conversion factors and attenuation factors are proposed.
► The infinite matrix assumption has a limited range of validity.
►  A new set of geometric features is of paramount importance for estimating dose rates.
► Monte Carlo simulations provide more accurate dose rates than classical approaches.
► Single grain dose rate distributions are obtained using Geant4.