Attenuation of beta radiation in granular matrices: implications for trapped-charge dating

Abstract. Mineral grains within sediment or rock absorb a radiation dose from the decay of radionuclides in host matrix. For beta component, estimated rate must be adjusted for attenuation particles mineral grains. Standard calculations, originally designed thermoluminescence dating pottery, assume that grain is embedded homogenous medium. However, most current applications trapped-charge concern sand- silt-sized dosimeters granular sediment. In such cases, radionuclide sources are not homogeneous but localised discrete held on surfaces. We show here mean to dosimeter matrix dependent grain-size distributions source and bulk sediment, addition size dosimeters. further argue U Th likely primarily surfaces, which causes significantly higher than distributed uniformly throughout typical well-sorted medium sand, rates derived surface by ∼ 20 % 30 %, respectively, compared distribution sources. account these effects using an expanded model – including effect moisture validate against Monte Carlo transport simulations geometry packed spheres.