Distribution of natural beta dose to individual grains in sediments

In luminescence dating using single grains of quartz, statistical protocols are used to compute the most appropriate dose from the distribution of palaeodoses. The distribution of palaeodoses arises due to, (1) heterogeneity (at grain level) in bleaching at the time of deposition, (2) heterogeneous distribution of beta emitters present as randomly distributed feldspars (Mayya et al. in Radiat Meas 41:1032–1039, 2006) and, (3) heterogeneous distribution of grainsizes (Guérin et al. in Radiat Meas 47:778–785, 2015). Mayya et al. (Radiat Meas 41:1032–1039, 2006) demonstrated that random distribution of feldspar grains(with up to 14% stoichiometric K) and shorter range of beta particles (~ 2.3 mm in quartz) lead to significant variation in dose received by individual grains of quartz. This study improves upon Mayya et al. (Radiat Meas 41:1032–1039, 2006) by, (1) using a more realistic energy deposition function that was estimated using Monte Carlo simulations and (2) computing the effects of porosity of the sediment and beta straggling on the dose distribution function. It additionally concludes that effects of beta straggling are small and can be ignored. Ages based on new calculations led to improved concordance with control ages.