OSL dating.

The uncertainty associated with the luminescence age (test year, 2019) is given at the 68% level of confidence, calculated following a procedure of error propagation [41]. The luminescence age corresponds to the quotient of the paleodose, P, and the dose rate, Dr; those shown were rounded to the nearest 5 years. The two ages calculated for sample 438–2 take account of different histories of use of the brick following manufacture (A and B), as discussed in the main text. The overdispersion in P, σB, is an indicator of beta dose rate heterogeneity in the case of heated samples, and the number of determinations (aliquots), n, is given in the adjacent column. In calculating the annual dose rate, Dr, the beta dose rate Dβ includes a small contribution (0.035 mGy/a) from radiation emitted by lithogenic radionuclides within the quartz grains. The average moisture content of ceramic and environmental materials was assumed to be 3±1% for sample 348–2 and 10±2% for sample 348–5, by weight.