Dating by the method of thermoluminescence of a prehistoric campfire found in the archaeological site of Baixa do Umbuzeiro, RN, Brazil

In this work it was carried out the dating of a prehistoric campfire found in the archaeological site of Baixa do Umbuzeiro - RN, by the method of thermoluminescence (TL). To perform the dating, were collected five sediment samples from different parts of the campfire. The accumulated dose in these samples was obtained by the method of regenerative doses in which the natural TL intensity is compared with the TL intensity of doses supplied in artificial laboratory through a Co-60 source. The determination of the annual dose rate was performed by the determination of the levels of U, Th and K in the samples by gamma spectrometry with germanium hyper pure detector (GeHP). The five values found for accumulated dose were evaluated by the statistical test ANOVA, having been discarded one of these. The accumulated dose average is 12.5 ± 1.5 Gy and the annual dose rate is 3.31 ± 0.60 mGy/year. These values provided an age of about 3776 ± 821 years for the campfire of Baixa do Umbuzeiro. (author)