Underwater dosimetry of EP1 Epagnette shipwreck (Somme, France), - Archive ouverte HAL
Communication Dans Un Congrès Année : 2017

Underwater dosimetry of EP1 Epagnette shipwreck (Somme, France),

Résumé

The EPA1 Epagnette wreck and its cargo of clay roofing tiles were discovered in 2002 during a survey in the Somme river near the village of Epagnette (Epagne-Epagnette, Somme France). It is a rare example of river navigation in the region. The only other example, the EPA1 Canche wreck, is a sea and river coaster found in the Canche river (Beutin, Somme, France). As part of an interdisciplinary research program on medieval and modern sea-river shipping, under the supervision of Eric Rieth (LAMOP-CNRS, National Navy Museum), excavations were undertaken since 2011. After a site evaluation campaign in 2011, a first multi-annual excavation program took place between 2012 and 2014, followed by a second one between 2015 and 2017 We have been involved in this project from the beginning to date the tiles from the cargo, in parallel with the tree-ring research on the wreck and the typo-chronological analysis of the tiles. Our measurements were first on lots of flat and curved tiles, then on a lot of curved and trapezoid-shaped tiles. All these tiles coming from outside of the wreck so as not to disrupt the cargo still in place. Our study shows that the tiles are dated from the 17th and early 18th centuries (flat tiles, 17th century ; curved tiles, 3rd quarter of 17th c. ; trapezoid-shaped tiles, 2nd half of the 17th c.). This result diverges from that obtained by dendrochronology which dates the felling of the trees of 1746/1747[1]. The analysis of the tiles shows that these are newly produced specimens and that they do not come from any re-use. Storage for decades does not appear to be historically evidenced (from the accounts of tile-makers, in particular). It raises the question of the tiles dating. If the assessment of the archaeological dose is not a problem per se, it is not the same for the annual dose. The aim was to assess the dose-rate at the river bottom. This was done on the basis of rough estimates of the radioactivity of river bed sediment and water. In order to have a better estimate, we implemented two approaches for the 2016 campaign: 1) Sampling tiles inside the cargo to reduce the error on the annual dose by increasing the dose-rate contribution from the tiles, homogeneous with regards to the radioactivity. 2) measuring in-situ dosimetry using small dosimeters containing Al2O3-C pellets. These were install within the cargo during the 2016 campaign and will be raised one year later, during the 2017 campaign. Meanwhile, various models of the tiles environment were built to simulate, using DosiVox software [2], the dose-rate absorbed by the tiles. The results of this new measurements campaign will be presented and their implications on the dosimetry of underwater sites discussed. References 1.Lavier C., 2015, Dendrocrhonologie, in E.Rieth ed. Epave EP1-Epagnette (Somme), Rapport final d'operation, unpublished report, SRA Haut-de-France 2.Martin L, Incerti S, Mercier N., 2015. DosiVox: Implementing Geant 4-based software for dosimetry simulations relevant to luminescence and ESR dating techniques. Ancient TL. 33(1), 1-10.
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Dates et versions

hal-03152289 , version 1 (08-06-2022)

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  • HAL Id : hal-03152289 , version 1

Citer

Antoine Zink, Elisa Porto. Underwater dosimetry of EP1 Epagnette shipwreck (Somme, France),. 15th International Conference on Luminescence and Electron Spin Resonance Dating 11-15 septembre 2017, Sep 2017, Le Cap, South Africa. ⟨hal-03152289⟩

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