Analyse par activation neutronique avec des neutrons rapides de cyclotron de monnaies en bronze à forte teneur en plomb : résolution du problème lié à l'auto absorption.

摘要

Analysis of Marseille bronze using the fast neutron activation using a cyclotron show that the lead content could vary from 1 5 % to 24 % within a same monetary series. The aim of this study is to check if these variations are due to a voluntary change in the alloy component or to a natural lead segregation on the mould during the casting process. To cast double sesterces bronze blanks, we have recreated a limestone mould. This mould was made in the same way that the one recovered at the gallo-roman site of Châteaubleau (IIIe c. A.D.). Due to the high lead content of the blank and to their thickness (6 mm), self absorption of gamma ray on the alloy prevents precise determination of lead content. In order to correct self absorption we build a model based on calculation of a corrective factor. This model is applied to the study the blank cast with a modern industrial bronze alloy.