Physics-based techniques are playing an increasingly important role in the analysis of archaeological artefacts. At the 34th Symposium of Archaeometry in Zaragosa, Spain, this week Manolis Pantos and colleagues at the Daresbury and Rutherford Appleton Laboratories in the UK will describe how they used beams of synchrotron radiation and neutrons to examine a bronze helmet from ancient Greece. The non-destructive techniques employed by the group have helped to unravel the object’s unusual history and could now used to investigate other ancient artefacts.
Pantos and co-workers analysed a “Corinthian-type” battle helmet that dates from the 7th century BC and is currently being exhibited at Manchester Museum. Alistair Jackson, an art historian at the museum, suggested that the helmet was made by beating out a single lump of bronze — a technique that was so efficient that it was still being used in Italy in the 15th century — but he also suspected that the nose-guard of the helmet might date from much later.
To investigate this, Pantos and co-workers subjected the helmet to a variety of techniques — surface X-ray diffraction, X-ray fluorescence and infrared spectroscopy — using the Synchrotron Radiation Source (SRS) at Daresbury. They also used the ISIS neutron source at Rutherford to determine the microstructure of different parts of the object. Neutrons are able to probe the bulk of the object, as well as the surface.
“We have confirmed Alistair Jackson’s suspicions that the nose-guard is indeed a modern prosthesis,” Pantos told PhysicsWeb. According to the team, the nose-guard dates from the 19th century and was probably added by the person who found the helmet. It is made from a copper-zinc alloy (brass) while the helmet itself is made of copper and tin (bronze).
Moreover, information about the orientation of crystallites in the bronze provided by neutron texture analysis supports Jackson’s theory that the helmet had been hammered out from a single piece of alloy.
“We believe that this high-profile case will now encourage other investigators and museum curators to use our approach,” said Pantos. “We have the potential at SRS and ISIS to probe whole statues, whether made of bronze or even marble.”
