11.10.2017

Knight helmets under the neutron beam

A funny woolly hat protects the helmet from scratches (Image: Silvia Zerbe/HZB).)

A funny woolly hat protects the helmet from scratches (Image: Silvia Zerbe/HZB).)

The helmet is clamped on a foam block. From the front, the neutron beam hits the helmet, the detector (grey) captures the neutrons and provides the image data (Image: Silvia Zerbe/HZB).

The helmet is clamped on a foam block. From the front, the neutron beam hits the helmet, the detector (grey) captures the neutrons and provides the image data (Image: Silvia Zerbe/HZB).

Detectives with neutrons: Alan Williams, Nicolay Kardjilov, Francesco Grazzi, and David Edge (Image: Silvia Zerbe/HZB).

Detectives with neutrons: Alan Williams, Nicolay Kardjilov, Francesco Grazzi, and David Edge (Image: Silvia Zerbe/HZB).

It happens quite often that Nikolay Kardjilov has interesting guests. The HZB expert on neutron tomography is in demand worldwide, even when it comes to investigating valuable cultural treasures.

Just recently, four knight helmets were waiting for their analysis. "The woolen caps should protect the valuable original piece from scratches" explains David Edge, the curator of the Wallace Collection in London.

In addition to paintings and furniture from last centuries, the Wallace Collection hosts one of the most important collection of armor and weapons from Europe. The four knight helmets were dated from the 15th century, presumably made in Italy, Edge reports.

He and his colleague, the archaeometallurgy expert Alan Williams, have transported the helmets from London to Berlin-Wannsee in their hand luggage. At the Berlin neutron source BER II, Nikolay Kardjilov helps in the investigation of the helmets.

Through the centuries the surface of the helmets has changed by constant polishing. As a result, the engraved stampings are no longer visible. However, these prehistoric stampings point to the workshop where the helmets were once forged. But even if they are polished
superficially, condensation in the microstructure of the metal is still detectable.

With neutron-tomography these condensations can be made visible. "We have the opportunity to use the so-called phase contrast, so we can work out the traces clearly," explains Nikolay Kardjilov.

The metal specialist Alan Williams added: "We are working like forensic experts, but much more cautiously. Neutron tomography, however, is a non-destructive method, we see the stamping and do not damage the helmets at all."