The Mystery of the Lead Coffin
Munich neutron researchers study mummy
Tense expectation at the arrival of an archaeological sensation. Carefully packed in this crate is a 2m long coffin, roughly 1,700 years old, found in excavations near Rome. Who is inside, nobody yet knows, for the coffin has not yet been opened. At the TU (Technische Universität) in Munich, the mysterious find is to be examined. He will lead the examination. Burkhard Schillinger is a “neutron scientist” and has been preparing for weeks. He wants to bombard the coffin with neutrons, so to produce an image of the coffin`s contents, without opening it. (Schillinger) “We are very eager to find out if we will be able to see anything, for we ourselves do not yet know if it will work. We are at the limit of what is physically feasible with this analysis, and we are very excited.”
Can the Bavarian researchers solve the mystery of the Roman lead coffin? In this tomograph, the first measurements will be undertaken. The crate is handled like a “raw egg”, for any kind of shaking could damage the contents. To ensure that everything goes according to plan, the archaeologist Anna Gallone has traveled especially from Italy. She, along with an international team, discovered the coffin. And this is what it looks like. It weighs about 350kg, and has a distinct form. The coffin comprises thick walls of lead that were folded together over the corpse. An extremely lavish procedure for this period. (Anna) “It was definitely someone that was very rich because of the quantity of lead that was used for the coffin. The way in which was produced was very expensive. It must have been someone of high status, but exactly what position the person is hard to tell at this stage.”
The only certainty is that the person was buried here, in the historical town of Gabii, 18km east of Rome, today an excavated field. Archaeologists have found more than 20 graves here. Anna Gallone (The Gabii Project's field director) has also investigated some of them, but the lead coffin is the only one of its kind. The graves were situated on a tufo-plateau, and were subject to rain and sun for centuries. Amazingly, despite these adverse conditions, the bones have survived well. From them, the archaeologists can roughly establish the age of the coffin - the 3rd century AD. But who could afford such a burial? Back in Munich. Burkhard Schillinger prepares the main test. For this, one of the most advanced neutron sources in Europe is available. To get a good picture, the coffin must be placed directly in front of the source. Because neutrons possess no charge, like miniscule probes, they can be used to research the quality of metals without disturbing them, a method so good for the analysis of the coffin, it is as if it was designed for it. But there is a problem, for there are several points where the coffin is not sealed, and through these holes earth has found its way inside. Could this disturb the analysis? (Schillinger) “Earth, especially when it is wet, is an enormous obstacle for the neutrons. The lead that you see here is easy for us to get through, but since neutrons are sensitive to light elements, then they are naturally also sensitive to soil, and we have grave doubts whether it will work.”
It starts! During the analysis the scientists have to leave the room due to the strong radiation. What happens now behind these steel doors can be imagined in this way: the neutrons penetrate the interior of the coffin. Some will be diverted, or absorbed. The rest will pass through the coffin and hit a luminous screen covered with a layer of lithium. The lithium atoms burst and light up the screen. A sensitive camera records the light and saves it as a photo. But in practise it does not always work. Also this time. On the monitor, the first image appears. As feared, the soil diverted the neutrons too strongly. The layer of lead can been seen clearly, but beneath everything is black. Burkhard Schillinger and the archaeologists start once again, this time with stronger neutrons. They are specifically interested in recognisable grave goods, clues to the status of the person. And really, the image on the screen allows the recognition of the first details. (Anna) “There is actually the possibility that what we are looking at is the skeleton. What I find particularly noteworthy is this area. This here is possibly the pelvis. And beneath, this long shape, might actually be the backbone.” Grave goods, by the way, are not recognisable. To find out more, the coffin will be opened in the next few weeks at Rome. Until then, the archaeologists can only speculate. (Anna) “Well I mean the problem of interpreting this coffin, is that there is no comparable find in Italy or the Roman Empire. For this reason it is possible that person was a foreigner, from northern Europe or from the eastern provinces.” The neutron analysis was able to deliver the first clues. The coffin contains human remains. These will have to be examined in greater detail at Rome.
Translated from the German by Jamie Sewell
13 November 2010
The abstract of Terrenato's talk is here.
