A team of archaeologists have used muography to reveal a hidden chamber in the necropolis of Neapolis in Naples, Italy.
Neapolis was a Greek city founded during the 3rd century BC, whose remains are located around 10 metres beneath the current street level in the Sanità neighbourhood of present-day Naples.
The city emerged as an important trading centre in Magna Graecia and the Mediterranean, but would eventually be absorbed into the expanding Roman Republic around 327 BC.
The study was conducted by the University of Naples Federico II and the National Institute of Nuclear Physics (INFN), in collaboration with the University of Nagoya (Japan).
The team applied muography, a technique that uses cosmic ray muons to generate three-dimensional images of volumes using information contained in the Coulomb scattering of the muons.
Since muons are much more deeply penetrating than X-rays, muon tomography can be used to image through much thicker material than x-ray based tomography such as CT scanning.
Several detectors capable of detecting muons were placed underground in the highly populated “Sanità” district at a depth of 18 metres to measure the muon flux over several weeks.
Measurements of the differential flux in a wide angular range have enabled the researchers to produce a radiographic image of the upper layers that has revealed known and unknown structures beneath the ground surface.
One of the most interesting structures is an inaccessible hidden chamber from the Hellenistic period, which according to the researchers likely contains a burial.
“From the number of muons that arrive at the detector from different directions, it is possible to estimate the density of the material they have passed through,” said lead author Valeri Tioukov, a researcher at the INFN of Naples. “We found an excess in the data that can only be explained by the presence of a new burial chamber.”
Header Image Credit : Tioukov, V., Morishima, K., Leggieri, C. et al