Cosmic-Ray Muons Used to Detect Underground Tombs In Naples - Slashdot

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Slashdot reader Bruce66423 shared this report from LiveScience: Cosmic rays and lasers have revealed that deep underneath the city streets of Naples, Italy, lie the remains of the Greeks who originally settled the area, as well as the catacombs of Christians who lived there during the Roman era nearly two millennia ago, a new study finds...

The layers of contemporary buildings make it difficult to access ancient sewers, cisterns and tombs 33 feet (10 meters) underneath the streets, so a group of Italian and Japanese researchers hypothesized that they could identify previously unknown burial hypogea from the Hellenistic period using 21st-century techniques. Their study, published April 3 in the journal Scientific Reports, details how they used muography to detect underground voids that were unknown to archaeologists... In 1936, scientists discovered that muons are produced by cosmic rays in Earth's atmosphere, and that these tiny particles can easily penetrate walls and rocks, scattering in open spaces. In this study, the muons' tracks were recorded using nuclear emulsion technology, in which extremely sensitive photographic film is used to capture and visualize the paths of the charged particles.

By measuring muon flux — how many muons arrive in a particular area over time — and direction using a particle detector, researchers can peer into volcanoes, underground cavities and even the Egyptian pyramids through muography... Valeri Tioukov, a physicist at Italy's National Institute for Nuclear Physics, and his colleagues placed the muon tracking devices 59 feet (18 m) underground, in a 19th-century cellar that was used for aging ham, where they recorded the muon flux for 28 days, capturing about 10 million muons... 3D laser scans of the accessible structures can then be compared with the measured muon flux. Anomalies in the muon flux images that are not visible in the 3D model can be confidently assumed to be hidden or unknown cavities.

Muography revealed an excess of muons in the data that can be explained only by the presence of a new burial chamber. The chamber's area measures roughly 6.5 by 11.5 feet (2 by 3.5 m), according to the study, and its rectangular shape indicates it is human-made rather than natural.