Recent breakthroughs in muon technology are revolutionizing archaeology. This new technological advancement stands to revolutionize how researchers navigate and model subsurface environments. Muons are second generation elementary particles that are similar to electrons, except they are 207 times more massive. Due to their ability to penetrate the earth’s surface, they offer an unprecedented opportunity to explore concealed chambers and structures without destructive excavation. This pioneering method was recently put into practice at the City of David archaeological site in Jerusalem on an ancient wall.
Muons are produced when cosmic radiation interacts with Earth’s atmosphere. Plus, they’ve got a real short shelf life of just 2.2 microseconds. They shoot towards Earth at almost the speed of light just before they fall apart. Muons produce excellent imaging results. Muons lose energy very quickly when traveling through soil and rock. This helps some of them – particularly the most energetic ones – dive down to depths of over 100m.
The possible applications for muon technology in archaeology are extensive. By detecting changes in soil absorptivity to cosmic radiation particles, researchers can develop high resolution maps of subsurface structures. To detect these particles requires highly accurate measurements of both time and distance. As the radial distance from the source grows, lesser numbers of particles make it to the detector. Imaging can realistically be performed 30m away in a few hours and the imager can look directly at the target.
The Challenge of Discovering Underground Spaces
Archaeologists have been trying to perform this arduous task of lifting the veil from structures buried under ancient settlements for decades. As Prof. Oded Lipschits notes, “From the pyramids in Egypt, through the Maya cities in South America, to ancient sites in Israel, archaeologists struggle to discover underground spaces.” Although traditional excavation methods can be effective for above-ground structures, a complete survey of subterranean spaces still proves difficult.
“Above-ground structures are relatively easy to excavate, and there are various methods for identifying walls and structures below the surface,” Prof. Lipschits explained. “There are no effective methods for conducting comprehensive surveys of subterranean spaces beneath the rock on which the ancient site is situated.” This shortcoming in archaeological methodology has led to a ubiquitous search for new and better technologies.
In places, such as the Judean Foothills, the geological makeup only makes the situation more complex. “The top layer of hard limestone overlies soft chalk, in which the ancients easily carved out vast spaces for water reservoirs, agricultural uses, storage, or even dwellings,” said Prof. Lipschits. “Clearly, in such regions, most above-ground archaeological sites resemble Swiss cheese beneath the rock, but we have no way of knowing this.”
Reviving Muon Technology
Scientists have long employed muons in archaeological studies. Back in the 1960s, they used muons to look for undiscovered rooms inside Egypt’s pyramids. Breakthroughs in materials and design have brought this technology back and retooled it for today’s needs. “Our innovation lies in developing small and mobile detectors and learning how to operate them at archaeological sites,” stated Prof. Erez Etzion.
The present research introduces a unique approach for underground void detection through the application of cosmic radiation detectors. “If by chance we excavate above ground, reach the rock, and identify an entrance to a cavity, we could excavate it,” Prof. Lipschits added. “We have no way of locating the subterranean spaces in advance.” The researchers hope to remedy this to the public and policymakers with their new, more holistic approach.
“We ask physicists to respond to the archaeological need and develop smaller, simpler, cheaper, more durable, more accurate, and more power-efficient detectors,” Prof. Lipschits emphasized. In the next stage, we’re combining physics with AI. This integration will allow us to develop 3D images of subsurface structures using the large datasets known as particle showers produced by these detectors.
Future Prospects
The implications of this research are far-reaching, well beyond this initial study at the City of David. The team plans to test their methodology further at Tel Azekah in the heart of the Judean Foothills, overlooking the Elah Valley. By combining advancements in muon technology with AI capabilities, they hope to yield significant insights into ancient civilizations and their architectural practices.
The article’s publication is an important first step,” Prof. Lipschits stated. The researchers hope, with further focus and development, to improve their techniques and tools. They’re hoping this will open up new avenues for exploring archaeological sites that have otherwise stayed buried for thousands of years.
“The muon shower hits the ground at a fixed and known rate.” – Prof. Erez Etzion