For nearly 650 years, the fortress walls in the Chinese city of Xi’an have served as a formidable barrier around the central city. At 12 meters high and up to 18 meters thick, they are impervious to almost everything — except subatomic particles called muons.
Now, thanks to their penetrating abilities, muons may be key to ensuring that the walls that once protected the treasures of the first Ming Dynasty — and are now a national architectural treasure in their own right — stand for centuries more.
A refined detection method has provided the highest-resolution muon scans yet produced of any archaeological structure, researchers report in the Jan. 7 Journal of Applied Physics. The scans revealed interior density fluctuations as small as a meter across inside one section of the Xi’an ramparts. The fluctuations could be signs of dangerous flaws or “hidden structures archaeologically interesting for discovery and investigation,” says nuclear physicist Zhiyi Liu of Lanzhou University in China.
Muons are like electrons, only heavier. They rain down all over the planet, produced when charged particles called cosmic rays hit the atmosphere. Although muons can travel deep into earth and stone, they are scattered or absorbed depending on the material they encounter. Counting the ones that pass through makes them useful for studying volcano interiors, scanning pyramids for hidden chambers and even searching for contraband stashed in containers impervious to X-rays (SN: 4/22/22).
Though muons stream down continuously, their numbers are small enough that the researchers had to deploy six detectors for a week at a time to collect enough data for 3-D scans of the rampart.
2023-01-30 10:00:00
Original from www.sciencenews.org
An ancient Chinese wall has been a focus of archaeological study following the recent discovery of a muon scanning unveiling mysterious features situated within the historical landmark.
The wall, located in Shanxi province, dates back to the Ming Dynasty of the 15th century and is said to span almost 20 kilometers with a height of over five meters.
The muon scanning, a method used to scan layers within architecture without demolishing any structures, is a relatively new way of revealing the unknown particulars of ancient structures. Such finding could potentially uncover the secrets of a building without causing any physical damage to the site.
Muon scanning has recently started to be employed in applying physics and imaging in the world of archaeology. The technique was used in the exploration of the Chinese wall and the scan unveiled various unknown features, such as hidden niches, windows, and doorways which may have been concealed by the wall’s original builders for unknown purposes.
Though the features were found during the scans, there is little evidence to suggest what these features could be used for and researchers are yet to identify the reasons behind their creation. The mysteries and the existence of undisclosed structures may potentially hold information on the reasons of the wall’s construction and its purpose to past civilizations.
The use of advanced science has provided invaluable views and analyses of certain ancient structures which may have been missed or hidden in plain sight. In the case of the Chinese wall, the truth behind its hidden features may be uncovered soon with future research and development of the muon scanning technique.