According to a new study, researchers are investigating the fortress wall of Xi’an, an ancient Chinese city, using tiny outer space particles known as ‘Muon,’ which can penetrate hundreds of metres of stone surfaces.
What are Muons?
- Muons are subatomic particles that fall from the sky.
- They are formed when particles in the Earth’s atmosphere collide with cosmic rays, which are clusters of high-energy particles moving through space at slightly slower than the speed of light.
- Every minute, approximately 10,000 muons reach every square metre of the Earth’s surface.
- These particles are similar to electrons but 207 times more massive.
- As a result, they are also known as “fat electrons” at times. Muons are so heavy that they can travel hundreds of metres through rock or other matter before being absorbed or decaying into electrons and neutrinos.
- Electrons, on the other hand, can only travel a few centimetres. Muons are extremely unstable, lasting only 2.2 microseconds.
What is muon tomography, also known as muography?
- Muography is conceptually similar to X-ray, but due to the penetration power of muons, it can scan much larger and wider structures.
- Because these high-energy particles are naturally produced and abundant, all that is required is to place a muon detector beneath, within, or near the object of interest.
- The detector then counts the number of muons passing through the object from various angles to create a three-dimensional image.
Muons as well as archaeology
- The technique was first used in the late 1960s by Nobel Laureate and US experimental physicist Luis Alvarez, who collaborated with Egyptologists to search for hidden chambers in Giza’s Pyramid of Khafre.
- Nothing was discovered at the time.
Recent accomplishments
- In 2017, modern archaeologists repeated the experiment using more sophisticated and advanced muon detectors and made a significant discovery.
- The archaeologists discovered a previously unknown chamber at least 30 metres long by strategically placing detectors.
- It was the pyramid’s first major inner structure discovered since the nineteenth century.
Muography’s applications outside of archaeology
- Apart from archaeology, muography has found applications in customs security, internal volcano imaging, and other fields.
- After the 2011 earthquake and tsunami in Japan, scientists used the technique to look inside the Fukushima nuclear reactors around 2015.
- Because the site was highly radioactive, they placed the two muon detectors in 10-centimetre-thick boxes to protect them from radiation before scanning.
- Researchers are also using muography to study Mount Vesuvius, an Italian volcano.
Source: https://www.researchgate.net/publication/329546244_Applications_of_muon_absorption_radiography_to_the_fields_of_archaeology_and_civil_engineering