Muon tomography or muography

Muon tomography or muography

Subject : Science and Technology

Context: Published in the Journal of Applied Physics, the study, ‘High-precision muography in archaeogeophysics: A case study on Xi’an defensive walls’, has been conducted by a team of scientists from Lanzhou University, China, and China Institute of Atomic Energy.

Concept:

What are muons?

• Muons are subatomic particles raining from space. They are created when the particles in Earth’s atmosphere collide with cosmic rays, clusters of high-energy particles that move through space at just below the speed of light. About 10,000 muons reach every square metre of the Earth’s surface a minute.
• Muons are tiny outer space particles that can penetrate hundreds of metres of stone surfaces. These particles have helped them find small density anomalies, which are potential safety hazards, inside the wall.
• These particles resemble electrons but are 207 times as massive, they are sometimes called “fat electrons”. muons are so heavy; they can travel through hundreds of metres of rock or other matter before getting absorbed or decaying into electrons and neutrinos.
• In comparison, electrons can penetrate through only a few centimetres. Muons are highly unstable and exist for just 2.2 microseconds.

What is muon tomography or muography?

• Muon tomography was first used in the 1960s, uses muons to generate three-dimensional images of such large structures.
• Muography is conceptually similar to X-ray but capable of scanning much larger and wider structures, owing to the penetration power of muons.
• As these high-energy particles are naturally produced and ubiquitous, one has to place a muon detector underneath, within or near the object of interest. The detector then tracks the number of muons going through the object from different directions, to form a three-dimensional image. 

Application:

• Muography has gained increasing attention from archaeologists as a novel and innovative tool to investigate large-scale archaeological sites. This approach may be especially helpful for identifying endangered cultural relics and monuments.
• Muography has found use in customs security, internal imaging of volcanoes and others. 
• It was Used in research of  Mount Vesuvius volcano in Italy,Fukushima nuclear reactors after the 2011 earthquake and tsunami in Japan,A muon detector, called CORMIS (Cosmic Ray Muon Imaging System), to examine the wall of Xi’an city. for hidden chambers in the Pyramid of Khafre in  Giza.