• Scientists are using outer space particles called muons to examine the fortress wall of Xi’an city, an ancient city in China.
• They used a muon detector, called CORMIS (Cosmic Ray Muon Imaging System), to examine the wall of Xi’an city.

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.
  • Atom is the smallest unit of matter and is made up of smaller units known as subatomic particles i.e. protons, neutrons and electrons.

Muons vs Electrons

• Muons are similar to electrons but weigh more than 207 times as much, equivalent to the difference between an adult person and a small elephant. Therefore, they are sometimes called “fat electrons”.
• Muons are so heavy, they can travel through hundreds of metres of rock or other matter in comparison, electrons can penetrate through only a few centimetres.
• Muons exist for only 2.2 microseconds before they decay into an electron and two kinds of neutrinos.

Muography

• Muography (or muon radiography) is a technique that exploits the penetration capability of muons. The measurement of their absorption in matter allows the imaging of the inner structure of large bodies.
• 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, all one needs to do is place a muon detector underneath, within or near the object of interest.

Applications

• Archaeology
• Detecting Volcanic Eruptions
• Nuclear Plants
• Application in various studies: Muons applications in studies of superconductors, molecular systems and chemical reactions, novel battery materials and a variety of organic systems.