What are muons? Why is it news?
According to a new study, scientists are looking at the fortress wall of Xi’an, an old city in China, by using muons, which are tiny particles from space that can go through hundreds of metres of stone.
Researchers used a method called muon tomography or muography, which uses muons to make three-dimensional images of large structures, to study a 14-kilometer-long rampart.
What are muons?
- Muons are subatomic particles that fall from space.
- In 1936, scientists found the muon in “showers” of particles created by cosmic rays.
- They are made when particles in the Earth’s atmosphere collide with cosmic rays, which are groups of high-energy particles moving through space just below the speed of light.
- It comes in two forms: the muon, which has a negative charge, and its antiparticle, which has a positive charge.
- These particles are similar to electrons but 207 times more massive. As a result, they are also known as “fat electrons” at times.
- Muons can move through rock or other materials for hundreds of metres before being absorbed or breaking down into electrons and neutrinos. Electrons, on the other hand, can barely travel a few centimetres.
- They are extremely unstable and last only 2.2 microseconds.
Muography, or muon tomography, is the process of scanning huge structures using the penetrating power of muons. Although muon tomography was developed in the 1960s, it has only recently achieved popularity among scholars, notably in archaeology. The first time it was used was in the late 1960s, when a Nobel Prize-winning physicist called Luis Alvarez collaborated with Egyptologists to search for hidden rooms in Giza’s Pyramid of Khafre.
It is basically the same as an X-ray, but because muons can go through things, it can scan much larger and wider structures. All that is needed is to position a muon detector beneath, within, or near the object of interest. The detector then counts the amount of muons passing through the item from various angles to create a three-dimensional image. The image is then compared to one of the “free sky” muon images. This number represents the number of muons that have been stopped. The final image is effectively a shadow of the object.
- Muography has been used in customs security, internal imaging of volcanoes, and other applications.
- After the 2011 earthquake and tsunami in Japan, scientists utilised the technology to examine inside the Fukushima nuclear reactors in 2015.
- Researchers are also using it to study Mount Vesuvius, an Italian volcano.