Cosmic Ray Muon Tomography
What is Tomography?
Tomography refers to imaging by sections or sectioning, through the use of any kind of penetrating wave. A device used in tomography is called a tomograph, while the image produced is a tomogram. The method is used in radiology, archaeology, biology, geophysics, oceanography, materials science, astrophysics and other sciences
What are Muons ?
Muons are like electrons, though heavier and unstable. They possess unitary negative electric charge (-1) and a spin of 1⁄2. Together with the electron, the tau, and the three neutrinos, it is classified as a lepton.
Muons are produced when cosmic rays (fast-moving atomic nuclei from space) hit the atmosphere. Cosmic ray muons shower the earth at a rate of 1 per square centimetre per minute at sea level. Thousands of Muons pass through our body every day.
There have been studies on development of techniques of using these highly penetrating particles as a means of non-intrusive tomographic inspections. Cosmic Ray Muon tomography is a relatively new type of imaging process making use of high energy particles. There are many different techniques involving the use of high energy particles that can be used for imaging.
Why Cosmic Ray Muon Tomography was in news recently?
The current studies focus around the use of cosmic ray muon particles to inspect cargo containers for nuclear material. The fear (in America) that an atom bomb might enter their country in a shipping container or on the back of a lorry. The team led by Michael Staib of the Florida Institute of Technology is trying to develop a method of using naturally generated subatomic particles called muons to look inside places where such bombs or the nuclear explosives needed to make them.
The reason that muons might be useful for detecting nuclear explosives is that they are scattered more by heavy atomic nuclei, such as those of uranium and plutonium, than by lighter ones—even including relatively heavy elements such as lead. Clever electronics can tell the difference. Someone wanting to smuggle uranium or plutonium might shield their contraband from detection by a Geiger counter using lead. But that would be no shield against detection by muons. This is the basic theory behind the working of the Cosmic Ray Muon Tomography. The basic idea of muon tomography is to detect a muon before and after it travels through a volume that is to be imaged. Based on information measured and inferred from these tracks, a 3D image can be produced as well as other types of analysis to estimate what is inside.
