NIPPON



 

A Japanese research team has succeeded in reaccelerating muons, a type of elementary particle, after artificially cooling them, in the first such breakthrough in the world.

The achievement is expected to help better re-examine the standard theory of physics that explains the movements of elementary particles forming matters and improve the accuracy of internal inspections of giant structures, according to the team of researchers from entities including the High Energy Accelerator Research Organization and the Japan Atomic Energy Agency.

Muons are created in large quantities when cosmic rays collide with the earth's atmosphere. Muons have characteristics similar to those of electrons but have a mass some 200 times greater.
 

 

Muons have a very high ability to penetrate materials, even bedrock several kilometers thick, and therefore are used for internal inspections for volcanos and pyramids, as well as for surveys of reactors at Tokyo Electric Power Company Holdings Inc.'s meltdown-stricken Fukushima No. 1 nuclear power station.

If the density of a material is high, the number of muons passing through it decreases, so it is possible to visualize the density distribution inside the ground and giant structures by analyzing the direction to which the muons flew and the number of the particles.