Physicists are interested in muons for several reasons, but mainly because they are a useful tool for finding cracks in the most consistent theory of physics so far, the standard model. Although finding cracks in this theory is not easy, some recent experiments at CERN and Fermilab suggest that muons could be a key to advancing our understanding of physics.
Muons are elementary particles that are only produced in high-energy collisions, such as those that occur in cosmic rays or particle accelerators. Moreover, they are unstable and disintegrate rapidly to give rise to other, more stable particles such as electrons and neutrinos.
Despite their importance in theoretical physics, muons also play a significant role in nuclear fusion. Muons belong to the family of particles known as leptons, which also includes the electron, electron neutrino, muonic neutrino, tau, and tauonic neutrino. Muons rotate in an orbit that is two hundred times closer to the atomic nucleus than the electron’s, making them ideal for nuclear fusion.
If we place a mixture of deuterium and tritium together with a muon in a container, the particle will take the place of an electron and will be much closer to the proton in the nucleus. This allows the muon to cause the fusion of a deuterium nucleus and a tritium nucleus, releasing a lot of energy without being consumed in the process. In fact, a single muon particle can be involved in up to two hundred fusions before disintegrating.
Despite the advantages of muon-catalyzed nuclear fusion, there are two major constraints that make it uneconomical from an energy standpoint. First, muons disintegrate after about two hundred fusions, which limits their use. Secondly, to obtain a muon, we need to invest approximately two hundred times the energy that we will obtain as a result of nuclear fusion. Therefore, although muons have an important role in theoretical physics and nuclear fusion, there are still many limitations that must be overcome before they can be a viable energy source.