Charged pions decay into muons and muon neutrinos whereas neutral pions decay into gamma rays. However, no other muons, electrons, photons, or hadrons were detected. Fermi conducted important research in particle physics, especially related to pions and muons. Thus all muons decay to at least an electron, and two neutrinos. These interactions usually produce pi mesons initially, which almost always decay to muons. There are about 10 times more cosmic ray muons than neutrino-induced muons observed in IceCube. At first, the speeds of muons and neutrinos were compared. This is how the muons and neutrinos are produced in the air shower. Low-energy muons and protons, invisible in water, can be detected. The muon system is used to identify and trigger on muons in the events. In many practical cases, relativistic particles (e.g., cosmic-ray muons) are minimum ionizing particles. These high-energy muons are capable of penetration to considerable depths in water and soil. Muons are denoted by and antimuons by . The chances of the requisite "two" muons being present simultaneously are exceptionally remote. He also suggested the use of muons as a nuclear probe.