Leptons: Electron and Internal Structure Leptons Essay

Submitted By aminehr
Words: 1190
Pages: 5

Leptons in Life

Everything on Earth is made up of small particles called "matter". Atoms, made of electrons and nuclei bound by the electromagnetic force, make up matter. The electrons have negative electric charge, and their mass is exceptionally small compared to the nuclei, which are made up of protons and neutrons.
There are only two kinds of particles that are composed in the universe, viewed as the "elementary particles" of life. These basic building blocks of matter are leptons and quarks. Leptons were first discovered by J. J. Thomson, a British physicist, in 1897 and later theorized by several other scientists. They seem to have point-like particles without any internal structure Leptons can be individually observed and are subatomic particles, such as electrons, which are only affected by the electromagnetic force, the weak force, and the gravitational force, not the strong force. Protons and neutrons are made from "up" and "down" particles called quarks. Quarks were discovered and named by Murray Gell-Mann in 1964. Gell-Mann was an American physicist who received the 1969 Nobel Prize in physics on the theory of elementary particles. Quarks, similar to leptons, exist in three different generations having six flavors as well: up, down, charm, strange, top, and bottom. Also, quarks can exist in different quantum states. Protons and neutrons are each made up of three quarks and each quark has its own specific up and down spin, held together by the "strong force". It is the quarks that determine protons and neutrons. Quarks can only be found in whole states in normal circumstances and unlike leptons, they can be affected by the strong force. The strong and the weak forces cause particles to "spin", and are the reason why everything made up of particles stays intact. Leptons and quarks are the most fundamental constituency of matter in the universe. The word "fundamental" indicates that leptons and quarks cannot be cut up into other smaller substances, at least not with our current technology.
Being the fundamental particles in life, leptons are not composed of quarks or any other subunits within them. There are six different types of leptons, called flavors: electron, electron-neutrino, muon, mu-neutrino, tau, and tau-neutrino. Interestingly, each lepton flavor has its own size, but none of them show an internal structure. For example, the tau is 3,477 times larger than electrons. Leptons are classified by two categories: charged and neutral leptons. The charged leptons include the electron, muon, and tau. The neutral leptons are all the "neutrino" types. Additionally, each flavor has its own distinct mass. Electrons, being the lightest leptons, have a mass only 1/1,840 that of a proton making them the most stable lepton as well. Muons are heavier, having more than 200 times as much mass as electrons. The taus are approximately 3,700 times heavier than electrons. Fascinatingly, the tau barely manages to remain alive for a trillionth of a second, while the electron remains stable. In addition, taus are the only leptons that can decay forming themselves into hadrons. The "neutrino" types are leptons that have a charge of "zero". Although they are tiny, they have non-zero masses. Since they carry no electric charge, they are harder to detect as they travel like ghosts through normal matter. There are also "anti-particles" for each lepton. The anti-particles of leptons have the same mass but with opposite charge, i.e.: positron (e+), anti-muon (μ-), and anti-tauon (τ-). The flavors have a different feel of the weak force. Cosmic rays are the particle colliders used to detect high energy particle physics; both the positron and muon were discovered in cloud chambers. Leptons feel the weak force meaning they participate in weak interactions, and the charged leptons feel the electromagnetic force; none of the leptons participate in strong interactions. In other words, leptons do not interact with matter, they