The Neutrino

<p><strong>The Field Guide to Particle Physics <br></strong><a href="https://pasayten.org/the-field-guide-to-particle-physics">https://pasayten.org/the-field-guide-to-particle-physics</a><br>©2021 The Pasayten Institute <a href="https://creativecommons.org/licenses/by-sa/4.0/">cc by-sa-4.0</a><br>The definitive resource for all data in particle physics is the Particle Data Group: <a href="https://pdg.lbl.gov/">https://pdg.lbl.gov</a>.</p><p>The Pasayten Institute is on a mission to build and share physics knowledge, without barriers! <a href="http://pasayten.org/heysean">Get in touch</a>.</p><p><strong>The Neutrino<br></strong><br>The tiny, neutral one - or neutrino - has caused a lot of consternation since its discovery.</p><p><br>As the positively charged proton has the neutral neutron, so too does the <a href="https://pasayten.org/the-field-guide-to-particle-physics/electron">electron</a> has a neutral partner, the neutrino. Unlike the proton or the neutron, which both interact via the all of nature’s forces, the neutrino only interacts via the weak force and gravity - making it truly hard to measure. They just don’t interact very often.</p><p><br>Vast swarms of neutrinos - or <em>neutrini</em> - are passing through the earth - through us! - all the time.</p><p>We can measure neutrini only because there are so many of them out there. Like electrons, neutrini are stable particles, and are generated all the time in nuclear reactions. Fusion in the core of the sun is a huge source of neutrini. So are the radioactive decays of heavy elements deep within the Earth. So is the nuclear fission in power plants. Even outer space is chockablock full of neutrini!</p><p><br>The neutrino comes in three flavors, each partnered with a charged lepton. The <a href="https://pasayten.org/the-field-guide-to-particle-physics/electron">electron</a> has its electron neutrino. The muon has its <a href="https://pasayten.org/the-field-guide-to-particle-physics/muon">muon</a> neutrino. The <a href="https://pasayten.org/the-field