The Antineutron

<p><strong>The Field Guide to Particle Physics : Season 3<br></strong><a href="https://pasayten.org/the-field-guide-to-particle-physics">https://pasayten.org/the-field-guide-to-particle-physics</a><br>©2022 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><br><a href="https://pasayten.org/the-field-guide-to-particle-physics/antineutron"><strong>The Antineutron</strong></a></p><p>Like the <a href="https://pasayten.org/the-field-guide-to-particle-physics/antiproton">antiproton</a>, the antineutron is a composite particle made up of antiquarks. It looks a <em>lot</em> like the <a href="https://pasayten.org/the-field-guide-to-particle-physics/neutron">neutron</a>, and that’s pretty interesting because both of those particles have no electric charge!</p><p>The antineutron is made from <a href="https://pasayten.org/the-field-guide-to-particle-physics/up-and-down-quarks">two antidown quarks and an antiup quark</a>. The antineutron’s mass is a bit over 939 MeV, and the mass difference ratio between the neutron and the antineutron is essentially consistent with zero.</p><p>Because it’s electrically neutral, it is <em>really</em> hard to measure properties of the antineutron. You can’t really use electric or magnetic fields to confine, shape or cool collections of antineutrons in any meaningful way.</p><p>We don’t have a working measurement of the antineutron’s magnetic dipole moment. We haven’t really studied their decay. </p><p>Left to its own devices, the neutron decays in about 15 minutes to a <a href="https://pasayten.org/the-field-guide-to-particle-physics/proton">proton</a>, and <a href="https://pasayten.org/the-field-guide-to-particle-physics/electron">elec