Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Protonium
open-in-new
<p>Protonium (symbol: Pn), also known as antiprotonic hydrogen, is a type of <a href="/facts/Exotic_atom/FrPmnXvk">exotic atom</a> in which a <a href="/facts/Proton/clCjepXP">proton</a> (symbol: p) and an <a href="/facts/Antiproton/dLqJkhGQ">antiproton</a> (symbol: p) are bound to each other. </p><p>Since protonium is a <a href="/facts/Bound_state/NndW5JQl">bound system</a> of a <a href="/facts/Particle/JHKr2w6h">particle</a> and its corresponding <a href="/facts/Antiparticle/7Ic43ThI">antiparticle</a>, it is an example of a type of <a href="/facts/Exotic_atom/FrPmnXvk">exotic atom</a> called an <i><a href="/facts/Onium/85uteEFR">onium</a></i>. </p><p>Protonium has a <a href="/facts/Exponential_decay/wLB1zYDP">mean lifetime</a> of approximately 1.0 <a href="/facts/Microsecond/zdW1DEb2">μs</a> and a binding energy of −0.75 <a href="/facts/Electronvolt/YMT1fqX9">keV</a>. </p><p>Like all onia, protonium is a <a href="/facts/Boson/XtPFcjb5">boson</a> with all quantum numbers (<a href="/facts/Baryon_number/58MYGC3n">baryon number</a>, <a href="/facts/Flavour_quantum_number/RR7rsuTD">flavour quantum numbers</a>, etc.) and <a href="/facts/Electrical_charge/xxsBfmlB">electrical charge</a> equal to 0. </p>