Wikipedia:Reference desk/Archives/Science/2022 April 12

= April 12 =

Matter and antimatter
Has one already carried out a test of bringing together electron and positron beams in accelerators, rather than collision? I wonder if in this case there would be a pairing rather than an annihilation. It is the beta minus and beta plus decays that make me think that, because then one could imagine the proton composed of pairs of positron electrons, plus a positron to give a positive electric charge equal to the negative charge of the electron, then that the neutron would only be composed of positron electron pairs to remain neutral. In addition, it would give an equivalent number of matter and antimatter in the universe, which would simply have to be renamed as complementary matter. Malypaet (talk) 21:33, 12 April 2022 (UTC)
 * See positronium for the pair, dipositronium for a pair of pairs. Each of these is much lighter and bigger than a neutron. Graeme Bartlett (talk) 21:36, 12 April 2022 (UTC)
 * There needs to be enough antimatter mass (there isn't a lot around because it annihilates stuff) which has been created. See antineutrino, antihydrogen and https://en.wikipedia.org/wiki/Antimatter#Antihelium for the antimatter equivalents. Also there is free neutron decay into protons, electrons and antineutrinos, but neutrons are more stable when they are bound within nuclei. Modocc (talk) 03:00, 13 April 2022 (UTC)
 * I'm pretty sure that allowing particle beams to cross is a bad idea. Iapetus (talk) 10:17, 13 April 2022 (UTC)
 * I meant to say to cross with an angle close to zero and therefore collision energy close to zero, to see if in this case we still have annihilation or pairing. Malypaet (talk) 22:08, 13 April 2022 (UTC)
 * Okay. Alright, important safety tip. Thanks, Iapetus. --47.147.118.55 (talk) 06:14, 15 April 2022 (UTC)
 * Sorry, what are you on about with regard to the composition of the protons and neutrons? Protons are NOT made of "pairs of positron electrons, plus a positron to give a positive electric charge equal to the negative charge of the electron".  Likewise your odd explanation of neutrons.  Protons and neutrons, as you can clearly read at the relevant Wikipedia articles, are composed of quarks.  If you start with incorrect premises, you're going to arrive at nonsense conclusions.  -- Jayron 32 11:46, 13 April 2022 (UTC)
 * Yes I read wikipedia a lot, but I'm naive. So when I read there that a neutron which emits an electron and various objects transforms into a proton, the same goes for a proton which emits a positron and various to transform into a neutron, I find it easier to imagine these assemblies (lego! ) of electron/positron pairs, rather than quarks which lay the equivalent of an electron positron + various pair to bring a neutron back to its official mass. Besides, has anyone weighed the resulting neutron to verify that it has the official mass?
 * Who has seen a quark? And the muon which loses its electron (or muon+ its positron), no quark here? Malypaet (talk) 23:19, 13 April 2022 (UTC)
 * Also the electron proton collision can give a neutron Malypaet (talk) 23:29, 13 April 2022 (UTC)
 * Who has seen a neutron? All kinds of interaction of subatomic particles are possible, which can go any of several ways (see Feynman diagram), but are constrained by the conservation laws. One of the quantities that is conserved is charge, which works here: −1 + +1 = 0. Another conserved quantity is baryon number. The baryon number of a neutron is +1. The electron and positron both have a baryon number of 0, so they do not combine to form a neutron. --Lambiam 07:57, 14 April 2022 (UTC)
 * Per Lambiam, you've never seen a neutron, or an electron, or any of these particles. Saying that you find it easier to imagine things the wrong way doesn't actually make them correct, and per the GIGO principle, if you start with incorrect information, conclusions you draw from such starting places are going to be wrong. -- Jayron 32 17:08, 14 April 2022 (UTC)

I highly recommend reading Professor Matt Strassler's articles on particle physics. Here is the first of a series on why particles decay to produce other particles. This begins going into the properties of protons and neutrons. See "Articles" in the top of page for a full listing. --47.147.118.55 (talk) 06:14, 15 April 2022 (UTC)