Talk:Neutron

neutron "mean lifetime"
Perhaps this has been discussed already, but I've stepped in it just now...the controversy regarding the neutron's lifetime. There are discrepancies between the mean lifetimes of ultracold neutrons and "in beam" neutrons. Out of ignorance, I've just modified the numbers to the ultracold neutrons. We should decide what to do...and mention the controversy perhaps? I seek a consensus... Bdushaw (talk) 12:53, 1 April 2024 (UTC)

From the neutron lifetime article: "On 13 October 2021 the lifetime from the bottle method was updated to τ n = 877.75 s [13][1] increasing the difference to 10 seconds below the beam method value of τ n = 887.7 s [14][15]"...so our values should be updated. 10 s is no small number! Bdushaw (talk) 13:06, 1 April 2024 (UTC)
 * I took a stab at including a short paragraph on the issue...there does not seem to be much point in specifying a precise value for the lifetime just yet, given how the measured numbers are changing and conflicting! Bdushaw (talk) 13:42, 1 April 2024 (UTC)
 * The Particle Data Group value is the recognized standard and their value should be quoted. I updated the ref. However the current text has derived values so we have no idea if they are correct or not. Johnjbarton (talk) 15:12, 1 April 2024 (UTC)
 * But there is no "standard" value... The citation actually talks about averaging the "bottle" values with one of the "beam" values, but those values are different, hence shouldn't be averaged.  Meanwhile, both values seem to be changing year by year! Bdushaw (talk) 15:19, 1 April 2024 (UTC)

The reverse reaction
I'm deleting for the second time this claim: I believe the claim is correct but unreferenced. It is correct in the same way as "thing don't fall up" or "it's not dark when the Sun's out". If there is a reference that makes this point we should explain why it is significant. Johnjbarton (talk) 15:14, 1 April 2024 (UTC)
 * The reverse reaction, that is, the decay of a free proton to a neutron, is energetically disallowed, unless additional energy is provided, such as from a high-energy collision of a proton with an electron or neutrino.
 * I commented above already under "A sentence on "free" proton decay". You've been harping on "unreferenced", but, as I have already acknowleged above a couple of times, supporting much of this article with proper citations will be an ongoing, lengthy task.  I object to suddenly enforcing this standard just now without giving us the opportunity to work through this challenging problem.  (Otherwise you'll just delete large sections of the article...to no purpose) Bdushaw (talk) 15:25, 1 April 2024 (UTC)
 * FWIW I don't delete just because things are unreferenced. I do delete quite a bit of unreferenced material because the content is confusing and without a ref I can't fix it.
 * I think this paragraph is superfluous. A ref might explain what makes the statement significant and then I could change the content. But it does not have a ref. If one shows up the content can be returned with further explanation. Johnjbarton (talk) 15:52, 1 April 2024 (UTC)

Why half-life?
I removed the free neutron half-life value then @Bdushaw put it back. The references provide the mean lifetime. Calculating then adding the half-life makes the article error prone (see discussion above under topic The "free" neutron - half time'). More important it is confusing for readers. "Why are there two such numbers? Why are they different?" The half-life is extraneous information. If a reader needs half-life it can be up to them to convert. Johnjbarton (talk) 15:19, 1 April 2024 (UTC)
 * We seem to be working at cross purposes, which I am sorry for. I think it is worthwhile to include both values (mean lifetime and half-life) as a service to the reader; I disagree with the idea of having the reader calculate it for themselves.  It is not extraneous to the extent that readers may have encountered neutron "half-life" elsewhere and looked up this article for more information.  Recall the reader level is the general public; few will know how to calculate half-life from mean lifetime.  I'd be open to just including the value in the table at upper right. Or a brief sentence elucidating the difference.  Bdushaw (talk) 15:31, 1 April 2024 (UTC)
 * Yes, I think we are considering the same kind of reader. But I don't think "both" is service, but a confusion because now they have to ponder two things.
 * With only the value given in standard refs we are also aligning with standard practice. If a reader only knows half-life from another source, the link to mean lifetime explains the difference. Johnjbarton (talk) 15:48, 1 April 2024 (UTC)

Positron capture
I've been working on citations and find myself somewhat stymied for a citation on positron capture. Firstly, although the text in the article associated with the term seems to me correct, "positron capture" is mostly ignored by standard text and references, certainly insofar as giving the basic discussion given in the article. I find, e.g., online course pages with discussion of the reaction. This form of "beta decay" is certainly correct, but unobservable/non-existent in ordinary existence. However, it seems to play a non-negligible role in the stellar formation of the elements. See W.A. Fowler, "The quest for the origin of the Elements", Science, 226, Nov 23, 1984. Perhaps the topic is too far astray for this Neutron article and the whole thing should be removed. Requesting comment! Bdushaw (talk) 07:52, 9 May 2024 (UTC)


 * I looked around and also found little. It's possible that the positron-neutron reaction in stars has a different name. My suggestion is just to delete that sentence. If we find a source it can be added back. Johnjbarton (talk) 14:55, 9 May 2024 (UTC)


 * I've revised the paragraph, including the citation I gave above. I've removed much of the "improvisational" material.  Keeping the mention of "positron" capture in stars supports the mention of nucleosynthesis in stars in the lead (which the article does not yet seem to mention!). Partly, I have a remote association with Fowler, who won the Nobel Prize... Bdushaw (talk) 20:22, 9 May 2024 (UTC)