Talk:Neutron

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Former good article nominee Neutron was a Natural sciences good articles nominee, but did not meet the good article criteria at the time. There are suggestions below for improving the article. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake.
June 16, 2012 Good article nominee Not listed
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GA Review[edit]

This review is transcluded from Talk:Neutron/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: StringTheory11 (talk · contribs) 04:46, 14 June 2012 (UTC)

I will review this article. StringTheory11 04:46, 14 June 2012 (UTC)

I am sorry, but I will have to quick-fail this article due to a SEVERE lack of sources and bad prose. I feel that I have to downgrade this article to a C, which I have done. StringTheory11 18:01, 17 June 2012 (UTC)

GA review – see WP:WIAGA for criteria

  1. Is it reasonably well written?
    A. Prose quality:
    B. MoS compliance for lead, layout, words to watch, fiction, and lists:
  2. Is it factually accurate and verifiable?
    A. References to sources:
    B. Citation of reliable sources where necessary:
    C. No original research:
  3. Is it broad in its coverage?
    A. Major aspects:
    B. Focused:
  4. Is it neutral?
    Fair representation without bias:
  5. Is it stable?
    No edit wars, etc:
    Requesting semi-protection due to vandalism
  6. Does it contain images to illustrate the topic?
    A. Images are copyright tagged, and non-free images have fair use rationales:
    B. Images are provided where possible and appropriate, with suitable captions:
  7. Overall:
    Pass or Fail:

A few preliminary points to work on:

  • There is a citation needed in the lead. This will need to be fixed.
  • The references in the "further reading" section are not complete.
  • Refs 1, 2, 8, 10-13, and 17 need to be more than bare URLs.
  • Many refs need access dates.
  • This article has many unreferenced paragraphs. I am of the opinion that every paragraph should have at least one reference before an article is a GA.
  • I would rename "sources" to "natural sources", and move all artificial source info into "production". Also, the section needs to be expanded.
  • Many subsections in "intrinsic properties" are too short to comfortably be sections. I believe that if a section only has one paragraph, it is not worthy of a section. Either expand these or merge then with other sections.
  • "Neutron compounds" should be a subsection of "intrinsic properties".

More to come later. StringTheory11 04:21, 16 June 2012 (UTC)

CPT violation[edit]

I would suggest to either remove or rephrase the sentences

The fractional difference in the masses of the neutron and antineutron is (9±6)×10−5. Since the difference is only about two standard deviations away from zero, this does not give any convincing evidence of CPT-violation.[1]

The reason is, that I find it somewhat missleading for the non-expert to read this value of (9±6)×10−5. If one is not familliar with the way of how confidence intervalls are build what a standart deviation is and does not read the lengthy article linked to in the next sentence this gives a wrong impression. It would maybe be helpful to write something like, that this does not show that this value is non-zero and hence does not allow to conclude that CPT symmetry is absent. Regards, Falktan (talk) 20:40, 19 June 2012 (UTC)

References
  1. ^ K. Nakamura et al. (Particle Data Group), JP G 37, 075021 (2010) and 2011 partial update for the 2012 edition

Interactions[edit]

It says one of the interactions is Electromagnetic, but it's neutral and not affected by the electromagnetic force. It's composed of quarks that are, but it's a neutral particle. ScienceApe (talk) 19:44, 20 June 2012 (UTC)

I think thats ok: The neutron has a magnetic dipole moment and hence interacts with magnetic fields. Regards, Falktan (talk) 12:01, 21 June 2012 (UTC)
What does that mean? ScienceApe (talk) 16:44, 21 June 2012 (UTC)
It means that each neutron acts like a little magnet. Put it in an inhomogeneous magnetic field (one that has a gradient) and it will experience a force. That's an electromagentic interaction. SBHarris 20:34, 21 June 2012 (UTC)
So then by implication it should be possible to collimate neutrons into a beam correct? ScienceApe (talk) 20:28, 22 June 2012 (UTC)
In theory, yes. [1] It's been difficult in practice since the magnetic moment is so small. SBHarris 20:33, 22 June 2012 (UTC)

Neutron lifetime[edit]

The neutron lifetime should be updated as it was lowered by the Particle Data Group to 880.1 s. see: http://pdg.lbl.gov/2012/listings/rpp2012-list-n.pdf — Preceding unsigned comment added by 138.246.2.58 (talk) 10:06, 21 March 2013 (UTC)

It should also be mentioned that the two main methods for measuring neutron lifetime give apparently consistently inconsistent results, the current best results for the "beam" method being 887.7 ± 2.3 s, see http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.111.222501 --Ørjan (talk) 05:46, 3 December 2013 (UTC)

That's a ever-so-slightly eye-raising for physicists in the field, but it's certainly not much cause for a concern on Wikipedia. 880.1 ± 1.1s and 887.7 ± 2.3 s fall within about 2.2σ of each other. Headbomb {talk / contribs / physics / books} 06:01, 3 December 2013 (UTC)
Oh I see, you meant beam lifetime vs bottle lifetime. Yeah something could be mentioned about that I supposed. Headbomb {talk / contribs / physics / books} 06:01, 3 December 2013 (UTC)

How does the quark structure model quantitatively account for the neutron lifetime?--188.26.22.131 (talk) 10:31, 3 December 2013 (UTC)

For something "ever-so-slightly eye-raising for physicists in the field", the paragraph in PDG sounds rather desperate. They "once again call upon experimenters to clear this up" and they are clearly unhappy with not having been able to quote a satisfactory interval since 2006. If you are happy to quote "just under 15 minutes", the problem goes away of course, but you cannot then quote "881.5±1.5 s" in brackets as if the 1.5s were just a regular standard deviation. The value is given with the rather unusual qualification of "we can think of nothing better to do" and "Note that the error includes a scale factor of 2.7. This is a jump of 4.2 old (and 2.8 new) standard deviations. This state of affairs is a particularly unhappy one, because the value is so important."

Under "mean life time", it should be noted that "the state of affair is a particulalry unhappy one" because experimenters for close to a decade haven't been able to decide whether the lifetime is about 880 or about 885 seconds. --dab (𒁳) 12:03, 18 January 2014 (UTC)

Magnetic field influence[edit]

The article should mention if there is some influence on neutron lifetime by magnetic fields. (a neutron beam in magnetic field for instance)--193.231.19.53 (talk) 10:11, 7 January 2014 (UTC)

Thermal Neutron[edit]

The comment:

"thermal neutrons have a much larger effective cross-section than faster neutrons"

does not appear to be correct. This is insinuating that the cross-section is a property of the neutron. The cross-section is a property of the material whereas the effective relative velocity between the neutron and the target nucleus changes the cross-section. This is most easily reflected in the 1/v dependence, save for nuclear resonances. — Preceding unsigned comment added by Jesse.johns (talkcontribs) 00:51, 30 November 2013 (UTC)

The cross section is a property of the SYSTEM of particles, not either alone. I will fix it. SBHarris 06:45, 3 December 2013 (UTC)

De-(un)-archiving[edit]

Arhive 2 of this talk page has not many valid reasons to exist, most of it is relevant to present discussions, it should be unarchived, but I don`t know how.--188.26.22.131 (talk) 10:02, 3 December 2013 (UTC)

All these discussions are stale and several years old. If you have specific comments, feel free to unarchive specific threads (like I did below), but the bulk of these discussions should stay archived. Headbomb {talk / contribs / physics / books} 13:45, 3 December 2013 (UTC)

Magnetic moment[edit]

Un-archived from /Archive 2 on 3 December 2013.

How is explained the nonzero magnetic moment of the neutron, unusual for a electrically neutral particule?--MagnInd (talk) 10:24, 6 August 2010 (UTC)

Neutrons are not fundamental particles. They have electrically charged quarks inside of them. Dauto (talk) 15:25, 30 August 2011 (UTC)

How about Rutherford model? How do the models account quantitatively for the observed magnetic moment of the neutron in comparison one to the other?--188.26.22.131 (talk) 10:14, 3 December 2013 (UTC)

Is there any published comparative quantitative explanation of the magnetic moment by quark model and Rutherford model to decide which one is best? Or at least just of a quantitative account of the magnetic moment by the quark structure model?

I'll rephrase my edit to my first edit, whithout the claim of experimental support for Rutherford model, to which I understanding user Headbomb objects.--188.26.22.131 (talk) 10:29, 3 December 2013 (UTC)

This material simply is unfit for Wikipedia. First you say Rutherford's model is derelict, then follow up with a "well the jury is still out on this". Rutherford's guess was made at a time when no one knew of quarks, he did the best with what he had around at the time. But the jury has been in on this for 50+ years, and what accounts for the neutron's magnetic moment are the intrinsic magnetic moment of quarks. See doi:10.1007/BF02760010 and references therein. Headbomb {talk / contribs / physics / books} 13:31, 4 December 2013 (UTC)
I haven't said is derelict, just considered so. A more cautious phrasing is needed. The issue in discussion here is not wether or not neutron is made of quarks, but the explanatory power of structure models formulated over the time since the prediction and discovery of the neutron.--188.26.22.131 (talk) 10:55, 16 December 2013 (UTC)

text/reply brought from Wikiproject Physics:

Has anyone any objection to the above proposal of a more cautious wording?--193.231.19.53 (talk) 10:00, 17 December 2013 (UTC)
Yes. The Rutherford model explains nothing because it is wrong. Headbomb {talk / contribs / physics / books} 15:08, 17 December 2013 (UTC)

end of brought text — Preceding unsigned comment added by 188.26.22.131 (talk) 14:18, 20 December 2013 (UTC)

I have noticed this discussion and also the article proton spin crisis which I understand is an unsolved puzzling problem. Is there an article that tries to treat proton spin crisis based on quark structure of the proton?
As a remark, it appears from the Nuovo Cimento source that the quark structure model create more problems than it solves. It would interesting to see if there is a calculation of magnetic moment of the neutron based on the Rutherford model. If there is, a comparison between the models in regard to explanatory power would be useful.--193.231.19.53 (talk) 09:51, 5 December 2013 (UTC)
Only a quantitative comparative test of the explanatory power of two structure models would allow the categorical conclusion that neutron consist of quarks, if the quark structure has a better quantitative explanatory power. It seems that a comparative test of the two models has not been done. Therefore both structure models should be presented in the article.--193.231.19.53 (talk) 11:04, 10 December 2013 (UTC)
No. That neutrons are made of quarks has been established since the 1960s. Please stop wasting editor's time. Headbomb {talk / contribs / physics / books} 14:23, 10 December 2013 (UTC)
This is not waste of time, it is a legitimate aspect of scientific investigation procedure, by another name an application of the scientific method. The claim that neutrons are made of quarks has been established since the 1960s has little scientific support from the point of view of exaplanatory power. I have asked you if you aware of data regarding magnetic moment of quarks. You have rather dismissed the issue on a rather superficial analysis, so the quantitative account of magnetic moment by quarks is not very clear. The statement about the explanatory power of the two models should in the article. A clarification is needed, in the 1960s hypotheses about quarks were formulated, not established categorically.--193.231.19.53 (talk) 15:32, 10 December 2013 (UTC)
It is indeed a waste of time (see WP:CHEESE). The existence of quarks (and likewise that neutrons are made of quarks) has been established beyond a shadow of doubt since the late 1960s. Headbomb {talk / contribs / physics / books} 15:43, 10 December 2013 (UTC)
Comparing this discussion with WP:CHEESE is ridiculous.--193.231.19.53 (talk) 10:17, 17 December 2013 (UTC)
As stated above, the present discussion is not about wether or not neutron is made of quarks.--188.26.22.131 (talk) 10:58, 16 December 2013 (UTC)

text brought from Wikiproject Physics:

Rutherford's article from 1920 concerning prediction of a neutron has been brought to my attention long before the recent mention of someone like Santilli by Headbomb. If someone like Santilli considers worth buiding upon Rutherford's hypothesis, that is an entirely different aspect.--193.231.19.53 (talk) 10:09, 17 December 2013 (UTC)
There are a fair number of arguments that show that a neutron cannot be made of a proton+electron. Consider the following:
  1. Decay of a neutron yields a proton, electron, and an electron anti-neutrino. Now, maybe you could argue that the protron and electron are somehow "stuck together" in the neutron, but surely you agree that nothing can possibly confine the neutrino to the neutron? Remember, neutrinos are perfectly capable of penetrating light years of matter.
  2. Even the notion that a proton and electron could stick together is flakey, because of the Heisenberg uncertainty principle. It is quite simply inconceivable that an electron can be confined to the volume of a neutron.
  3. The electron is not subject to the strong force, so it can not be made to "stick" to the proton. Electromagnetic associations of protons and electrons are known as "hydrogen atoms".
  4. These arguments show that the electron and anti-neutrino could not have pre-existed as neutron constituents. The only explanation that makes sense is that the electron and the anti-neutrino were created during the decay event. Do you need more proof? I got more proof.
Stigmatella aurantiaca (talk) 00:00, 18 December 2013 (UTC)
As for arguments relating to the magnetic moment, see SSM Wong (1998), "Magnetic Dipole Moment of the Baryon Octet", Introductory Nuclear Physics, § 2.8, pp. 48ff, ISBN 978-0471239734  (or any other intro to nuclear physics textbook, really).Headbomb {talk / contribs / physics / books} 03:10, 18 December 2013 (UTC)
Wong ref--193.231.19.53 (talk) 10:32, 13 May 2014 (UTC)
It turns out that the quark model cannot account for neutron magnetic moment, just for the ratio of magnetic moments of proton and neutron.--193.231.19.53 (talk) 11:51, 13 May 2014 (UTC)

Neutron mass measurement[edit]

The article should present the methods for measuring the mass of the neutron and the (tacit) assumptions (if there are) involved in measuring.--5.15.206.141 (talk) 12:33, 3 January 2014 (UTC)

Well, today's edit by ‎188.26.22.131 tells us that The mass of a neutron cannot be directly determined by mass spectrometry due to lack of electric charge. So that's one way not to measure the mass. Now could someone please explain how it is measured, since the infobox does give a value to many significant figures? Dirac66 (talk) 03:13, 2 August 2014 (UTC)
Yeah, It is not only a way to measure the mass, it seems inapplicable on other grounds: mass spectroscopy seem to be a term used for measuring the mass of ionized atoms, not charged particles generally (although, ander a different name, the technique can be applied to charged particles). My point is that as phrased, it is not encyclopaedic, and I'd prefer to see the addition removed.
The earliest measurement of the mass of the neutron appears to have been done by Chadwick, by observing energies of reactants and products in a nuclear reaction (S. B. Patel (1991). Nuclear Physics: An introduction. p. 125. ). While this probably belongs in the historically oriented section § Discovery, it is clear that it is possible to measure the mass by analysis of interactions in which a free neutron is involved, through conservation of energy and momentum. Hopefully, someone with access to suitable material can add how this measurement is done in modern times. I expect, for example, that analysis of the observable decay products of cold neutrons would allow a fairly direct calculation, even given that the antineutrino escapes without measurement. (The total momentum starts as essentially zero, so the neutrino's momentum can be determined, hence its energy, so total initial mass–energy can be determined, since the electron and proton both have accurately known mass and their momenta can be measured directly.) —Quondum 14:49, 2 August 2014 (UTC)
The best modern values simply measure the wavelength of the capture gamma when cold neutrons are absorbed to protons in protium (light hydrogen) to make deuterium. It's a very sharp peak, since there is only one gamma emitted and this nucleus has no excited states. So you measure the wavelength of the gamma by crystal spectroscopy, and that gives its energy. You know the mass of the proton and deuteron by mass spectroscopy, and subtracting energy of gamma and proton from deuterium gives mass of neutron as residuum. There's a tiny correction for recoil kinetic energy of the D nucleus, which must be added back in. SBHarris 22:41, 19 August 2014 (UTC)
Neat. Would you be able to add this in? Even if it is unsourced, this description is an improvement on a negative statement about measurement of mass. —Quondum 23:30, 19 August 2014 (UTC)
Okay, I put it in. Byrne (2011) give values that are slightly more precise than 2011 CODATA for the mass in u, but slightly less precise than the CODATA for the value in MeV. It may be that since Bryne was doing his manuscript, CODATA came up with a slightly better u to MeV conversion, which is what limits the number of sig digits in Byrne's neutron mass in MeV. SBHarris 02:10, 21 August 2014 (UTC)
Thanks. That filled a definite hole in the article. —Quondum 03:06, 21 August 2014 (UTC)
I think a formula with the calculation of the mass of the neutron from the mentioned data should be put in article.--5.15.37.250 (talk) 21:17, 25 August 2014 (UTC)

Magnetic moment of an elementary neutron[edit]

I am puzzled by the discussion of the non-zero magnetic moment, which considers only the Rutherford model of the 1920s and the quark model of the 1960s which is now accepted. Historically there was a 30-year period, roughly 1934-1964, when the neutron was considered to be an elementary particle, and known to have spin 1/2 which excluded the Rutherford model. Quarks of course had not yet been thought of. So my question is: if a neutral elementary particle cannot have a magnetic moment, then how was the magnetic moment of the neutron explained during this period?? Dirac66 (talk) 02:36, 16 January 2014 (UTC)

Perhaps it wasn't explained at all, even the quarks at present have a weak explanatory power as can be seen from the mentioned source fron Novo Cimento. Or perhaps the Rutherford model has not been fully replaced until the conceptualisation of quarks.--188.26.22.131 (talk) 11:02, 27 January 2014 (UTC)
The neutron and proton magnetic moments to 3 sig digits, including the odd fact that the neutron moment is in the wrong direction from that of the proton (as though the neutron were a negative particle) was measured by Alvarez in 1940. And indeed he can't explain it. He simply says that present theory can't account for the magnetic properties of these particles. [2]
Although oddly, once the moments were known, theory could account for the moment of the deuteron, which is just the arithmetic sum of moments of the proton and neutron, both spinning in the same direction.
It would have been interesting if Alvarez had had the imagination to think of a neutron as a particle with a positive core balancing a negative "skin" so that a spin in the direction of the proton gave an opposite magnetic moment. Something fishy is going on inside the neutron, as Feynman says in his 1964 lectures. Later scattering experiments found just that (negative skin, positive core). And of course if you think of everything as particles, this implies negative and positive particles in neutron and proton.
BTW, although it is true that one early success of the quark theory was to predict the ratio of proton to neutron moments as -2/3 (which they very nearly are), there are many different quark models that give both proton and neutron moments correctly to 3 figures, and moments of heavier baryons as well. But all these models are a bit ad hoc, as you have to assume some physical model like harmonically oscillating quarks, or a bag full of quarks with complete freedom inside the bag and none outside. So people use the known moments to probe and deduce quark confinement and potential models, since there is a lot of freedom there. Depending on what you decide, you can predict any moment you like. SBHarris 05:13, 21 August 2014 (UTC)

Synthesis from proton and electron[edit]

What conditions are necessary for the occurence of synthesis of free neutron from proton and electron?--188.26.22.131 (talk) 15:41, 7 February 2014 (UTC)

Radius[edit]

What methods are there for determining the radius of a neutron?--188.26.22.131 (talk) 12:48, 28 March 2014 (UTC)

Per wp:talk page guidelines, please take this to wp:Reference desk/Science. - DVdm (talk) 12:51, 28 March 2014 (UTC)
But perhaps this question should be considered as a suggestion for addition of content to the article. A more correct phrasing would be Can we add a section to the article to consider what methods there are for determining the radius of a neutron? Dirac66 (talk) 15:45, 28 March 2014 (UTC)
Or, equivalently, should the article give some estimate of the effective size of the neutron? (e.g. effective density in a nucleus, average internal quark separation, etc.) Intuitively, there might be various measures of this, since it is not a point particle like an electron. Yet, at a glance, the article seems to make no mention of any size-related figure. —Quondum 17:46, 28 March 2014 (UTC)
Yes, I think the article should, and I'll try to spare some time to do that soon. Dan Gluck (talk) 14:40, 20 June 2014 (UTC)

Stability of neutrons in nuclei - wrong explanation in article?[edit]

I am not sure I agree with the brief explanation of why neutrons do not decay within nuclei. As was once explained to me, neutrons within nuclei do not decay to protons because of the Pauli exclusion principle - any newly created proton has no where to go, since all the spin states for protons are filled within stable nuclei. (Could go to a higher energy state, I suppose, if there was additional energy to allow it to be there.) Now that I think about it, the argument in the article suggests that all matter is unstable, since it suggests neutrons within nuclei would all rapidly decay to make all nuclei unstable... I would change the article, but its a little out of my field. Bdushaw (talk) 07:45, 14 August 2014 (UTC)

The explanation in the article is, in some sense, the same as yours, except that yours is stated in black and white. It is not a case of "has nowhere to go", but rather that it is energetically unfavourable. A slightly better, but still rather simplified picture is that if the decay were to occur, the new neutron proton would be in a "high pressure" environment. If the energy of decay is less than that needed to squeeze a new proton into the environment, it is energetically unfavourable. I think the article's use of "instability that would be acquired" is a poor choice of phrase, though. —Quondum 14:27, 14 August 2014 (UTC)
Which section are we discussing please? Bound neutron decay? Dirac66 (talk) 15:18, 14 August 2014 (UTC)
Yes, Neutron#Bound neutron decay is what I presumed was being referred to, being the closest thing I could find matching the description. The sentence fragment "the energetic instability of a single neutron to beta decay is balanced against the instability that would be acquired by the nucleus as a whole if an additional proton were to appear by beta decay" uses the term "energetic instability", which is not something with an obvious definition (to me). —Quondum 16:25, 14 August 2014 (UTC)

That's the section and phrasing that I was asking about. Surely the Pauli exclusion principle is relevant here? This property trumps the energetics of the situation, seems to me - there are no energy states within the nucleus that can accept another proton (usually, but not always). The explanation I heard was straight from the mouth of a professor of physics at UC Irvine. To back up a bit, a common question, and the one that I asked was, "how come the free neutron has a half life of 14 min. (or whatever), but a bound neutron is stable?" That was quite a while ago, but I don't think nuclear physics has changed that much since then. Bdushaw (talk) 20:45, 14 August 2014 (UTC)

I have looked into the question some more, and there seems to be a surprising lack of clarity on the question. On the one hand, the nuclear shell model - which I believe models the nuclei with protons and neutrons in quantum energy states - relies on the Pauli exclusion principle to lend stability to protons/neutrons in nuclei. On the other hand, other web pages make arguments based on energy alone - decay of a neutron bound within a nucleus to a proton requires more energy. At a more primitive level, one could model the whole nuclei by quarks and gluons, but I think that line of thinking is not necessary and doesn't help much. My intuition is still that any explanation must appeal to/or include the exclusion principle at some point - how can one avoid it? Web searches have not turned up a bullet proof reference on this issue; it may be a matter of finding the right nuclear physics book that has this discussion (I have Feshbach and de Shalit, but it is down in the basement somewhere). Bdushaw (talk) 18:47, 19 August 2014 (UTC)

Good explanations might be rare. Your two descriptions are complementary rather than mutually exclusive: the Pauli exclusion principle is the reason that the only available proton states have higher energy. Electrostatic repulsion also plays a part. This then leads to the result that in many nuclei, decay of a neutron can only proceed with an input of energy. —Quondum 21:13, 19 August 2014 (UTC)
Of course bound neutron decay does occur as beta-decay in some nuclei, 14C for example. I think a correct statement would be that a necessary condition for the occurrence of beta-decay is the existence of an available proton state at lower energy than the highest occupied neutron state. This has more tendency to be true in neutron-rich isotopes. Dirac66 (talk) 01:42, 20 August 2014 (UTC)
And both types of beta decay can happen in a single isotope. Example: copper-64 has one unpaired proton, and one unpaired neutron, so its problem can be solved in either direction. And in fact in this particular nuclide (though not all nuclides with this situation) is almost equally likely to decay by turning a proton (61%) to a neutron (positron emission), as to go the other way (39% beta emission). It makes a nice illustration of how things can be on the "fence" due to double pairing-instability. SBHarris 02:47, 20 August 2014 (UTC)

I've had a go at rewriting this subsection according to these nice examples above. I also added a brief mention of proton decay in the subsection above. See what you make of it; do what you will... Thanks for the nice discussion. Bdushaw (talk) 19:33, 23 August 2014 (UTC)

Thanks for doing the rewrite. I think the bound neutron decay subsection is now pretty good, and only needs a few minor clarifications such as specifying that an available proton energy state must have lower energy than the initial neutron.
However the mention of proton decay is more seriously flawed, in that it seems to confuse proton decay with inverse beta decay (positron emission). Actually proton decay is not analogous to the neutron decay discussed here; instead it is a completely different process which may take place on enormously long time scales (1034 years if at all), and does not even form neutrons which are the subject of this article. However Sbharris above did not actually refer to proton decay, but rather to positron emission, which is energetically forbidden in free nuclei but takes place on normal (human-compatible) time scales in some nuclei, e.g. 110 minutes in fluorine-18. Since this article is about neutrons, I think we should refer only to inverse beta decay (positron emission) by protons which is analogous to the beta decay of neutrons, and delete any mention of proton decay which has no analogy for free neutrons (because the neutrons disappear first by beta decay. I will make this change. Dirac66 (talk) 00:08, 24 August 2014 (UTC)

Feynman diagram is incorrect...[edit]

I've noted that the Feynman diagram is incorrect, since the antineutrino is traveling backward in time.... I think the direction of its arrow should be changed as the least confusing way to fix the problem. If the diagram is changed to correctly indicate a neutrino traveling backward in time it would likely confuse most people. Looking into the matter, this error was noted quite a few years ago with this particular diagram - there must be a correct one posted by now. I've had fun polishing various parts of this fine article, but I am tapering off now... See you later on wikipedia! Bdushaw (talk) 20:32, 24 August 2014 (UTC)

Two conventions exist, one where the outcome is explicitly labelled (νe, e), the other where the only the basic fermion type is labelled (νe, e), and you get particle/antiparticle from the direction of the arrows. Both are valid ways to label things. Headbomb {talk / contribs / physics / books} 21:18, 24 August 2014 (UTC)
I understand, but I don't have to like it... :) Bdushaw (talk) 07:21, 29 August 2014 (UTC)

Tweaked Introduction[edit]

I wandered off into the topics of nuclear astrophysics, etc. and then realized that this article was overly earth-centric, if you know what I mean. I've introduced nucleosynthesis in the introduction to emphasize that neutrons are not just something that happens on Earth/made by man. See how you like it. Bdushaw (talk) 07:21, 29 August 2014 (UTC)

The numerous articles having to do with this and a wide variety of similar topics are a bit of a mess, alas. Many of the articles ought to be combined, if you ask me, e.g., neutron capture nucleosynthesis, r-process, s-process all have separate articles. Similar with a wide variety of duplicating articles on nuclear reactions/processes/properties. There's a huge, thankless task... Bdushaw (talk) 07:21, 29 August 2014 (UTC)