Wikipedia:Featured article candidates/Island of stability/archive1

The following is an archived discussion of a featured article nomination. Please do not modify it. Subsequent comments should be made on the article's talk page or in Wikipedia talk:Featured article candidates. No further edits should be made to this page.

The article was promoted by Laser brain via FACBot (talk) 22 January 2020 [1].

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Island of stability

Nominator(s): ComplexRational (talk) 14:42, 9 November 2019 (UTC)

This article is about the theoretical island of stability, a hypothetical set of superheavy nuclides (isotopes of the heaviest known chemical elements) that may be longer-lived than those currently known. This concept has guided research in the field of nuclear physics for decades, with various calculations corroborating predictions and numerous experiments designed to seek these nuclides. Although the island itself has not yet been discovered, experimental evidence strongly suggests its existence and that we are approaching the "shores".

After almost a year of work, a GAN in April passed by HaEr48, and a peer review in July-November by R8R (who contributed to the featured articles dubnium and tennessine, which partly lie within the same scope), I feel that this article is ready to be considered for featured status. Based on the reviews, I believe that it is complete and understandable despite the technical subject. All feedback necessary to complete the home stretch is welcome, so thank you in advance. Cheers, ComplexRational (talk) 14:42, 9 November 2019 (UTC)

Support by R8R

I first encountered the article at the peer review. At first glance, I liked the article very much and it only improved since then. I gave many comments during the review at PR and now that they are resolved, I believe the article is in a very good shape. I'll be happy to support its promotion but I'd like to give the article one last glance before then.--R8R (talk) 13:30, 10 November 2019 (UTC) My comments have been addressed, I am happy to support.--R8R (talk) 18:00, 11 November 2019 (UTC)

• Note a is better off split into two, with the "other observationally stable nuclides can be unstable" part better placed in a separate note after "252 nuclides are observed to be stable (having never been observed to decay)";

Split done.

• "by Yuri Oganessian et al. at the Joint Institute for Nuclear Research in Dubna, Russia" -- I previously recommended to use nationality and profession when first referring to a person to avoid any questions, even if just for a couple of seconds. In this case, that would be "Russian physicist Yuri Oganessian," but I don't think that a repetition of "Russian ... Russia" within a sentence could sound good. Will you be okay with "at the Joint Institute for Nuclear Research in Dubna, Russia, by Yuri Oganessian et al."?

Done, but I reworded it to avoid having et al. at the end of the sentence.

• "IUPAC defines the limit of nuclear existence at a half-life of 10⁻¹⁴ seconds" -- we haven't had this acronym so far, it's better to simply spell it out;

Done.

• "Heiner Meldner" -- I was about to suggest the usual nationality-profession introduction, but then I saw that the name had already been introduced. I think it would be better to refer to the man simply by his last name then;

Done.

• "Amnon Marinov" -- here, the rule is to be applied;

Done.

• "A 2018 study" -- it would be great to attribute that study to someone.

Now attributed to both the institution and first author.

There's no major issue that I was able to find.--R8R (talk) 15:10, 10 November 2019 (UTC)

All fixed, with slight modifications and adjustments for flow. ComplexRational (talk) 19:16, 10 November 2019 (UTC)

Sources review

The sources appear to be comprehensive and scholarly, meeting the FA criteria for quality/reliability. All links to sources are working, and formats appear consistent and MoS-compliant. The one issue I have is with problems of verification; in a number of cases, where the source document is quite lengthy, page numbers are either not given, are too wide to be useful, or in the odd case, incomprehensible. Here are a few examples:

• Ref 1: No p. refs given – the source has 30 pages
• Ref 2: The page range as presented is hard to decipher. I take it to mean "1250013-1 – 1250013-20", a 20-page range.
• Ref 17: page given as 03002, which is not a page number in this multi-page document
• Ref 18: No p. ref given – source has 40 pages
• Ref 19: Page no. 14201 is inspecific.

That's as far as I checked, but I imagine there are further examples – in fact, I jumped ahead and looked up the "Perspectives" document from the 2016 NUSTAR meeting (Ref 75). The document is 48 pages long, no p. refs provided. Specific page references, or short p. ranges, are essential for verification purposes.

I rechecked the references and adjusted the page ranges for as many as I could find, including all five examples above.

However, some are not as easy to verify because the page numbers in the open-access version (e.g. arXiv) may not be identical to the journal publication. I hope this is sufficient (those will also most likely be the pages checked by those interested in verifying). ComplexRational (talk) 19:44, 14 November 2019 (UTC)

I have since fixed or specified a few additional instances. ComplexRational (talk) 01:22, 15 November 2019 (UTC)

Otherwise, congratulations on a well-sourced and well-presented article. Brianboulton (talk) 16:02, 14 November 2019 (UTC)

@Brianboulton: Do you have any further comments or questions pertaining to sources? After these initial comments, I rechecked and made small corrections to as many refs as I could find; I now await additional feedback. ComplexRational (talk) 14:25, 28 November 2019 (UTC)

Sources now fine-no further issues. Good work. Brianboulton (talk) 19:38, 29 November 2019 (UTC)

Thank you for your review. ComplexRational (talk) 20:04, 29 November 2019 (UTC)

Comments by HaEr48 (Support)

I reviewed this article at GAR and I'm happy that now it's at FAC after a peer review and a lot of improvements. I want to thank the nominator and authors in advance for working on this topic. My review will be mostly from clarity and comprehensibility to a non-specialist audience. I'm not an expert so feel free to point out of I'm missing something obvious.

• The first sentence reads "In nuclear physics, the island of stability is a predicted set of superheavy nuclides that may have considerably longer half-lives than known superheavy nuclides": I think "nuclide" is a rather hard word for a lay person - is it possible to explain the concept using a different word, or to gloss a short definition in this sentence.

I substituted it with the more commonly used isotope, but there isn't much more that I can/should do in the lead than linking these terms.

• Is isotope a synonym for nuclide, or is it interchangeable in the context of the first paragraph?

Almost, but not quite. Nuclide can refer to any combination of protons and neutrons (e.g. superheavy nuclides), whereas isotopes are variants of a predetermined element with different numbers of neutrons (e.g. isotopes of hassium). When originally writing and reviewing, I did my best to ensure that their uses are precise; they should not be blindly interchanged, but they can be if the appropriate

• • Thank you for the explanation. HaEr48 (talk)
• the predicted closed neutron shell at N = 184: can something be linked here to improve comprehensibility? "Shell"? "Neutron shell"? "Closed neutron shell"?

Done – I did not originally do this because the link points to nuclear shell model, which is linked directly not much further down.

• confer additional stability towards fission, while also leading to longer half-lives towards alpha decay: Do "stability" and "longer half-lives" mean different things here? Or could we also more briefly say: "confer additional stability towards fission and alpha decay"?

Done – For the lead, a merge is suitable; I have done that. Later sections deal with the finer points.

• the successful synthesis of superheavy elements up to oganesson (Z = 118) in recent years : can we put a number for "recent years"? Since 2000? Since 2010? To make sure that the article won't be stale 20 years from now.

Not done – I'm open to ideas, but a few wordings I tried were quite clunky. Most discoveries were from the late 1960s onward, though no new element has been synthesized in the last 10 years; years are too precise, decades are clunky, and the "late (latter half of the) 20th century" is inaccurate.

• "Nevertheless, the successful synthesis of superheavy elements up to oganesson (Z = 118) in recent years demonstrates … " I assume the reason these synthesized elements don't count as the "island of stability" is because the lower number of neutrons. Is it possible to mention the maximum range of N that have been synthesized?

Partly done – This is correct, so I added the maximum number of neutrons reached (177), but the nuclide with both Z = 118 and N = 177 has not definitively been synthesized (the two heaviest known are Z = 117, N = 177 and Z = 118, N = 176). Does the current wording present this ambiguity?

How about something like: "the successful synthesis of superheavy nuclides up to atomic number 118 (oganesson) and up to 177 neutrons"? I'll defer to you regarding which is better. HaEr48 (talk) 18:19, 17 November 2019 (UTC)

• Introduction: Just to start, I want to say I like how the basic terms are laid out here
• while the approximately 3300 known nuclides: You haven't described what a nuclide is

Done – Added link and parenthetical definition as a (species of) atomic nucleus.

• with stability generally decreasing in heavier elements: If being "stable" is defined (in the same paragraph) as "never been observed to decay", what does it mean for stability to be "decreasing"? Isn't it just a yes or no attribute? Or if there is a definition of stability outside the yes or no question, please include it in this intro

It's not exactly a boolean quality, so I added a parenthetical definition relating stability to half-lives. I also added another footnote to clarify the meaning of decreasing stability.

• "The lower the barrier and the masses of the constituents": What "constituents" are we talking about here? The nucleons?

This refers to fragments into which a nucleus can fission. I reworded and linked this.

• In heavier nuclei, larger numbers of neutrons are needed to reduce repulsion and confer additional stability: Is this because neutrons are also involved in strong force? If so, suggest explicitly mentioning

Partly done – I noted that neutrons are uncharged (thus they do not repel other particles), but explicitly mentioning this here is not really necessary. The links should be sufficient; the strong force indeed affects neutrons just as it affects protons.

• " an upper limit was estimated around element 104" do we know who estimated this?

Not done – The source describes it as a view of the scientific community at the time, not an individual's or a group's theory.

• "and later, it seemed that element 108 might be the limit" Do we know the year of this estimate?

Yes, we do – I added from the source: it's around early 1960s, but no exact date is given.

More to come as I am still reading. HaEr48 (talk) 17:13, 15 November 2019 (UTC)

@HaEr48: I reviewed these first points, and made several changes. I feel that most of this does provide extra context, but a few details are too off-topic, so I believe that short parenthetical definitions combined with links should be sufficient. I await your additional feedback. Cheers, ComplexRational (talk) 00:01, 16 November 2019 (UTC)

• "The possible existence of superheavy elements with atomic numbers well beyond that of uranium" : why is uranium used as the comparison ? e.g. as opposed to the last element of actinides (according to the definition given in Superheavy element, actinides are the limit of "superheavy elements").

Done – I noted why this is relevant – until 1940, U was the heaviest known element.

• "In the late 1960s, more sophisticated shell models by American physicist William Myers and Polish physicist Władysław Świątecki, and by German physicist Heiner Meldner, taking into account Coulomb repulsion, changed the prediction for the next proton magic number from 126 to 114" …
  • why is Myers and Świątecki grouped in one clause but Meldner is mentioned in a different clause? Shouldn't it be "by Myers, Świątecki, and Meldner" in one clause?
  • does "taking into account Coulomb repulsion" belong to the more sophisticated model or to the prediction change?
  • Who proposed the prediction change?
  • Maybe this sentence can be split which would probably clarify my questions above?

The tricky part is introducing Myers and Świątecki who are of different nationalities but were co-authors, and distinguishing their work from Meldner's independent work. Does the rewording answer any of your questions?

• " led to the emergence of the macroscopic-microscopic method which takes into consideration…" Do we know what the method is for? Is it a modelling method? Prediction method?

Done – It's a nuclear mass model.

• any nuclei reachable via such fusion-evaporation reactions: but "fusion-evaporation reactions" hasn't been explained before.

Done in response to the point below.

• I feel like a brief description of the strategy of these experiments should be added in/around the paragraph #2 of "Discoveries", so that readers have context when you explain the problems with these experiments

Done.

• "resulting in the synthesis of only a few short-lived atoms of the heaviest elements in each experiment" if these few short-lived atom could not be detected, how did we know that this was the case?

In the 1970s (the focal period of this paragraph), the decay properties of these elements were not yet known. I changed 'would' to 'might' in previous sentence to emphasize that this was speculative; we now know that they are short-lived but still detectable.

• "Despite these failures, new superheavy elements were synthesized every few years in various laboratories through light-ion bombardment and cold fusion reactions." I don't understand this. If we're saying the searches failed, how come the superheavy elements did get synthesized? Or, should it start with "eventually" rather than "despite these failures"?

I distinguished unsuccessful searches for long-lived nuclei (far beyond what was then known) and simultaneous discovery of shorter-lived nuclei of elements with lower Z. I hope it is easier to follow now.

• Link "light-ion bombardment" and "cold fusion reactions"?

Partly done – I found a suitable link for the former, but the only reference for the latter is a disambiguation page entry. As it is distinct from cold fusion (theorized to occur at room temperature), I might have to label this with a note instead of linking. How does this sound?

Addendum: in response to an earlier comment, there is now some more context for cold fusion.

If you could label it with a note it would be great, but given that context was given in the preceding passage I think it's optional now. HaEr48 (talk) 18:19, 17 November 2019 (UTC)

• "Deformed nuclei" section: if heavy nuclei are always deformed, and this shifts the magic numbers, why does the original magic numbers and the island of stability around N=184 still matter?

Done – I explicitly mentioned now that the island of stability is a phenomenon in spherical nuclei; the distinction between spherical and deformed, and their respective roles, should be a bit clearer now.

It is a bit clearer, but I still don't fully understand. Are these heavier nuclei sometimes spherical or sometimes deformed? Does it depend on something? To me, this sentence "superheavy elements do not have perfectly spherical nuclei" seems to imply that they're always deformed, and that would mean the spherical numbers would not matter anymore. But this is not the case, so what am I missing? HaEr48 (talk) 18:27, 17 November 2019 (UTC)

Still more to come. HaEr48 (talk) 17:07, 16 November 2019 (UTC)

I still am working on the other comments (fusion-evaporation and a few more historical details); I have to recheck the sources and compile something. Before (or even while) reading the rest of the article, could you please let me know if I have answered your questions, or if some comments need further attention? ComplexRational (talk) 02:49, 17 November 2019 (UTC)

I have addressed all of the above comments; I'm ready to continue. ComplexRational (talk) 17:36, 17 November 2019 (UTC)

@ComplexRational: Thank you so much for your response. Most of them clarified the questions that I have, for a few of them I just have some follow up comments that I marked in blue. I'll continue with the rest. HaEr48 (talk) 18:27, 17 November 2019 (UTC)

• Paragraph #3 of "Predicted decay properties": May I suggest adding one or two introductory sentences about beta decay and what it means to atomic number and number of neutron. I know probably anyone learned it at one point in high school or uni, but IMO a refresher wouldn't hurt here and will help understanding what follows.

Done.

• "at an abundance of 10⁻¹² relative to lead,[53] although [several factors] may inhibit their production in r-process nucleosynthesis: "
  • Does the 10^-12 predicted abundance already take into account those inhibiting factors, or does the value need to be adjusted even lower to account for it?

Done – It's explicitly 10⁻¹² in the source, but I rearranged this paragraph to make this less ambiguous.

• • Can we have a sense of how small this abundance is, e.g. can it reach the earth and be detected by experiment?

Done – I noted that the source mentions a possibility of detection in cosmic rays.

• neutron-induced or beta-delayed fission will become the primary reaction channels: do we have appropriate links for "neutron-induced" and "beta-delayed"? Maybe what a "neutron-induced fission" means can be inferred from what it sounds like, but not sure about beta-delayed. If no link exists, maybe short definition in parenthesis?

Done – No article or section links exist, so I added a short definition.

• a 2013 experiment, a group of Russian physicists led by Aleksandr Bagulya.. Curious that we know that there are exactly 3 nuclei, but we don't know their atomic numbers. Is there a simple explanation for we know the amount but not the atomic number. If it is simple, suggest adding the explanation in text.
  • how is it possible to know the age of individual nuclei? (but maybe this is outside the scope of the article)

Not done – Not really within the scope of the article; it is partially explained how we know the number (but that too is borderline irrelevant to this article), but not why the other values are so uncertain.

• it may be useful to describe in "Synthesis problems" briefly what "cross sections" means or what the value imply, e.g. in the first place when you mention "this reaction has low cross sections" you could add something like "therefore lowering the expected yield" (or whatever is more appropriate)

Done – but in an earlier section where the term is first mentioned.

• What do you think about renaming the "Synthesis problems" section into "Possible syntheses and their problems"? Because the section also describe the possible strategies for synthesis rather than just the problems. I'll defer to you though

Done – I like it better this way actually.

• may also undergo electron capture in addition to alpha decay: might it be a good idea to add "(turning a proton into a neutron)" after "electron capture"? To explicitly say what it means for neutron:proton ratio.

Done.

• higher neutron flux (~1000 times greater) : 1000 times greater than what?

Done – The comparison was to current reactors.

• properties of superheavy nuclei near the beta-stability line remain unexplored: what does "unexplored" mean here? Not yet observed?

Done – I rewrote the ending of this paragraph to explicitly state that no such nuclei are known and their properties are not consistently predicted.

• a shift away from mass equilibrium in the products: Is there a link for "mass equilbrium"?

Not done – No link available; the term is used in RS but I can't find a mention anywhere on WP.

Follow up – What does it mean then? Is it possible to add a short definition or note? HaEr48 (talk) 14:31, 20 November 2019 (UTC)

Done – Not sure if this is ideal, but I expanded the parenthetical content to clarify. ComplexRational (talk) 15:50, 20 November 2019 (UTC)

• " weaker proton shell or subshell closures" AFAIK we haven't mentioned subshell before. Is it possible to add a link?

Removed – I don't need to even mention subshells here; the sources mainly describe them as weaker shell closures anyway.

• What does "unbound" mean in "unbound resonance"? Clicking the link for Resonance (particle physics) does not help.

Removed – This wording was not great to begin with, so I rewrote these two sentences.

• heavier nuclei would lie beyond a fission threshold: is it possible to explain what "fission threshold" mean here? Limit before fission happens too rapidly?

Done – Does the short addition in that sentence explain it? (It is indeed a limit before fission happens too rapidly.)

Yes, that helps, thanks. HaEr48 (talk) 14:31, 20 November 2019 (UTC)

• a greater binding energy per baryon: greater than what?

Done – Greater than that of nuclear matter; I added a mention of this, but it is implied in the next clause.

• Can we include the source of data used in File:Island of Stability.svg? (either in commons or in captions)

Not done – I can't track the source down, and the author is inactive. Would it then be necessary to remove this image from the article?

• What's the difference between the left and right diagram in File:Next proton shell.svg ?

Partly done – I added a superficial distinction, namely that it depends on the model and energy levels within. A fuller explanation would require careful extraction from the source, and similar captions for the same image (e.g. in unbinilium) use technical terms that would not be understandable to the average reader, even with links.

Follow up – it still isn't obvious why there are two from reading the caption. May I suggest moving the superficial explanation to the first sentence, e.g. "Diagram showing energy levels of known and predicted proton shells (left and right show two different models)" or something like that. We just need to explain why there are two without delving into the detailed explanation. 14:31, 20 November 2019 (UTC)

Done – This is simple and clear enough, thank you. ComplexRational (talk) 15:50, 20 November 2019 (UTC)

• In File:Nuclear chart from KTUY model.png, I think it's useful to note that no color means short-lived isotopes. Otherwise I don't know what visual shape to look for regarding "Regions of increased stability are visible around ... "

Done.

I'm done with reading now. I'll probably still make small suggestions here and there as I re-read it. Thank you so much for your work in this excellent article. HaEr48 (talk) 16:26, 18 November 2019 (UTC)

Thank you very much for your feedback, HaEr48, and thank you again for emphasizing the importance of general readability. I addressed everything I could; this involved rewriting a few sentences and adding a few additional references, and I removed a few weaker bits that were better presentable in another way. Please take another look to ensure that no bits are missing, and that the prose still reads well top-to-bottom after this overhaul. ComplexRational (talk) 22:03, 19 November 2019 (UTC)

Additional comments (stuff I forgot to write before, rather than new issues after the overhaul):

• "Many physicists believe that the half-lives of these nuclei are relatively short, on the order of minutes or days. Some theoretical calculations indicate that their half-lives may be long, on the order of 100 years, or possibly as long as 10⁹ years.": Do we know which one of these opposing predictions are more commonly accepted?

Not really. While most of the more recent sources give values on the order of 100-1000 years, they are not all in agreement and no one is universally accepted. I think it's better (and more neutral) to leave it as is.

• 30 orders of magnitude greater than those of nuclei unaffected by the shell closure: just for my own understanding, this means 10^30 greater, correct?

Yes, that's correct. To make it clear for everyone, I linked orders of magnitude (time) at its first occurrence further up the page.

• "For example, the neutron-deficient isotope ²⁸⁴Fl (with N = 170) undergoes fission with a half-life of 2.5 milliseconds, and is thought to be one of the most neutron-deficient nuclides stabilized by shell effects." I don't get which property this is an example of. The previous sentence is about neutron shell closure increasing fission half-lives, but this example seems to be about a nuclide without filled neutron shell and with short half-lives?

It's an example for comparison: in this paragraph, nuclides at the shell closure, moving further away (where half-lives decrease), and finally beyond the point that fission barriers vanish completely. Also note that the cited source makes almost this exact statement; I feel its described implications makes it worthy of inclusion.

• "one of the most neutron-deficient nuclides stabilized by shell effects": is the stabilization (despite the neutron deficiency) because of the number of protons?

It's mostly the effects of the neutron shell closure (less so the proton shell closure); I made note of this.

I'm still rereading the rest. But so far it looks great. HaEr48 (talk) 15:44, 20 November 2019 (UTC)

I made one change to address the last two bullet points; I hope the meaning is more straightforward now. ComplexRational (talk) 22:56, 20 November 2019 (UTC).

• Support I think this article meets the FA criteria. It is certainly well-written, well-referenced and well-researched. I am not an expert in the area but the explanation appears coherent as well as consistent with the limited things I know about the topic. I have done all I could above to suggest changes that can make the article more accessible without being dumbed down too much, and I am happy with the nominator's responses. Thank you for this amazing work. HaEr48 (talk) 02:20, 24 November 2019 (UTC)

Support from Cas Liber

Taking a look now....

• Nuclides with a magic number of each are referred to as "doubly magic" and are more stable than nearby nuclides as a result of greater binding energies. - would adding a couple of examples here help?

Done – I added three fairly well-known examples.

• Does having "Z=" and "A=" add any extra meaning over saying "Atomic number of..." and "Atomic mass of" ? I feel the latter is more accessible.

After introducing these symbols and their meaning in § Introduction, I feel the text flows better with these symbols. This is the wording used in many of the sources, and I envision that writing this out every time could be rather clunky without making their meaning clearer.

That's cool. It's a long time since I have looked at material on this topic, and if that's the way it's presented and understandable then I am persuaded Cas Liber (talk · contribs) 00:22, 19 December 2019 (UTC)

Otherwise impresses as comprehensive and prose does best job as possible straddling accessibility vs accuracy. Cas Liber (talk · contribs) 12:36, 17 December 2019 (UTC)

@Casliber: Thank you for your review; it was indeed helpful. ComplexRational (talk) 15:46, 17 December 2019 (UTC)

SandyGeorgia

The lead of this article was absolutely a pleasure to read ... I did not have time to delve much further, but did quickly notice a few minor things ...

• he is credited with the first usage of the term "superheavy element" in a 1958 paper published alongside Frederick Werner ... alongside ? Can't it just be with ?

Done

• the diagram in the lead took me some time to sort ... I finally figured out that the boxes referenced in the caption were the tiny things that look like grid lines, I think? If that is correct, is there a way to make that more clear?

The one thing I found I could clarify is that all nuclei (not only the predicted ones) are shaded. I'm not sure if there's anything cleared than "boxed", though.

• Do another check for WP:NBSP (see my samples).

Done — I hope I got them all.

Sorry, that's all I had time for, very nice work. SandyGeorgia (Talk) 03:30, 19 December 2019 (UTC)

@SandyGeorgia: Thank you for these comments. I hope my answers are satisfactory. ComplexRational (talk) 22:13, 19 December 2019 (UTC)

Good enough! Best regards, SandyGeorgia (Talk) 22:21, 19 December 2019 (UTC)

Spot check for paraphrasing

The top match from Earwig’s copyvio detector turns up nothing of concern: [2].

The two sources I spotchecked reveal careful re-phrasing in the author's own words; these spotchecks do not turn up copyvio/close paraphrasing issues. Some of the text, though, is well above my pay grade, so I ask @R8R, Double sharp, and ComplexRational: to check these samples (below) for source--> text conformity:

• 1. Karpov 2012, [3]

• Article: The shell closure at N = 184 is predicted to result in longer partial half-lives for alpha decay and spontaneous fission.

• Source: The fully microscopic approaches predict the proton shell closure at Z = 120,14 Z = 126,15 or Z = 114,120,126 (see Ref. 16) depending on the chosen nucleon–nucleon interaction in meson field theory. The neutron magic number N = 184 is almost firmly predicted by different theoretical models.

• Article: In the center of the island, there may be competition between alpha decay and spontaneous fission, though the exact ratio is strongly model dependent.

• Source: Above my pay grade, asking others to provide the supporting text.

@SandyGeorgia: Here is the source text, from page 15:

Finally, the most stable nuclei (which should be β-stable) undergo α-decay or/and SF. This consideration of the decay modes sequence is rather natural and model independent. It explains the area of β⁺-decay found here. However, the size of this area depends on the nuclear masses and nuclear structure.

ComplexRational (talk) 15:14, 23 December 2019 (UTC)

• Article: … the nuclide 306Ubb is still predicted to have a short half-life with respect to alpha decay.

• Search of source does not produce 306Ubb; asking others to produce supporting text.

This was attributed to the depiction of ³⁰⁶Ubb in the charts on p. 12 as outside the 1 µs "boundary" – this value is significant as it demarcates the current limits of detection (as mentioned in the article). I added another source that more explicitly predicts a short half-life for this nucleus (a table entry on p. 53 of the pdf), but it should be noted that exact predictions vary considerably among different sources. ComplexRational (talk) 19:38, 22 December 2019 (UTC)

• 2. Bernis 1977, [4]

• Article: In the late 1960s, more sophisticated shell models were formulated by American physicist William Myers and Polish physicist Władysław Świątecki, and independently by German physicist Heiner Meldner. With these models, taking into account Coulomb repulsion, Meldner predicted that the next proton magic number may be 114 instead of 126.[31] ... Myers and Świątecki also proposed that some superheavy nuclei would be longer-lived as a consequence of higher fission barriers. Further improvements in the nuclear shell model by Soviet physicist Vilen Strutinsky led to the emergence of the macroscopic-microscopic method, a nuclear mass model that takes into consideration both smooth trends characteristic of the liquid drop model and local fluctuations such as shell effects. This approach enabled Swedish physicist Sven Nilsson et al., as well as other groups, to make the first detailed calculations of the stability of nuclei within the island.[31] With the emergence of this model, Strutinsky, Nilsson, and other groups argued for the existence of the doubly magic nuclide 298Fl (Z = 114, N = 184), rather than 310Ubh (Z = 126, N = 184) which was predicted to be doubly magic as early as 1957.[31]

• Source: The modern widespread interest in superheavy elements began in Berkeley in 1965 as a result of two independent developments.1 The first of these was the estimate by Myers and Swiatecki that the fission barrier of a superheavy nucleus should be several MeV high, and the second was the suggestion by Meldner that the next closed proton shell after 82 is 114. It had always been assumed before, in analogy with the case for neutrons, that 126 would be the next closed proton shell. … The repulsive Coulomb force, which becomes increasingly important for heavier nuclei, is responsible for shifting the proton shell closure from 126 to 114.

• Source: In 1966 Strutinsky developed an improved method for calculating the potential energy of a nucleus as a function of its shape,4 and he and his co-workers used this method to calculate the fission barriers of several superheavy nuclei. 5 … Strutinsky's method is a two-part approach, with the smooth trends of the potential energy taken from a macroscopic model and the local fluctuations from a microscopic model. A macroscopic approach such as the liquid-drop model describes quantitatively such smooth trends of the nuclear potential energy but not the local fluctuations, whereas a microscopic approach, such as the single-particle model, describes the local fluctuations but not the smooth trends. So, why not synthesize the two? This combined macroscopicmicroscopic method should then hopefully reproduce both the smooth trends and the local fluctuations. This method is described in detail in Ref. 3.

• Source: Subsequently, Nilsson and his co-workers applied Strutinsky's method to a modified harmonic-oscillator single-particle potential to make the first systematic survey of the expected stability of superheavy nuclei.6 Since then, several other groups have made detailed calculations with improved computational techniques and with improved single-particle potentials. The status of such calculations is reviewed in Refs. 3 and 7.

• Source: As early as 1957, for example, Scharff-Goldhaber2 had suggested the possibility of another region of relative stability at the doubly magic nucleus U~126.

I recommend that a physics editor spotcheck a few more sources for source --> text conformity, but I do not believe any additional paraphrasing checks are warranted-- skilled writer. SandyGeorgia (Talk) 15:25, 22 December 2019 (UTC)

@Headbomb, Ruslik0, and MaoGo: I am pinging the three of you I know from the Wikipedia:WikiProject Physics/Members. Happy New Year, and Felicidades para el 2020, MaoGo! This Featured article candidate has cleared most of its hurdles, but needs a wee bit of help to bring it over the line to Featured article. It is customary to do an extra-rigorous review on first-time FAC nominators, to make sure that the text accurately represents the sources, and that there are no copyvio or close paraphrasing issues. (Subsequent nominations from the same writers don't need to be so rigorously checked.)

I have checked already for copyvio and feel confident to say there is no such problem in the writing here. I have spotchecked a few of the online sources, as you can see just above the post here, but a bit more spotchecking to make sure that the article text accurately reflects the sources is needed.

If any of you have just a few moments to spare, I think you will enjoy the article, and it shouldn't take too much effort to pick a few random samples from the sources and make sure that source-to-text integrity is there. Thanks (and saludos!) SandyGeorgia (Talk) 22:36, 1 January 2020 (UTC)

Further spotcheck on hard print sources

Setting this section up to continue. ComplexRational, my plan then, is to randomly select some text cited to sources to which I have no access, and ask you to provide quoted text from the source supporting the text in the article. Are there any of the hard-print sources that you do not have at hand (having, for example, returned them to a library) so I can avoid those? SandyGeorgia (Talk) 17:11, 5 January 2020 (UTC)

@ComplexRational: did you see my question above? SandyGeorgia (Talk) 22:36, 5 January 2020 (UTC)

Sorry, I missed it earlier. I do not have the books by Emsley, Podgorsak, Satake, or Ebbing, so best we avoid those. Most of the other references are linked, so I either have them downloaded or can find another copy at the original source. ComplexRational (talk) 23:16, 5 January 2020 (UTC)

@ComplexRational: did you see my samples below? I need for you to fill in the text from the sources. SandyGeorgia (Talk) 14:13, 6 January 2020 (UTC)

@SandyGeorgia: I'll get them later today – I won't have much time until this evening to do a thorough analysis. ComplexRational (talk) 15:42, 6 January 2020 (UTC)

Here are three random samples; if you can add the supporting text please. SandyGeorgia (Talk) 23:00, 5 January 2020 (UTC)

SandyGeorgia Done. ComplexRational (talk) 03:21, 7 January 2020 (UTC)

• Hoffman 2000, p. 426

• Article says: Because the produced nuclei underwent alpha decay rather than fission, and the half-lives were several orders of magnitude longer than predicted, this event was seen as a "textbook example" of a decay chain characteristic of the island of stability, providing strong evidence for the existence of the island of stability in this region.
• Source says (unabridged): Thus, at long last, more than 30 years after predictions of the Island of Superheavy Elements in the mid-60s, we have, indeed, reached and even gone beyond the "magic" region around Z = 114 and N = 184! When this book was finished, just before Glenn Seaborg left for the Boston ACS meeting, where he suffered his terrible stroke on 24 August 1998, we assumed that all that was left to do was the final proofreading. Then came this fantastic climax to the search for the superheavy elements, a search that had been a prime goal for a large number of scientists, especially for Glenn. We only regret that he is not here to witness it with us.

It began in January 1999 with an alert that a Dubna/LLNL collaboration working at Dubna had observed a single decay chain in the bombardment of 244Pu with 48Ca that they felt could only be attributed to element 114! A first glance at their findings seemed to indicate that, indeed, they had made the long-awaited discovery. Their reported chain of three α-emitters, 30-s, 9.71-MeV ²⁸⁹114 decaying to 15-min, 8.67-MeV ²⁸⁵112 decaying to 1.6-min, 8.83-MeV ²⁸¹110 decaying to 17-min ²⁷⁷108 which spontaneously fissioned, was a textbook example of what was expected for a SHE decay.

No paraphrasing problem, but which numbers am I looking at to back the "several orders of magnitude longer than predicted"? SandyGeorgia (Talk) 01:13, 9 January 2020 (UTC)

I believe that the "minutes" are supposed to be the evidence given that the mean halflife of e.g known Copernicium isotopes is far less than a second, although if it is that it probably needs an explainer. Jo-Jo Eumerus (talk) 09:51, 9 January 2020 (UTC)

This also references a statement from Oganessian, 1999: The lifetimes of the new isotopes, in particular ²⁸⁵112 and ²⁸¹110, appear to be approximately 10⁶ times longer than those of the known nuclei ²⁷⁷112 and ²⁷³110. I added this second inline citation. ComplexRational (talk) 22:52, 9 January 2020 (UTC)

@SandyGeorgia: There was one other prediction of SHE stability by Oganessian that I added a few days ago. The prose now reflects both aspects. Can I expect any more comments, as the coordinators have not yet taken any action? ComplexRational (talk) 03:12, 20 January 2020 (UTC)

I think we have well established that you paraphrase well :) SandyGeorgia (Talk) 03:17, 20 January 2020 (UTC)

• Blatt, J. M.; Weisskopf, V. F. (2012). Theoretical nuclear physics. Dover Publications. pp. 7–9.

• Article says: If a nucleus can be split into two parts that have a lower total energy (a consequence of the mass defect resulting from greater binding energy), it is unstable. The nucleus can hold together for a finite time because there is a potential barrier opposing the split, but this barrier can be crossed by quantum tunneling. The lower the barrier and the masses of the fragments, the greater the probability per unit time of a split.
• Source says (abridged): Some nuclei are unstable against a split into two (or more) parts. Such instability occurs if the binding energy of a nucleus A is smaller than the sum of the binding energies of the two separated parts B and C. Then arises the question how the two parts B and C can hold together, even temporarily, to form the nucleus A.

If the two constituents B and C are brought together from infinite distance, the potential energy increases, mainly because of the Coulomb repulsion between two positive charges.

If the energy reaches a point higher than E_∞, but lower than the highest point of the curve, the nucleus A is unstable with respect to the split into B and C; the two parts B and C are held together temporarily by a potential barrier and form an unstable nucleus A.

The probability II (per unit time for the penetration) decreases with an increase in the height of the barrier and with an increase in the masses of the penetrating parts.

Nicely boiled down to two sentences! SandyGeorgia (Talk) 01:15, 9 January 2020 (UTC)

• Sarriguren, P. (2019). "Microscopic calculations of weak decays in superheavy nuclei". Physical Review C. 100 (1): 014309–1—014309–12.

• Article says: The possible role of beta decay is highly uncertain, as some isotopes of these elements (such as 290Fl and 293Mc) are predicted to have shorter partial half-lives for alpha decay; this would reduce competition and result in alpha decay remaining the dominant decay channel, unless additional stability towards alpha decay exists in superdeformed isomers of these nuclides.
• Source says (unabridged): Thus, T_α half-lives of the order of 10 s are expected in ²⁹⁰Fl, from 1 to 10 s in ²⁹³Mc, from 0.1 to 1 s in ²⁹⁴Lv, and from 0.01 to 1 s in ²⁹⁵Ts. These values are always lower than the corresponding T_β⁺/EC half-lives, and therefore β⁺/EC would be much slower than α decay in these nuclei, not competing with them. Only the β⁺/EC from superdeformed shapes with T_β⁺/EC half-lives around 10-100 s could have a chance to compete with α decay.

• Help me understand that "The role ... is highly uncertain" is not editorializing? Since the content is over my head, need a hand here. SandyGeorgia (Talk) 01:19, 9 January 2020 (UTC)

  The source is basically saying that beta decay may not play a role as some sources predict, but that some isomers may indeed be capable of such decay if the partial half-lives are comparable. In my opinion, this combined with a few short bits elsewhere resolves to "highly uncertain". ComplexRational (talk) 22:52, 9 January 2020 (UTC)

  I believe it might be a way to paraphrase "would be", but it probably needs a rework. Jo-Jo Eumerus (talk) 09:51, 9 January 2020 (UTC)

What exactly may need a rework? ComplexRational (talk) 22:52, 9 January 2020 (UTC)

To the Coords, I think we have ourselves here an editor with an astonishing ability to paraphrase technical concepts, and no evidence of even the slightest close paraphrasing or copyvio issue. It is unfortunate that we have not found a single topic expert (who had not previously worked on the article) to weigh in here (which means I can't support, because I only support articles that I thoroughly understand), but I think we should not hold up this nomination waiting for independent editors from the Physics Project to show up. SandyGeorgia (Talk) 23:16, 9 January 2020 (UTC)

@FAC coordinators: Comments? ComplexRational (talk) 15:32, 15 January 2020 (UTC)

Support from Double sharp

I gave the article a read through. It's an excellent read and there's nothing that jumps out to me at the moment, so you have my support too! Double sharp (talk) 05:37, 21 December 2019 (UTC)

Coord notes

Hi ComplexRational, a couple more things:

• There are several duplicate links in the article so pls rationalise -- you can install and run this tool to highlight the dups.

Done.

• More importantly, I gather this will be your first FA if successful so as well as the source review conducted above I'd like to see a spotcheck of sources for accurate use and avoidance of plagiarism or close paraphrasing; if one of the reviewers above would like to undertake, that's great, otherwise you can request the check at the top of WT:FAC.

Requested here.

Pinging @R8R, HaEr48, Casliber, SandyGeorgia, and Double sharp: if any of them would like to assist with this spotcheck, in which case a separate review may not be required. ComplexRational (talk) 14:02, 22 December 2019 (UTC)

Tks/cheers, Ian Rose (talk) 12:29, 22 December 2019 (UTC)

And thanks to you as well for these comments. ComplexRational (talk) 13:59, 22 December 2019 (UTC)

I can do this ... perhaps today. I will spotcheck sources available online; if anyone else wants to spotcheck some that I cannot access online, that would be helpful. SandyGeorgia (Talk) 14:11, 22 December 2019 (UTC)

Pinged three more editors above; will do more if no one shows. SandyGeorgia (Talk) 22:38, 1 January 2020 (UTC)

@SandyGeorgia: Nothing yet AFAIK from them three (even though they have edited since then). Would you like to wait a bit longer, or should we just work through these examples ourselves? ComplexRational (talk) 15:54, 5 January 2020 (UTC)

Yes, as I'm seeing everywhere, FAC just doesn't command the attention it once did :( Let's work through them ourselves. (I apologize that I am being torn many directions at the moment, with a potential arbcase looming, but please be patient with me as I have my hands full.) I will sometime today put up some samples, then, and if I need help verifying, ask you for same. Don't hesitate to ping me if I forget :( :( Best, SandyGeorgia (Talk) 16:25, 5 January 2020 (UTC)

On the other hand, perhaps those editors have pinging disabled? (Another reason I hate this darn newfangled pingie thingie :) Do you think it would be intrusive if I posted to their talk after I have pinged? Don't want to do something that might bring an angry reviewer to your FAC :) SandyGeorgia (Talk) 16:27, 5 January 2020 (UTC)

I would advise against it; I have seen them respond to pings before in other areas, so if echo indeed is working, it may seem like badgering. Thanks for asking, and don't rush (I've been quite busy myself and am actively doing two reviews outside FAC). ComplexRational (talk) 17:02, 5 January 2020 (UTC)

Image review

• All images appropriately licensed.--Sturmvogel 66 (talk) 00:20, 29 December 2019 (UTC)

JJE

So, interesting topic, let's see if I can provide any useful comment (for disclosure, the nom of this article is working with me on Talk:Coropuna which is my own future nomination). I see that some of the sources in here aren't used in the article (aside from these which don't treat with nuclear physics, of course); I take that these aren't significant omissions? Jo-Jo Eumerus (talk) 20:44, 5 January 2020 (UTC)

Aside from the fact that those not already in the article seem paywalled (i.e. I cannot read them), the abstracts suggest that they may be loosely related but are instead focused on the properties of nuclides intermediate between the stable "continent" and the island of stability. Maybe worth another article, but it doesn't fit with anything in this one, so I don't believe these omissions are significant. ComplexRational (talk) 22:34, 5 January 2020 (UTC)

• I have some concerns about the copyright status of File:Even Z alpha decay chains.png, File:Nuclear chart from KTUY model.png, File:Superheavy decay modes predicted.png and File:Island of Stability derived from Zagrebaev.png as "selection and arrangement copyright" (the particular ways the diagrams are arranged, with particular colours, boxes etc.) might apply in such cases. Yes, the half lifes and decay modes of isotopes are not copyrightable but the way they were arranged into a diagram can very well be [5][6]; I'll see if the Commons copyright experts @Jameslwoodward, Elcobbola, and Clindberg: know anything about such images.
• File:Next proton shell.svg, it seems like it's not on slide 36.

Thanks for pointing that out. It was actually on slide 30; I fixed this in the file description. ComplexRational (talk) 15:41, 6 January 2020 (UTC)

Jo-Jo Eumerus (talk) 09:55, 6 January 2020 (UTC)

Hmm. A close call, I think. I would be inclined to say that they are not copyrightable -- as a rule graphs can be and are often drawn by computer rather than manually. These certainly could be drawn by computer. Choice of color is not, I think, enough to give a copyright. I'll be interested to see what my colleagues say. .     Jim . . (Jameslwoodward) (talk to me) 13:54, 6 January 2020 (UTC)

I was also wondering about this – before uploading File:Nuclear chart from KTUY model.png, I discussed this with Double sharp who uploaded File:Superheavy decay modes predicted.png as PD for insufficient creativity. I would agree with this, as only raw data is depicted ("facts that were discovered"), which is not copyrightable. ComplexRational (talk) 15:41, 6 January 2020 (UTC)

Comment by Utopes

I don't plan on reading through the whole article at this time, but I wanted to leave my cursory comments at the least. This article would highly benefit through the use of subheaders and paragraph breaks. This article is structured like an academic paper, and while there isn't anything wrong with that, it's not easily readable. The paragraphs are touching 12 sentences in just one paragraph, but this number is treating semicolons as though they were periods, because this number can be easily manipulated with punctuation insertion and removal. Basically, I would like to see more subheadings at current paragraph breaks, and see paragraph breaks in general for those with at least 9 sentences. While this wouldn't change the content, it makes the article much more consumable. (I understand that articles on technical subjects exist. However, even these are able to be separated into more refined subtopics and allow for easier navigation and readability.) Utopes (talk) 04:30, 10 January 2020 (UTC)

@Utopes: I added a few extra paragraph breaks, but they only really help when there is a clear transition of focus. Do you believe any more should be added? ComplexRational (talk) 15:46, 10 January 2020 (UTC)

Good. A potential subheader could be warranted at "Predicted Decay Properties" but I'm not sure myself what to put in there. I added another paragraph break, but I'm satisfied with how the article has been split up. I'm still neutral about the FA aspect. Utopes (talk) 00:04, 11 January 2020 (UTC)

@Utopes: Should I expect further comments from you? --Laser brain (talk) 14:25, 17 January 2020 (UTC)

@Laser brain:, I don't plan on leaving any more comments. I just had an issue with the spacing of the article, which was fixed. The content being FA worthy was covered aptly by other editors. Utopes (talk) 23:10, 17 January 2020 (UTC)

• Closing note: This candidate has been promoted, but there may be a delay in bot processing of the close. Please see WP:FAC/ar, and leave the {{featured article candidates}} template in place on the talk page until the bot goes through. --Laser brain (talk) 12:40, 22 January 2020 (UTC)

The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.