Talk:Curium/Archive 1

Curium: watts per gram correction
From the research I see curium 242 gives off 120watts per gram not 2! --BerserkerBen 03:14, 9 November 2005 (UTC)
 * Also http://aaa.nevada.edu/pdffiles/Microsoft%20Word%20-%20Task%2011%20QR%2001-2.pdf - more than I ever wanted to know about thermal effects in curium, but it's a nice reference and confirms the approx. 120 W/g for Cm-242, so I'll put it here. Femto 19:42, 10 November 2005 (UTC)

Natural?
There is a discussion at Talk:Periodic table, reproduced below. Lanthanum-138 (talk) 05:06, 27 May 2011 (UTC)

I am aware that most sources state that the number of elements found in nature is 94 (those with atomic numbers 1-94). However, several other sources raise that number to 95, and include americium (atomic number 95) to those elements found in nature. I hold a copy of "HUTCHINSON GALLUP Info 95" (Hellicon Publishing Ltd., UK, 1994) that states: "Of the [109] known elements, 95 are known to occur in nature (those with atomic numbers 1-95)" (page 459). Another source that includes americium to the elements that are found in nature is "The Free Dictionary by Farlex" that states: "[Americium] occurs in nature in minute quantities in pitchblende and other uranium ores, where it is produced from the decay of neutron-bombarded plutonium, and is the element with the highest atomic number that occurs in nature". This source can be found online here: http://encyclopedia.farlex.com/Americium-239 The above quote is reproduced in several other web sites, eg.: http://www.talktalk.co.uk/reference/encyclopaedia/hutchinson/m0009901.html Perhaps the confusion arises from two facts: 1) Quantities of americium (and curium) have recently been found in nature as a by-product of the operation of nuclear reactors and nuclear explosions (ref: http://www.hps.org/publicinformation/ate/q650.html). This, however, doesn't mean that americium cannot be found as a naturally occurring element as well. 2) Americium was first synthesized in 1944. The fact that it was synthesized before it was discovered as a naturally occurring element should not exclude it from the list of the elements that are found in nature. In fact, technetium and promethium are included in the list, even though they both have been artificially produced before they were found in nature. I would like to have some feedback on the topic. CostaDax (talk) 18:12, 15 February 2011 (UTC)
 * Americium is also found in nature
 * I can't access your "offline" sources, but the online one seems in order. So if you're certain of it, just be bold and change the table (Periodic table (standard)) to make Am's "natural occurrence" be "From decay". (Or maybe discuss it on the americium article's talk page as well.)--Roentgenium111 (talk) 15:35, 10 May 2011 (UTC)

Thanks, Lanthanum-138 (talk) 05:06, 27 May 2011 (UTC)


 * Although I'm not sure about this because 239Pu (which is what's usually meant by "neutron-bombarded plutonium") decays to 235U, not 239Am (which in fact decays to 239Pu). If they meant 244Pu, the only other natural isotope of plutonium, it does not decay to Am either, but to 240U and (occasionally) 244Cm. That creates:

244Pu --> 244Cm --> 240Pu* --> 236U --> 232Th and the rest is the beaten track of the thorium (4n) series.

* Or 240Pu --> 206Hg --> 206Tl --> 206Pb.

So if these (doubtlessly extremely rare) chains do happen, then only curium (Z = 96) would be naturally produced, not americium (Z = 95) Lanthanum-138 (talk) 05:21, 27 May 2011 (UTC)


 * This has also been posted at Talk:Americium. Lanthanum-138 (talk) 05:23, 27 May 2011 (UTC)


 * R8R Gtrs points out that 239Pu + 2 n → 241Pu → 241Am is possible (see Wikipedia talk:WikiProject Elements/Archive 11). However, "The Free Dictionary by Farlex" states that the naturally occuring isotope is 239Am and not 241Am. Double sharp (talk) 08:56, 30 January 2012 (UTC)

Stability characteristics
The isotope EO96Cu247 is reported to be the longest halflife isotope of this element. It would consist in 96 Deuterons plus 55 extra neutrons and a stability line characteristic of A = 3Z - 41. This atom could not have a balanced structure.WFPM (talk) 12:19, 28 May 2012 (UTC) It doesn't make sense that an even Z element would have an unbalanced EO isotope as its longest halflife isotope.WFPM (talk) 14:59, 4 June 2012 (UTC)

Last "somewhat stable" element?
Should it be mentioned that half-lives drop off very rapidly beyond curium? In a quick look through the Wikipedia pages for the following elements, I didn't see any half-life beyond 1000 years, more than three orders of magnitude below the half-life of Curium-247 listed in this article. -- 92.226.88.163 (talk) 01:17, 10 January 2013 (UTC)

Natural occurance
Curium has some rather long-lived isotopes. I have read from several sources that it probably exists in trace amounts in natural uranium deposits. It makes sense, but I am not sure if it is true. --Ferocious Flying Ferrets 19:32, 9 April 2010 (UTC)


 * It is reasonable to assume that it exists in nature, but the long lived isotopes should be primordial, and more short lived ones trace elements in natural ore. However, I believe it will be very hard to detect its presence, partially because of the atomic bomb tests. I presume the rumors are just reasonable speculation. Rursus dixit. ( m bork3 !) 12:12, 30 November 2010 (UTC)


 * It is interesting to note that the half lives of primordial Pu-244 (8.0 * 107y) and Cm-247 (1.67 * 107y) are comparable. So can we consider curium-247 to be primordial? Anoop.m (talk) 18:09, 6 March 2011 (UTC)


 * No, this factor-4 difference is still too large: primordial Pu-244 passed some 60 half-lives while Cm-247 had ~250 half-lives. So the ratio between present and original primordial Cm-247 would be of order 2-250≈10-80, much less than a single atom in the total Earth. OTOH, several atoms from each kg of original Pu-244 still remain.--Roentgenium111 (talk) 12:30, 3 June 2011 (UTC)


 * Correct – I missed that. And there's approx $1.33$ atoms in earth (Atom), meaning that if all Earth originally was made of Curium, then only 9th decillion ($9$) part of one Curium atom should remain. Almost zero, that is.


 * Primordial Curium is extremely improbable on Earth, unless a very improbable passers-by supernova got the improbable idea of improbably sprinkling it into the solar system some few million years ago. Rursus dixit. ( m bork3 !) 10:18, 17 July 2011 (UTC)


 * Uhhhh… but 244Pu only emits alpha particles (99.88%) or goes under spontaneous fission (0.12%). Also, 244Pu, despite the key source, is a synthetic nuclide, so 244Cm, and thus the element curium, is synthetic. That concludes our discussion. --3.14159265358pi (talk) 23:38, 5 December 2011 (UTC)


 * Pu-244 does occur naturally! And we're not talking about its decay, we're talking about what happens when it absorbs extra neutrons in very rich uranium deposits. Double sharp (talk) 02:44, 4 June 2012 (UTC)
 * Also, Pu-244 has a very rare (7.3×10−9%) decay mode of double beta minus decay to Cm-244. Double sharp (talk) 14:42, 6 July 2014 (UTC)

This article cites the only source I've ever seen claim that curium exists naturally, and it doesn't cite any outside source nor does it state that any natural curium has ever been detected. It's not implausible that it might occur in ultratrace amounts by neutron capture, but has there ever actually been any detection of it in nature, or of any other transplutonium element? If not, should Wikipedia be making this claim? - Bootstoots (talk) 18:09, 6 May 2015 (UTC)

Picture
Can we get a better picture of Curium? It's not that good quality. 00:44, 3 June 2015 (UTC) — Preceding unsigned comment added by Erbium Is Awesome (talk • contribs)
 * Well, it's not that easy to make it... Double sharp (talk) 07:02, 21 July 2015 (UTC)

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Use of curium as low-critical-mass nuclear fuel
A lot of this bit seems, from the comments on this talk page and the lack of cites on key sentences, to be a synthesis. Moreover, this page appears to contradict the article on Critical mass regarding the size of curium-245's critical mass, and according to said article a critical mass of any isotope of curium is not physically smaller than one of plutonium-239. All but curium-245's listed fission cross-sections also appear smaller than that of plutonium-239 given on the Neutron cross-section page, apparently contradicting the claim made that curium-247 would be "highly suitable" for use in miniaturised nuclear weapons.

I think the article (and potentially the others linked) might need some pruning/correction of synthesis and unverifiable/wrong data, but I'm not a nuclear physicist (or, for that matter, a particularly regular Wikipedian) and as such I feel unqualified to do it myself. But something smells fishy here and I think the matter could use some scrutiny from someone more qualified. Magic9mushroom (talk) 07:39, 16 January 2016 (UTC)

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So how is curium-250 produced?
The article certainly says how it is not produced (since 249Cm is likely to decay before it manages to capture a neutron), but not how it is produced. This, at least, indicates that it (like 257Fm, 255Es, 251Cf, and 254Cf) is preferentially produced in nuclear explosions; but does anyone still do this now? (With a long half-life of 8300 years, stockpiling it would be conceivable, although the neutron radiation produced by its predominant SF decay mode would be dangerous indeed.) Double sharp (talk) 15:45, 17 January 2018 (UTC)

Used for spacecraft?
I'm pretty sure that an isotope of Cm is used for spacecraft like the Voyager? — Preceding unsigned comment added by Porygon-Z474 (talk • contribs) 17:57, 28 November 2018 (UTC)