Talk:Californium/Archive 1

Information Sources
Some of the text in this entry was rewritten from Los Alamos National Laboratory - Californium. Additional text was taken directly from the Elements database 20001107 (via dict.org) and WordNet (r) 1.7 (via dict.org). Data for the table were obtained from the sources listed on the subject page and WikiProject Elements but were reformatted and converted into SI units. --

Talk
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Accuracy dispute
The content that was previously listed in the history section was deleted due to reasons of (1) immateriality and (2) cause for undue alarm to present users of californium. If in the unlikely event the DOE halts californium production, only then should the deleted material be reinserted. —Preceding unsigned comment added by Integrity84 (talk • contribs) 23:39, 10 November 2008 (UTC)

It is quite regrettable that someone who wishes to cause undue alarm to users of californium-252 has hijacked this Wikipedia page and is spreading malicious untruths. The statement, “This will leave the Russian facility at Dmitrovgrad as the sole source of the radioisotope,” is simply untrue. It should in the very least be modified to say, “If this decision were upheld,…”. The unscrupulous hijacker goes on to write “…this is a primary driver behind the sudden cut-off”. Well, any informed person would know that there has been no cut-off from the DOE. The DOE continues to irradiate curium targets at its HFIR reactor to make into Cf 252, and they recently removed a batch for processing into Cf 252, to handle industry needs out through 2012. The likelihood that the US DOE will cease manufacturing Cf 252 is extremely low. In fact, if this hijacker had any integrity at all, they would say that the DOE admitted they had made a mistake in announcing that they were no longer going to manufacture Cf 252.

It’s unfortunate that the open environment of Wikipedia is vulnerable to such biased editing and to the underhanded tactics, in this case, of a vendor who is promoting neutron generators. The statement that “neutron generators have recently become cost effective” is another untruth. On an apples vs. apples basis, they are still 3-4 times more expensive than Cf 252, which is not close to being cost competitive. This sentence is nothing more than crass commercialism by a vendor of neutron generators, such as Sodern. I guess they’ve been infected by the negative advertising that dominated the recent US presidential race.

More importantly, if one views this discussion of recent events in the availability of Cf 252 (a small bump in a long road) against the rest of the content on this site, it doesn’t meet the test of materiality. Integrity84 (talk) 22:37, 7 November 2008 (UTC)


 * WikiProject Elements informed about this dispute. --mav (talk) 18:24, 8 November 2008 (UTC)
 * I don't see any references for the assertations, either by Knoxville Physics or by Integrity84. Wikipedia is not the place to speculate (either way) about the continued commercial supply of Cf-252. No sources = no dispute! Physchim62 (talk) 00:53, 18 November 2008 (UTC)

no resonoble sorces take it off the pagehenry (talk) 05:00, 22 November 2008 (UTC)

explosive decay
I've just been related a story from an ex-Soviet nuclear engineer. He said Californium was a problematic element to work with because it exhibits explosive decay; the element decays, splitting off a Helium atom (quite heavy), which given the rate of decay will quickly coat a room in radioactive dust. The attraction of it was it acted as a good calibration element, with a 2.5 year half-life, and it releases many neutrons when an atom splits. How do we add information like that to the article? Josh Parris &#9993; 00:24, 22 Jun 2005 (UTC)

en masse
The French phrase en masse has the connotation of "all together", that is, a group of people acting as one. It is not used to refer to "mass quantities" of a substance. Tex 20:06, 22 February 2006 (UTC)

expensive?
This Straight Dope link states that californium-252 is "the most expensive substance in the world". While this sort of rubbishy overstatement pisses me off excessively, does anyone think this should be in the article? If it's correct, that is... although Cecil and his minions usually are. &mdash; &mdash; riana_dzasta • t • c • e  • ER • 22:41, 6 July 2006 (UTC)

in a national geographic article (july '02) it said one miligram of californium 252 cost $68,000 (or $68,000,000 for a gram) Soyseñorsnibbles (talk) 03:28, 26 November 2007 (UTC)


 * The author of the Usenet Nuclear Weapons FAQ, Carey Sublette, explains why Cf-252 is so expensive to make in the last-but-one comment of this blog thread :
 * High atomic mass transuranics are created by multiple neutron captures, starting (ultimately) with U-238. To make Cf-252 this requires 14 successive captures.
 * The problem is: at each stage of this 14-step process the production rate is a fraction of the production rate of the previous product in the chain of captures. When you multiply the starting product production rate by a fraction fourteen times you end up with a very small number. To get significant amounts of product 14 you need very large amounts of starting material. To make grams of Cf-252 you need tons of starting material, plus years of irradiation in a high flux reactor.
 * The fuel grade plutonium makes a good starting material because it contains a relatively high concentration of Pu-242, which is already four steps along the production chain.
 * Rwendland (talk) 09:50, 26 November 2007 (UTC)

Industrial users pay approximately $100 US per microgram for Cf 252, as of summer 2008. This cost is expected to skyrocket at least three-fold if U.S. Department of Energy actually halts production. —Preceding unsigned comment added by 151.200.14.162 (talk) 20:26, 2 July 2008 (UTC)

can we agree that there are many sorces conflicting but yet we have no real source on the page time to take it offhenry (talk) 05:02, 22 November 2008 (UTC)

The claim should stay off the article, because it's hard to define and by many definitions not true. Antiprotons are vastly more expensive, though they aren't "sold", so to speak. A back of the envelope estimate gives their cost to be something like a quintillion dollars/gram (might be better at CERN now). Silpion (talk) 22:02, 25 October 2009 (UTC)

Im confused
I know that you cant obtain Californium naturally, but since you can artificially manufacture it, why is the appearance stated as "unknown" ? Forgive my ignorance but surely you can sneak a peek at it while it (temporarily) exists, cant you ?
 * As you probably know, most elements are known by their chemical compounds, not their pure elemental appearance. Fluorine, for example, is a good example: it took 74 years of determined effort to finally isolate pure fluorine in 1886. It is perfectly possible for an element's physical appearance to remain "unknown" even if it it synthesized as a compound with oxygen. --Vuo 15:38, 19 November 2006 (UTC)
 * A larger problem is that artificial elements are often not available in quantities large enough to see their appearance. --Itub (talk) 12:11, 26 November 2007 (UTC)

Uncited text
The below text needs to be cited before being placed back in the article. --mav (reviews needed) 02:35, 20 September 2010 (UTC)

Their neutron capture cross-sections are :
 * From the production section:

Thus californium-250 and californium-251 will be transmuted fairly quickly, with the majority undergoing nuclear fission at the mass 251, but with a large fraction surviving to become californium-252. The californium-252 will not be transmuted or destroyed quickly in a well-thermalized reactor, but it has a short decay half-life. These isotopes decay into long-lived isotopes of curium.

Californium-252 has a relatively high rate of spontaneous fission. Although still much less likely than alpha decay, this makes californium a significant neutron radiation emitter. Manufactured MOX fuel that contains enough curium would likely also contain enough californium after its use to preclude manual handling of the spent fuel, or its nuclear reprocessing products, with mere glove boxes -- that protects against alpha and beta radiation, but not against energetic gamma radiation and especially not against neutron radiation.

On November 1, 1952, the nuclear fallout of the world's first large hydrogen bomb test, the Ivy Mike test explosion at Eniwetok Atoll, in the Central Pacific Ocean contained detectable trace amounts of americium, curium, californium, berkelium, einsteinium, and fermium. These elements had been created by the repeated bombardment of nuclei of uranium and plutonium, and their products, by multiple neutrons during this nuclear weapons test, followed by multiple beta decays. Thus, amounts of element 92 were bootstrapped all the way up detectable amounts of elements 99 and 100. In the physics laboratories, the atomic numbers of these elements could be dermined by the characteristic X-rays that they produced when bombarded with energetic electrons - using the methods invented by Henry Gwyn Jeffreys Moseley in England over 30 years earlier.
 * From the occurrence section:

image
is File:Actinidesvsfissionproducts uncomp.png better than the template in use now? Nergaal (talk) 23:26, 26 September 2010 (UTC)


 * Not unless there is an image map b/c the table has clickable links. However, I'm half tempted to remove the table b/c its purpose and meaning isn't very clear. --mav (reviews needed) 03:43, 27 September 2010 (UTC)

Cf metal prepared or not?

 * This article might be of use here. Nergaal (talk) 22:31, 27 September 2010 (UTC)
 * Metallic Cf as thin films was prepared in 2010: . Nergaal (talk) 22:37, 27 September 2010 (UTC)
 * This book says that the metal was prepared as early as 1982. They even give a black and white image of a piece of metal. Nergaal (talk) 22:41, 27 September 2010 (UTC)
 * Thanks - I'll sort it out before the PR. --mav (reviews needed) 23:24, 7 October 2010 (UTC)
 * Sorting this out has been difficult. I ordered a book on the preparation of actinide metals that should be useful in sorting this out. --mav (reviews needed) 22:15, 16 October 2010 (UTC)


 * The preparation of the metal was presented in 1975: M. Noé, J. R. Peterson: „Preparation and Study of Elemental Californium-249“, in: Proceedings of the Fourth International Symposium on the Transplutonium Elements, Baden-Baden, 13.–17. September 1975, North-Holland Publ. Co., Amsterdam 1975. --JWBE (talk) 15:54, 18 October 2010 (UTC)
 * This says that there are two known allotropes: alpha and beta. The article also discusses about 10 compounds of Cf3+. Nergaal (talk) 21:30, 18 October 2010 (UTC)


 * All sorted now. The 1975 paper questioning the 1974 paper was a red herring. Several of my references still incorrectly say that Cf metal has not been prepared so I left a ref note to explain the whole mess. Somebody should check the German version of article to see if it needs to be updated. --mav (reviews needed) 14:40, 22 December 2010 (UTC)

Confusion?

 * Not to be confused with California.

Who are the person to confuse California with Californium? Neither an English speaker nor a foreign person proficient enough to read English. There is (AFAIK) no way to confuse the letter "a" with "u" followed by "m". They don't look alike. Rursus dixit. ( m bork3 !) 18:53, 14 November 2010 (UTC)


 * I agree, this warning is unnecessary. I'd remove it and just wikilink "California" in the lede text instead. --Roentgenium111 (talk) 18:06, 15 November 2010 (UTC)
 * I also agree and done. --mav (reviews needed) 04:29, 16 November 2010 (UTC)

Not in supernovae (I presume)
Using ADSABS here searching for californium and supernova I get some abstracts from 1956 and 1957 and one from 1959 explaining that the alleged Cf-254 decay is instead Fe-59 decay. Thereafter nothing! I believe that this alleged natural occurrence of Cf is a tall story originating from an obsolete theory on main energy production in supernovae. Given the low occurrence of Cf in atomic bombs, and the high occurrence of radioactive isotopes near the iron peak in supernova spectra, it is reasonable to assume that there is no Cf detected in supernovae (although the element may actually exist in trace amounts for a short while in layers that was near the core). Rursus dixit. ( m bork3 !) 12:36, 30 November 2010 (UTC)
 * I think it is more appropriate to call it a hypothesis, rather than a tall story. Mention of that unconfirmed hypothesis appear in publications as recent as 2007.&mdash;RJH (talk) 16:18, 30 November 2010 (UTC)
 * I see the refs in THIS article are all from 1956 as well. Looks like there's enough debate that we should specifically cite it as an ongoing debate, giving refs from 1956, the iron one from 1959, and whatever RJHall found from 2007. That should all go in this article, and then I'll go and move it all to footnoted controversy status in the other nuclide articles. Cf has been a royal pain, as it always causes the number of "elements naturally present on earth" (94 = 1 through 94 inclusive) to differ from "naturally detected in the universe" (95 = 1-94 + 98) which was always awkward. S  B Harris 18:45, 30 November 2010 (UTC)
 * Well, for example, this 2004 ref. mentions Baade et al. 1956 as an early suggestion for powering the light curves, and recommends Colgate, Freyer and Hand 1997 for a historical summary. Unfortunately I can't access the latter, but perhaps it's in a university physics library. The hypothesis is also mentioned in this 1973 and this 1978 ref.&mdash;RJH (talk) 21:09, 30 November 2010 (UTC)
 * A book Colgate, Freyer and Hand 1997 gives a nice overview.--Stone (talk) 23:59, 4 March 2011 (UTC)

I just added this text in a ref note at the end of the occurrence section. Please feel free to modify. --mav (reviews needed) 14:21, 5 March 2011 (UTC)
 * A 1956 paper reported that electromagnetic emissions possibly caused by the decay of californium-254 were observed in the spectra of some supernovae. This conclusion was challenged in 1959 and was subsequently regarded as incorrect due to a lack of californium-related decay products.

Neutron emission
The article now has the sourced statement "Each microgram of fresh californium[-252] produces 170 million neutrons per minute." However, a source from ORNL gives the rather lower figure of 2.314 million neutrons per second. They can't both be right. Anyone? Oliphaunt (talk) 21:53, 22 December 2010 (UTC)
 * I now see this same lower figure is used here, from another source. Oliphaunt (talk) 22:50, 22 December 2010 (UTC)
 * I went ahead and changed the past number/reference to the value/reference which you have provided - it does look much more reliable to me (peer reviewed, with accuracy) than the ANL page. Materialscientist (talk) 04:34, 23 December 2010 (UTC)

Tri-iodide
is said to be orange-red in de.wiki article, and it is correct according to this source. I failed to get snippets from two other sources in the article (or any other sources), which were supposedly saying it is lemon-yellow or pale-green or both, and thus just removed green to avoid article contradicting itself. Comments? Materialscientist (talk) 10:56, 14 February 2011 (UTC)
 * Fine with me. --mav (reviews needed) 22:26, 14 February 2011 (UTC)
 * Fine what, lemon or orange :-) ? Materialscientist (talk) 22:31, 14 February 2011 (UTC)
 * Yes :) j/k - I'll take a look at the refs. --mav (reviews needed)
 * Lemon-yellow it is per Jakubke page 166. I'll add the cite. --mav (reviews needed) 23:05, 14 February 2011 (UTC)
 * If questions arise, these colors not necessarily contradict: Cf is hardly available, thus samples are small. A thin yellow sample might look orange when thick or when it has too many (lattice) defects, which is not unusual - self-damage due to radiation. Materialscientist (talk) 23:15, 14 February 2011 (UTC)

Misidentified isotopes
In the introduction, it is Cf-249, not Cf-252, that has a half life of 351 years. Under Production, "curium isotopes 244 to 248 are irradiated by neutrons in special reactors to produce primarily californium-242" should obviously be californium-252. 69.72.27.179 (talk) 08:16, 21 February 2011 (UTC)
 * Fixed, thanks! (I believe the lifetime, not the isotope No was wrong in the introduction, as Cf-252 is produced more). Materialscientist (talk) 08:24, 21 February 2011 (UTC)

Neutron cross-section
Suggested link: Neutron cross-section. For the sentence "collecting neutrons (high neutron capture) and tendency to interact with other particles (high cross section)". Not added myself, as I might miss a subtle point here, and the neutron capture link is still useful. In particular, Neutron capture does what the Neutron cross-section article (which explains why scattering cross-section varies) fails to do - namely explain why certain nuclei are more likely to absorb neutrons than others. From what I can tell, it depends on the neutron energy and the resonance integral. Also, possibly more useful than cross section (physics) (currently linked) is the article nuclear cross section and/or the article absorption cross section (as opposed to scattering cross-sections).

What I am really looking for is an explanation as to why californium-251 has a lower yield than the other isotopes produced by neutron radiation of berkelium, and when I follow the links, it doesn't really help. It there a source that would be useful for further reading on this topic? Carcharoth (talk) 06:48, 12 March 2011 (UTC)
 * Link swapped but I'm not familiar enough with these concepts to provide an explanation for Cf's lower yield. --mav (reviews needed) 00:19, 10 May 2011 (UTC)
 * The yield seems to be lower for isotopes with an odd mass number (see File:ActinideExplosionSynthesis.png). Our articles claim that there is no such effect, and the even-odd variation is observed for the proton number only. There is some explanation to the mass-number change on page 44 here. It is relatively old, and something better should exist in the literature (an expert should know). Materialscientist (talk) 00:39, 10 May 2011 (UTC)

Unresolved issues to fix before re-submittal to FAC
It's on GA for the moment, since we've agreed that GA is higher than A on WP:ELEM. Lanthanum-138 (talk) 13:27, 9 April 2011 (UTC)

Lede

 * Isn't it half-life instead of "half life"?--R8R Gtrs (talk) 23:33, 26 March 2011 (UTC)
 * Yep - fixed. --mav (reviews needed) 17:07, 27 March 2011 (UTC)
 * "Element 118 was synthesized by bombarding californium-249 atoms with calcium-48 ions." If Element 118 links to ununoctium and even is ununoctium, shouldn't it be ununoctium instead, then?--R8R Gtrs (talk) 23:33, 26 March 2011 (UTC)
 * Good idea. Done. --mav (reviews needed) 17:07, 27 March 2011 (UTC)
 * Isn't ununoctium just a temporary name? Seems to me that "element 118" is more explanatory and conveys the idea that this is a little known element (actually, it barely exists at all, according to its article a total of three atoms have been created lasting less than a millisecond) while "ununoctium" is more obfuscatory, a name that is merely bastard Latin for "element 118".  Sp in ni  ng  Spark  22:37, 10 April 2011 (UTC)
 * Temporary yes, but it is the official current name. --mav (reviews needed) 00:22, 10 May 2011 (UTC)

Characteristics

 * If it reacts with hydrogen when heated, why is the reaction with "dry hydrogen" rapid? This seems like a discrepancy without further explanation.
 * I presume small amount of moisture will modify (oxidize) the surface of Cf and slow down the reaction. Many reactions stop by such surface layer, whereas pure dry hydrogen easily diffuses through and reacts with the bulk of a metal. Materialscientist (talk) 07:48, 6 March 2011 (UTC)
 * What are the products of the reactions named in this section?
 * The daughter article compounds of californium goes into that level of detail. I want to keep this section as a summary. --mav (reviews needed) 11:26, 12 March 2011 (UTC)
 * Fair enough. I've said a bit more about this below. Carcharoth (talk) 22:34, 12 March 2011 (UTC)
 * "Few californium compounds have been made and studied." - is it possible to have a rough range here? Less than ten? Less than 20?
 * Source does not say and is contradicted by another source with an equally useless statement saying that many solid Cf compounds have been prepared. Removed. --mav (reviews needed) 19:50, 27 March 2011 (UTC)
 * It is not clear here how you get from the samples of californium, freshly produced by the methods described later in the article, to the oxidation states being described here. When it tarnishes in air, for example, which oxide is produced? Ditto for all the other compounds named - how are they produced?
 * I'll try to find the bit about tarnishing, but in general that level of detail is really more appropriate for compounds of californium. --mav (reviews needed) 11:26, 12 March 2011 (UTC)
 * Could you say a bit more about where and how the line is drawn? Reactions involving californium as an element presumably get discussed here? If some of the oxides are produced from secondary reactions of compounds of californium, it would be nice to have something saying that (with the detail relegated to the compounds article), and to make clear in this article what the standard reactions are that involve californium on its own, i.e. the ones that produce the compounds that are used for later reactions. Ditto for the reactions that produce elemental californium - I think it was said somewhere that the metal form was produced by reduction from an oxide? Carcharoth (talk) 22:34, 12 March 2011 (UTC)
 * The line is drawn where the description turns to creating something related to Cf but not Cf itself. The point is moot anyway, because I just checked my two chemistry of the elements textbooks and the chemistry of the trans-actinides book and even they do not go into specific detail on the equations used to create Cf compounds; they describe the oxidation states w/o equations either. I strongly feel that that level of detail, even when a source for it can be found, is not appropriate for this article. --mav (reviews needed) 19:50, 27 March 2011 (UTC)
 * Is there a reason the 'Chemical properties and compounds' section uses "further information" and the 'Isotopes' section uses "main article"?
 * Because Compounds of californium is not supposed to be strictly an expansion of the chemistry and compounds section in this article; instead, the daughter article expands on just one part of the subsection here. Yet, that is the case for Isotopes of californium. --mav (reviews needed) 20:07, 6 March 2011 (UTC)
 * OK, though I've seen "see also" used at the top of sections. I've only rarely seen templates like that used at the end of sections. It just looks strange to me. I see no reason not to put all such "see other bit over here" pointers at the top of sections. i.e. my objection (and I wasn't clear on this) was more about the placement of the pointer template. I'm so used to seeing them at the top of sections that seeing one at the bottom of a section is jarring. Carcharoth (talk) 03:25, 7 March 2011 (UTC)
 * "One microgram spontaneously emits 2.3 million neutrons per second." - you link to microgram. Interesting as that article is, I'd much rather learn whether 2.3 million neutrons per second is a lot or not (it sounds like a lot). Also, is the energy range given for its neutrons high, low, or normal? i.e. Can the harmfulness of Californium-252 be compared to other radioactive isotopes. I realise it is not possible to do this if the sources don't say anything, but these are obvious questions readers will ask themselves.
 * In the same paragraph above that it says that Cf-252's strong neutron emission is part of what makes it extremely radioactive and harmful (with plenty of cites). So yeah, it is a lot. My sources do not give comparisons to other isotopes. The part about neutron energy is too technical and not useful w/o context, so moved to the isotopes article. --mav (reviews needed) 19:50, 27 March 2011 (UTC)
 * "3+ valence" "oxidation state +3" would be preferable, wouldn't it? Also, "oxidation states are IV (strong oxidizing agents) and II (strong reducing agents)" could go better with IV and II turned to +4 and +2, accordingly.--R8R Gtrs (talk) 23:33, 26 March 2011 (UTC)
 * Oxidation states can be represented by Roman or Arabic numerals but most often by Arabic. Fixed. Although, the Roman numerals are always used in chemical formula b/c that is the convention with coordination chemistry (relating to oxidation numbers) and there are cases where the two are different. Valence is not really equivalent; it deals with the number of bonds that can be formed and not the charge (already exlained in the article). --mav (reviews needed) 19:50, 27 March 2011 (UTC)
 * "curium ( Z = 96)" why Z is used? wouldn't it be better as "curium (atomic number 96)" or even "curium (element 96)"--R8R Gtrs (talk) 23:33, 26 March 2011 (UTC)
 * Less jargon while not reducing info = good. Done. --mav (reviews needed) 19:50, 27 March 2011 (UTC)

History

 * "Californium metal was first prepared in 1974" - this begs the question of what state the 5000 atoms initially produced in 1950 were in. Is this "unknown", or were they ions detected by the synchrotron? You also say that "nuclei" were produced in 1950, and then later say "atoms". Which was it? Nuclei or atoms?
 * Certainly atoms. Those 5000 atoms were scattered in the target composed of another material (which turned into a complex mixture after irradiation) and were detected by energy and character of emitted particles. I believe those were individual atoms (per low conversion probability) in a solid matrix, and that there was no technique to ascertain that in the 1950s (even now such identification would not be trivial). Materialscientist (talk) 07:03, 6 March 2011 (UTC)
 * Thanks, that makes it clearer. So should the one instance of "nuclei" be changed to "atoms"? Search for "nuclei" in the text of the article. I suppose the equations are for nuclei, aren't they? Though if the beta particle is shown with a minus sign, why is the alpha particle not shown as a double positive charge? Alpha decay has a 2+ by the helium nucleus. I know the electrons matter little here, as these are nuclear reactions, not chemical reactions, but it still seems inconsistent. Carcharoth (talk) 07:55, 6 March 2011 (UTC)
 * The word "nuclei" is not mentioned in the cited source, so removed. --mav (reviews needed) 21:09, 27 March 2011 (UTC)
 * "long-duration irradiation" - what duration? Is this days, months, years? (You do give a hint later, with the "five years" bit).
 * I don't have access to that article, so commented out. --mav (reviews needed) 21:09, 27 March 2011 (UTC)
 * You fail to give the year for the weighable quantities bit.
 * The actual journal article that published the achievement is cited. I don't have access to that article, so I can't say if the achievement was done the same year as publication or before that (or even if the article mentions the date). --mav (reviews needed) 20:42, 6 March 2011 (UTC)
 * I would suggest either trying to get hold of a copy of the reference, or giving the year the results were published. Carcharoth (talk) 03:25, 7 March 2011 (UTC)
 * No access to the cited article, but added when the discovery was reported (likely the same year). --mav (reviews needed) 21:09, 27 March 2011 (UTC)

Occurrence
Please list issues here.

Production

 * "Only two sites produce californium-252" - this repeats what was said in the 'History' section. Readers will notice this. But in any case, the material in each section looks at first glance to be contradictory! The history section says "The High Flux Isotope Reactor (HFIR) at the Savannah River Site in South Carolina" and the rest of the article (including the production section) says "Oak Ridge National Laboratory". When you click on High Flux Isotope Reactor you find out it is "located at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee". But then you go back to the history section of this article, and find that it says "at the Savannah River Site in South Carolina". What is going on here? (Note that the 'Applications' section mentions the 'Savannah River Plant' as well.) The quantities mentioned in the two sections don't seem to match up either. I would say, work out what needs saying, and say it in one section only. Note also my comment on the talk page of this FAC page about the IP edit that seems to have caused the confusion here.
 * Argh - History section cleaned-up. I need to recheck all relevant sources to clear this up in all affected sections. --mav (reviews needed) 03:10, 7 March 2011 (UTC)
 * Struck the above, but did the check get done and was the rest of the article OK? Carcharoth (talk) 22:35, 12 March 2011 (UTC)
 * Yep - looks OK now. --mav (reviews needed) 21:55, 27 March 2011 (UTC)
 * "available for commercial use through the U.S. Nuclear Regulatory Commission" - here, it is worth making clear that the regulatory activities passed to this body (give the year) from the Atomic Energy Commission mentioned in the History section.
 * Ref note added to that effect. --mav (reviews needed) 11:39, 12 March 2011 (UTC)


 * You gave a price in the history section. Are no current prices available?
 * For such elements the price is rarely available in reliable sources, and I can only speculate why (e.g. all orders are highly individual, they specify the required purity, form, etc., that affects the price). Materialscientist (talk) 07:26, 6 March 2011 (UTC)
 * Fair enough. An example here would at least give some idea, but it may be best to let readers look this one up themselves if they are curious. Carcharoth (talk) 03:25, 7 March 2011 (UTC)
 * I spent about an hour searching Google Scholar and Books but could only find refs to the 1970s era price. It is very possible that the price has not changed since but I'm sure there are far more stringent restrictions on obtaining it. --mav (reviews needed) 21:55, 27 March 2011 (UTC)

Applications

 * "half-lifes" - should this be "half-lives"?
 * Yep - fixed. --mav (reviews needed) 22:22, 27 March 2011 (UTC)
 * "received a loan of 119 µg of californium-252" - do you need to link or write out "µg"?
 * Note to Mav: it stood as mg, but changed to µg a few hours ago per source
 * See also my note further down about µg vs mg vs g. Carcharoth (talk) 03:25, 7 March 2011 (UTC)
 * "Neutron penetration into materials makes it useful" - replace "it" with "californium".
 * Done. --mav (reviews needed) 11:50, 12 March 2011 (UTC)
 * As an aside, the 'applications' section is very interesting and well-written, and the changes in use over time was fascinating (the californium bullet bit was hilarious - though not really an 'application' is it?).
 * Thank you. :) The bullet bit is often mentioned as a potential use, and WP:ELEMENTS likes to mention current and potential uses in the Applications section (although outdated uses are normally put in the History section). But yeah, this one is a bit odd since "potential" here is really a stretch; but I couldn't resist mentioning it b/c it is so odd and I couldn't find a better place for it in the History section. --mav (reviews needed) 11:50, 12 March 2011 (UTC)
 * "and fission fragment and half-life studies are other applications of californium" - by "fission fragment" do you mean "fission fragment studies"? I found this sentence a bit impenetrable. It would be nice to know what fission fragment studies are and how californium is used in half-life studies.
 * To clarify: "studies of fission fragments [chemical identity] and half-lives". Technically, these might be different measurements, of emission energy, emitting particle nature, and of decay time. Materialscientist (talk) 07:37, 6 March 2011 (UTC)
 * Indeed and I have no clue either. Commented out until it can be explained better. --mav (reviews needed) 22:22, 27 March 2011 (UTC)
 * There's a two-step reaction, which would do better as two independent ones.--R8R Gtrs (talk) 23:33, 26 March 2011 (UTC)
 * To which reaction are you referring? --mav (reviews needed) 22:22, 27 March 2011 (UTC)
 * (n,γ) → + β− - this one--R8R Gtrs (talk) 17:19, 6 April 2011 (UTC)
 * Is this what you had in mind? I'm not sure the form is correct though. +  →  →  + β− -- mav (reviews needed) 00:14, 7 April 2011 (UTC)
 * + n → + γ
 * → + β−
 * Even though longer, it seems a bit more understandable to me--R8R Gtrs (talk) 15:40, 9 April 2011 (UTC)

Precautions

 * "an initial average concentration of 1 pCi/g" - any chance of explaining what this means? Comparing it to something else? Is this, for example, considered a safe or dangerous level? How does it compare to the levels mentioned in the 'Occurrence' section?
 * Added "For comparison, radiation levels in soil of 0.2 pCi/g are considered low while levels at or above 4.2 pCi/g are regarded as high." As for safety, the same sentence tells exactly the death rate expected from that level of radiation. --mav (reviews needed)

Other

 * Didn't check the infobox (I saw some verification thing going on in all the chemical infoboxes, that I assume has been done now?), though it does look fascinating, but the redlink "d" is a bit distracting. Minor quibble, I know!
 * Minor, but valid. WP template added. I'll verify the data in the table. --mav (reviews needed) 12:40, 12 March 2011 (UTC)
 * In the two equations in the article, I was able to understand what the equations were showing because I can read such equations, but someone with no science background would not recognise them. Is it possible to have links or words under each bit to explain them? In particular, something saying that Cm is curium, that He is (in this case) an alpha particle/helium nucleus, that Cf is californium (in case the reader has forgotten this), and that n is the symbol for a neutron? For the second equation, saying that Bk is Berkelium, that β- is a beta particle/electron, and that n,γ is (I think) neutron and gamma rays?
 * Equation parts parenthetically copied into prose to provide the necessary link/explanation. --mav (reviews needed) 12:40, 12 March 2011 (UTC)

Hopefully some of those comments will be of use. I'll check back over the next few days and see if anything else comes up on a second reading. Carcharoth (talk) 05:47, 6 March 2011 (UTC)
 * The article would read better, IMO, if it ended on the final sentence of the "applications" section. Has the order of sections in the elements articles been determined by WikiProject Chemistry? If so, fair enough, but the "Precautions" section ends on a fairly damp squib of a rather technical nature. Best of all would be to end with the "ununoctium" bit, sticking the "other applications of californium" sentence somewhere else.
 * The section order is set by WP:ELEMENTS. See WikiProject Elements/Guidelines. --mav (reviews needed) 18:33, 6 March 2011 (UTC)
 * Though I see you don't stick rigidly to that layout, so technically this is actionable, or to put it another way, if I pointed out that parts of this article's layout don't conform to that WikiProject guideline (I'm not going to do this, as I agree with the changes you made), you would have to justify the changes, but it doesn't work the other way round? It's not a major concern, but it still stands, as I think ending an article on "precautions" is failing to consider the best way to finish the article. I'll have a look at some other featured articles on elements and consider this some more. Carcharoth (talk) 19:18, 6 March 2011 (UTC)
 * While it is true that we adapt the general guidelines to best fit each element, we are very consistent on placing safety-related info at the bottom of articles. The reasoning is that this info is often of less interest or importance than other info. This follows the news style-like convention of Summary Style, which, admittedly, we don't follow for the Characteristics section b/c we are a bunch of chemistry nerds and think that it is best to start an element article with the most important chemical info before going into the more generally interesting sections on history, occurrence, production and applications (which are in a logical order). I've been tempted for some time to move the suggested location of the Characteristics section to be next to last but my inner nerd rebels against that. --mav (reviews needed) 12:40, 12 March 2011 (UTC)
 * OK, you've convinced me. Carcharoth (talk) 22:34, 12 March 2011 (UTC)
 * Seaborg's Nobel Prize was for his work on discoveries in the transuranic elements. I believe that that includes his work on this element. If that can be double-checked, it is worth mentioning here, I think.
 * Nobel cite says "for their discoveries in the chemistry of the transuranium elements". Cf was announced in Feb. 1950 and the prize given in 1951. The speech mentions Cf, but as a recent addition, thus per my WP:OR I would say it was probably not a decisive element of the Nobel Prize award. Materialscientist (talk) 07:26, 6 March 2011 (UTC)
 * That is the "Presentation Speech by Professor A. Westgren, Chairman of the Nobel Committee for Chemistry of the Royal Swedish Academy of Sciences". Now that you've pointed me there, I got to wondering what Seaborg sent in his Banquet Speech (unfortunately he gave it in Swediah and I can't understand it) or even in his official Nobel Lacture. I tried to find a suitable quote from there, but it doesn't really fit. There might be possibly pointers there to improve the history section still further, though. Carcharoth (talk) 03:25, 7 March 2011 (UTC)
 * The picture of the shipping cask is a great one for this article, but I was hoping to read something in the article about the technology involved there, and what the methods used are to transport this element and why such large and heavy casks are needed. I have a vague idea why, but I'm not going to speculate. The other question would be how the element is got out of that flask and into the equipment mentioned in the applications section.
 * I couldn't find anything useful about transport (likely classified anyway), but I did find some info on why the casts need to be so big. Added. --mav (reviews needed) 01:45, 7 April 2011 (UTC)
 * In some places the article talks about milligrams, in others it talks about micrograms, and in others it talks about grams. This is a difference of several orders of magnitude. I noticed Materialscientist corrected at least one instance where microgram had wrongly been written as milligram. Is it possible to do a complete check through the whole article to make sure no similar mistakes are present? Carcharoth (talk) 03:25, 7 March 2011 (UTC)
 * I looked up all the references that I have access to in order to confirm each instance of gram/mg/microgram. --mav (reviews needed) 00:32, 8 April 2011 (UTC)
 * Thank you for the review - I'll start addressing your points later on Sunday. --mav (reviews needed) 06:36, 6 March 2011 (UTC)


 * Comments - reading through now - will make straightforward copyedits as I go (please revert if I inadvertently change the meaning), and jot queries below: Casliber (talk · contribs) 07:11, 11 March 2011 (UTC)


 * In the Physical properties section, you change from Celsius to Kelvin. I think it'd be better to stick to one or used C (K) or something.
 * Asked and answered in the FAC; Kelvin is the appropriate unit for extreme temperatures while Celsius is the appropriate unit for normal temperatures. But I added a couple Celsius conversions in strategic locations to give perspective. --mav (reviews needed) 01:58, 7 April 2011 (UTC)

Above text copied from archived FAC page with addressed and struck items removed. If I deleted any comments that were not completely addressed, then please re-add them. Please also add any other comments on things that need to be improved before re-submittal to FAC. --mav (reviews needed) 11:15, 12 March 2011 (UTC)
 * See also the neutron cross-section talk page section above. Carcharoth (talk) 22:36, 12 March 2011 (UTC)


 * I've nominated it for GA first to see where we are at. Lanthanum-138 (talk) 08:14, 13 April 2011 (UTC)
 * Please ask on talk page before nominating articles you are not a significant contributor to. The fact that there is a GAN is delaying a second FAC. --mav (reviews needed) 16:51, 16 April 2011 (UTC)
 * Sorry. I just felt that it kind of made sense. Anyway, the GAN's over. Lanthanum-138 (talk) 13:47, 26 April 2011 (UTC)