Californium: Difference between revisions
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{{About|the chemical element}} | {{About|the chemical element|the video game|Californium (video game) {{!}}''Californium '' (video game)}} | ||
{{use mdy dates|date=March 2018}} | {{use mdy dates|date=March 2018}} | ||
{{featured article}} | {{featured article}} | ||
{{infobox californium}} | {{infobox californium}} | ||
'''Californium''' is a [[synthetic element|synthetic chemical element]]; it has [[Chemical symbol|symbol]] '''Cf''' and [[atomic number]] 98. It was first synthesized in 1950 at [[Lawrence Berkeley National Laboratory]] (then the University of California Radiation Laboratory) by bombarding [[curium]] with [[alpha particle]]s ([[helium-4]] ions). It is an [[actinide]] element, the sixth [[transuranium element]] to be [[synthetic element|synthesized]], and has the second-highest atomic mass of all elements that have been produced in amounts large enough to see with the [[naked eye]] (after [[einsteinium]]). It was named after the university and the [[U.S. state]] of [[California]]. | '''Californium''' is a [[synthetic element|synthetic chemical element]]; it has [[Chemical symbol|symbol]] '''Cf''' and [[atomic number]] 98. It was first synthesized in 1950 at [[Lawrence Berkeley National Laboratory]] (then the University of California Radiation Laboratory) by bombarding [[curium]] with [[alpha particle]]s ([[helium-4]] ions). It is an [[actinide]] element, the sixth [[transuranium element]] to be [[synthetic element|synthesized]], and has the second-highest atomic mass of all elements that have been produced in amounts large enough to see with the [[naked eye]] (after [[einsteinium]]). It was named after the [[University of California, Berkeley|university]] and the [[U.S. state]] of [[California]]. | ||
Two [[crystal structure|crystalline forms]] exist at normal pressure: one above and one below {{convert|900|C|-1}}. A third form exists at high pressure. Californium slowly tarnishes in air at room temperature. [[Californium compounds]] are dominated by the +3 [[oxidation state]]. The most stable of californium's twenty known [[isotope]]s is californium-251, with a [[half-life]] of 898 years. This short half-life means the element is not found in significant quantities in the Earth's crust.{{efn|name=age of earth}} {{sup|252}}Cf, with a half-life of about 2.645 years, is the most common isotope used and is produced at [[Oak Ridge National Laboratory]] (ORNL) in the United States and [[Research Institute of Atomic Reactors]] in Russia. | Two [[crystal structure|crystalline forms]] exist at normal pressure: one above and one below {{convert|900|C|-1}}. A third form exists at high pressure. Californium slowly tarnishes in air at room temperature. [[Californium compounds]] are dominated by the +3 [[oxidation state]]. The most stable of californium's twenty known [[isotope]]s is californium-251, with a [[half-life]] of 898 years. This short half-life means the element is not found in significant quantities in the Earth's crust.{{efn|name=age of earth}} {{sup|252}}Cf, with a half-life of about 2.645 years, is the most common isotope used and is produced at [[Oak Ridge National Laboratory]] (ORNL) in the United States and [[Research Institute of Atomic Reactors]] in Russia. | ||
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=== Isotopes === | === Isotopes === | ||
{{main|Isotopes of californium}} | {{main|Isotopes of californium}} | ||
Twenty [[isotope]]s of californium are known | :''All nuclear data not otherwise stated is from the standard source:<ref>{{NUBASE2020}}</ref>'' | ||
Twenty [[isotope]]s of californium are known with [[mass number]] ranging from 237 to 256; the most stable are {{sup|251}}Cf with [[half-life]] 898 years, {{sup|249}}Cf with half-life 351 years, {{sup|250}}Cf at 13.08 years, and {{sup|252}}Cf at 2.645 years. All other isotopes have half-life shorter than a year, and most of these have half-lives less than 20 minutes. | |||
{{sup|249}}Cf is formed by [[beta decay]] of berkelium-249, and | {{sup|249}}Cf is formed by [[beta decay]] of berkelium-249, and heavier californium isotopes are made by subjecting berkelium to intense neutron radiation in a [[nuclear reactor]]. Though californium-251 has the longest half-life, its production yield is relatively low due to its rapid depletion by reaction with another neutron (high [[neutron cross section]]).{{sfn|Haire|2006|p=1504}} | ||
{{sup|252}}Cf is a very strong [[neutron]] emitter, which makes it extremely [[radioactive]] | {{sup|252}}Cf is a very strong [[neutron]] emitter, which makes it an extremely hazardous [[radioactive]] isotope.<ref>{{cite journal|author = Hicks, D. A. |title = Multiplicity of Neutrons from the Spontaneous Fission of Californium-252|journal = Physical Review|date = 1955|volume = 97|issue = 2|pages = 564–565|doi = 10.1103/PhysRev.97.564|last2 = Ise|first2 = John|last3 = Pyle|first3 = Robert V.|bibcode = 1955PhRv...97..564H |url = http://www.escholarship.org/uc/item/6031k6m2}}</ref><ref>{{cite journal|author = Hicks, D. A. |title = Spontaneous-Fission Neutrons of Californium-252 and Curium-244|journal = Physical Review |date = 1955|volume = 98|issue = 5|pages = 1521–1523|doi = 10.1103/PhysRev.98.1521|last2 = Ise|first2 = John|last3 = Pyle|first3 = Robert V.|bibcode = 1955PhRv...98.1521H }}</ref><ref>{{cite journal|author =Hjalmar, E.|author2 =Slätis, H.|author3 =Thompson, S.G. |title = Energy Spectrum of Neutrons from Spontaneous Fission of Californium-252| journal = Physical Review| date = 1955| volume = 100|issue =5|pages = 1542–1543| doi = 10.1103/PhysRev.100.1542|bibcode = 1955PhRv..100.1542H }}</ref> {{sup|252}}Cf, 96.9% of the time, [[alpha decay]]s to [[curium]]-248; the other 3.1% of decays are [[spontaneous fission]]. One [[microgram]] of {{sup|252}}Cf emits 2.3 million neutrons per second (about 3.7 neutrons per fission).<ref name="osti">{{cite journal|author = Martin, R. C.|author2 = Knauer, J. B.|author3 = Balo, P. A.| title = Production, Distribution, and Applications of Californium-252 Neutron Sources| date = 1999|url = http://www.osti.gov/bridge/purl.cover.jsp?purl=/15053-AE6cnN/native/ |doi = 10.1016/S0969-8043(00)00214-1|journal = Applied Radiation and Isotopes |volume = 53|issue = 4–5|pages = 785–92|pmid = 11003521 | osti=15053 }}</ref> The other main isotopes of californium (248-251) also alpha decay to those of [[curium]], with a much smaller fraction of fission. | ||
== History == | == History == | ||
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Californium was [[timeline of chemical element discoveries|first made]] at [[University of California, Berkeley|University of California]] [[Lawrence Berkeley National Laboratory|Radiation Laboratory]], [[Berkeley, California|Berkeley]], by physics researchers [[Stanley Gerald Thompson]], [[Kenneth Street Jr.]], [[Albert Ghiorso]], and [[Glenn T. Seaborg]], about February 9, 1950.{{sfn|Cunningham|1968|p=103}} It was the sixth [[transuranium element]] to be discovered; the team announced its discovery on March 17, 1950.<ref name="CPoC1950">{{cite journal |last1 = Street | first1 = K. Jr. |last2 = Thompson |first2 = S. G. |last3 = Seaborg |first3 = Glenn T. |title = Chemical Properties of Californium |journal = Journal of the American Chemical Society |date = 1950 |volume = 72 |issue = 10 |page = 4832 |doi = 10.1021/ja01166a528 | bibcode = 1950JAChS..72R4832S |url = https://apps.dtic.mil/sti/pdfs/ADA319899.pdf |hdl = 2027/mdp.39015086449173 |access-date = February 20, 2011 |archive-date = January 19, 2012 |archive-url = https://web.archive.org/web/20120119092943/http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA319899&Location=U2&doc=GetTRDoc.pdf |url-status = live }}</ref><ref>{{cite book |author=Glenn Theodore Seaborg |author-link=Glenn T. Seaborg bibliography |title=Journal of Glenn T. Seaborg, 1946–1958: January 1, 1950{{snd}} December 31, 1950 |url=https://books.google.com/books?id=pvpDAQAAIAAJ |year=1990 |publisher=Lawrence Berkeley Laboratory, University of California |page=80}}</ref> | Californium was [[timeline of chemical element discoveries|first made]] at [[University of California, Berkeley|University of California]] [[Lawrence Berkeley National Laboratory|Radiation Laboratory]], [[Berkeley, California|Berkeley]], by physics researchers [[Stanley Gerald Thompson]], [[Kenneth Street Jr.]], [[Albert Ghiorso]], and [[Glenn T. Seaborg]], about February 9, 1950.{{sfn|Cunningham|1968|p=103}} It was the sixth [[transuranium element]] to be discovered; the team announced its discovery on March 17, 1950.<ref name="CPoC1950">{{cite journal |last1 = Street | first1 = K. Jr. |last2 = Thompson |first2 = S. G. |last3 = Seaborg |first3 = Glenn T. |title = Chemical Properties of Californium |journal = Journal of the American Chemical Society |date = 1950 |volume = 72 |issue = 10 |page = 4832 |doi = 10.1021/ja01166a528 | bibcode = 1950JAChS..72R4832S |url = https://apps.dtic.mil/sti/pdfs/ADA319899.pdf |hdl = 2027/mdp.39015086449173 |access-date = February 20, 2011 |archive-date = January 19, 2012 |archive-url = https://web.archive.org/web/20120119092943/http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA319899&Location=U2&doc=GetTRDoc.pdf |url-status = live }}</ref><ref>{{cite book |author=Glenn Theodore Seaborg |author-link=Glenn T. Seaborg bibliography |title=Journal of Glenn T. Seaborg, 1946–1958: January 1, 1950{{snd}} December 31, 1950 |url=https://books.google.com/books?id=pvpDAQAAIAAJ |year=1990 |publisher=Lawrence Berkeley Laboratory, University of California |page=80}}</ref> | ||
To produce californium, a microgram-size target of curium-242 ( | To produce californium, a microgram-size target of curium-242 (<sup>242</sup>Cm) was bombarded with 35 MeV [[alpha particle]]s (<sup>4</sup>He) in the {{convert|60|in|m|2|adj=mid|-diameter}} [[cyclotron]] at Berkeley, which produced californium-245 (<sup>245</sup>Cf) plus one [[free neutron]] ({{SubatomicParticle|neutron}}).{{sfn|Cunningham|1968|p=103}}<ref name="CPoC1950" /> | ||
<!-- Weeks & Leichester 1968 p. 849 gives product as 98-244 --> | <!-- Weeks & Leichester 1968 p. 849 gives product as 98-244 --> | ||
: {{nuclide|curium|242}} + {{nuclide|helium|4}} → {{nuclide|californium|245}} + {{ | : {{nuclide|curium|242}} + {{nuclide|helium|4}} → {{nuclide|californium|245}} + {{Nuclide|neutronium|1}} | ||
To identify and separate out the element, [[ion exchange]] and adsorsion methods were undertaken.<ref name="CPoC1950" /><ref>{{cite journal |last1=Thompson |first1=S. G. | last2=Street | first2=K. Jr. |first3=Ghiorso |last3=A. |last4=Seaborg |first4=Glenn T.|title = Element 98 |journal = Physical Review |date=1950 |volume = 78 |issue = 3 |page = 298 |doi = 10.1103/PhysRev.78.298.2 |url=http://escholarship.org/uc/item/44g7z6hk |bibcode = 1950PhRv...78..298T|doi-access=free }}</ref> Only about 5,000 atoms of californium were produced in this experiment,{{sfn|Seaborg|1996|p=82}} and these atoms had a half-life of 44 minutes.{{sfn|Cunningham|1968|p=103}} | To identify and separate out the element, [[ion exchange]] and adsorsion methods were undertaken.<ref name="CPoC1950" /><ref>{{cite journal |last1=Thompson |first1=S. G. | last2=Street | first2=K. Jr. |first3=Ghiorso |last3=A. |last4=Seaborg |first4=Glenn T.|title = Element 98 |journal = Physical Review |date=1950 |volume = 78 |issue = 3 |page = 298 |doi = 10.1103/PhysRev.78.298.2 |url=http://escholarship.org/uc/item/44g7z6hk |bibcode = 1950PhRv...78..298T|doi-access=free }}</ref> Only about 5,000 atoms of californium were produced in this experiment,{{sfn|Seaborg|1996|p=82}} and these atoms had a half-life of 44 minutes.{{sfn|Cunningham|1968|p=103}} | ||
The discoverers named the new element after the university and the state. This was a break from the convention used for elements 95 to 97, which drew inspiration from how the elements directly above them in the periodic table were named.{{sfn|Weeks|Leichester|1968|p=849}}{{efn|[[Europium]], in the sixth period directly above element 95, was named for the continent it was discovered on, so element 95 was named [[americium]]. Element 96 was named [[curium]] for [[Marie Curie]] and [[Pierre Curie]] as an analog to the naming of [[gadolinium]], which was named for the scientist and engineer [[Johan Gadolin]]. [[Terbium]] was named for the village it was discovered in, so element 97 was named [[berkelium]].{{sfn|Weeks|Leichester|1968|p=848}} }} However, the element directly above element 98 in the periodic table, [[dysprosium]], has a name that means "hard to get at", so the researchers decided to set aside the informal naming convention.{{sfn|Heiserman|1992|p=347}} They added that "the best we can do is to point out [that] ... searchers a century ago found it difficult to get to California".{{sfn|Weeks|Leichester|1968|p=848}} | The discoverers named the new element after the university and the state. This was a break from the convention used for elements 95 to 97, which drew inspiration from how the elements directly above them in the periodic table were named.{{sfn|Weeks|Leichester|1968|p=849}}{{efn|[[Europium]], in the sixth period directly above element 95, was named for the continent it was discovered on, so element 95 was named [[americium]]. Element 96 was named [[curium]] for [[Marie Curie]] and [[Pierre Curie]] as an analog to the naming of [[gadolinium]], which was named for the scientist and engineer [[Johan Gadolin]]. [[Terbium]] was named for the village it was discovered in, so element 97 was named [[berkelium]].{{sfn|Weeks|Leichester|1968|p=848}} }} However, the element directly above element 98 in the periodic table, [[dysprosium]], has a name that means "hard to get at", so the researchers decided to set aside the informal naming convention.{{sfn|Heiserman|1992|p=347}} They added that "the best we can do is to point out [that] ... searchers a century ago found it difficult to get to California".{{sfn|Weeks|Leichester|1968|p=848}} | ||
Weighable amounts of californium were first produced by the<!-- long duration -HOW LONG? --> irradiation of plutonium targets at [[Materials Testing Reactor]] at [[Idaho National Laboratory|National Reactor Testing Station]], [[eastern Idaho]]; these findings were reported in 1954.<ref>{{cite journal |journal=[[Physical Review]] |volume=94 |issue=4 | | Weighable amounts of californium were first produced by the<!-- long duration -HOW LONG? --> irradiation of plutonium targets at [[Materials Testing Reactor]] at [[Idaho National Laboratory|National Reactor Testing Station]], [[eastern Idaho]]; these findings were reported in 1954.<ref>{{cite journal |journal=[[Physical Review]] |volume=94 |issue=4 |page=1083 |date=1954 |author=Diamond, H. |title=Identification of Californium Isotopes 249, 250, 251, and 252 from Pile-Irradiated Plutonium |doi = 10.1103/PhysRev.94.1083 |bibcode = 1954PhRv...94.1083D |last2=Magnusson |first2=L. |last3=Mech |first3=J. |last4=Stevens |first4=C. |last5=Friedman |first5=A. |last6=Studier |first6=M. |last7=Fields |first7=P. |last8=Huizenga |first8=J. }}</ref> The high spontaneous fission rate of californium-252 was observed in these samples. The first experiment with californium in concentrated form occurred in 1958.{{sfn|Cunningham|1968|p=103}} The isotopes {{sup|249}}Cf to {{sup|252}}Cf were isolated that same year from a sample of [[plutonium-239]] that had been irradiated with neutrons in a nuclear reactor for five years.{{sfn|Jakubke|1994|p=166}} Two years later, in 1960, Burris Cunningham and James Wallman of Lawrence Radiation Laboratory of the University of California created the first californium compounds—californium trichloride, [[californium(III) oxychloride]], and californium oxide—by treating californium with steam and [[hydrochloric acid]].<ref>{{cite journal |journal = Science News Letter |volume = 78 |issue = 26 |date=December 1960 |title = Element 98 Prepared }}</ref> | ||
The [[High Flux Isotope Reactor]] (HFIR) at ORNL in [[Oak Ridge, Tennessee]], started producing small batches of californium in the 1960s.<ref>{{cite web |url=http://web.ornl.gov/sci/rrd/pages/hfir.html |title=The High Flux Isotope Reactor |publisher=Oak Ridge National Laboratory |access-date=August 22, 2010 |archive-url=https://web.archive.org/web/20100527164346/http://web.ornl.gov/sci/rrd/pages/hfir.html <!--Added by H3llBot--> |archive-date=May 27, 2010 }}</ref> By 1995, HFIR nominally produced {{convert|500|mg|oz}} of californium annually.{{sfn|Osborne-Lee|1995|p=11}} Plutonium supplied by the United Kingdom to the United States under the [[1958 US–UK Mutual Defence Agreement]] was used for making californium.<ref>{{cite web |archive-url=https://web.archive.org/web/20061213032416/http://www.mod.uk/NR/rdonlyres/B31B4EF0-A584-4CC6-9B14-B5E89E6848F8/0/plutoniumandaldermaston.pdf |archive-date=December 13, 2006 |url=http://www.mod.uk/NR/rdonlyres/B31B4EF0-A584-4CC6-9B14-B5E89E6848F8/0/plutoniumandaldermaston.pdf |title=Plutonium and Aldermaston – an Historical Account |publisher=UK Ministry of Defence |date=September 4, 2001 |access-date=March 15, 2007|page=30 }}</ref> | The [[High Flux Isotope Reactor]] (HFIR) at ORNL in [[Oak Ridge, Tennessee]], started producing small batches of californium in the 1960s.<ref>{{cite web |url=http://web.ornl.gov/sci/rrd/pages/hfir.html |title=The High Flux Isotope Reactor |publisher=Oak Ridge National Laboratory |access-date=August 22, 2010 |archive-url=https://web.archive.org/web/20100527164346/http://web.ornl.gov/sci/rrd/pages/hfir.html <!--Added by H3llBot--> |archive-date=May 27, 2010 }}</ref> By 1995, HFIR nominally produced {{convert|500|mg|oz}} of californium annually.{{sfn|Osborne-Lee|1995|p=11}} Plutonium supplied by the United Kingdom to the United States under the [[1958 US–UK Mutual Defence Agreement]] was used for making californium.<ref>{{cite web |archive-url=https://web.archive.org/web/20061213032416/http://www.mod.uk/NR/rdonlyres/B31B4EF0-A584-4CC6-9B14-B5E89E6848F8/0/plutoniumandaldermaston.pdf |archive-date=December 13, 2006 |url=http://www.mod.uk/NR/rdonlyres/B31B4EF0-A584-4CC6-9B14-B5E89E6848F8/0/plutoniumandaldermaston.pdf |title=Plutonium and Aldermaston – an Historical Account |publisher=UK Ministry of Defence |date=September 4, 2001 |access-date=March 15, 2007|page=30 }}</ref> | ||
The [[United States Atomic Energy Commission|Atomic Energy Commission]] sold {{sup|252}}Cf to industrial and academic customers in the early 1970s for $10/microgram,<ref name="osti" /> and an average of {{convert|150|mg|oz|abbr=on}} of {{sup|252}}Cf were shipped each year from 1970 to 1990.{{sfn|Osborne-Lee|1995|p=6}}{{efn|The [[Nuclear Regulatory Commission]] replaced the Atomic Energy Commission when the [[Energy Reorganization Act of 1974]] was implemented. The price of californium-252 was increased by the NRC several times and was $60 per microgram by 1999; this price does not include the cost of encapsulation and transportation.<ref name="osti" /> }} Californium metal was first prepared in 1974 by Haire and Baybarz, who reduced californium(III) oxide with lanthanum metal to obtain microgram amounts of sub-micrometer thick films.{{sfn|Haire|2006|p=1519}}<ref>{{cite journal |last1=Haire |first1=R. G. |last2=Baybarz |first2=R. D. |title=Crystal Structure and Melting Point of Californium Metal |journal=Journal of Inorganic and Nuclear Chemistry |volume=36 |issue=6 | | The [[United States Atomic Energy Commission|Atomic Energy Commission]] sold {{sup|252}}Cf to industrial and academic customers in the early 1970s for $10/microgram,<ref name="osti" /> and an average of {{convert|150|mg|oz|abbr=on}} of {{sup|252}}Cf were shipped each year from 1970 to 1990.{{sfn|Osborne-Lee|1995|p=6}}{{efn|The [[Nuclear Regulatory Commission]] replaced the Atomic Energy Commission when the [[Energy Reorganization Act of 1974]] was implemented. The price of californium-252 was increased by the NRC several times and was $60 per microgram by 1999; this price does not include the cost of encapsulation and transportation.<ref name="osti" /> }} Californium metal was first prepared in 1974 by Haire and Baybarz, who reduced californium(III) oxide with lanthanum metal to obtain microgram amounts of sub-micrometer thick films.{{sfn|Haire|2006|p=1519}}<ref>{{cite journal |last1=Haire |first1=R. G. |last2=Baybarz |first2=R. D. |title=Crystal Structure and Melting Point of Californium Metal |journal=Journal of Inorganic and Nuclear Chemistry |volume=36 |issue=6 |page=1295 |date=1974 |doi=10.1016/0022-1902(74)80067-9 }}</ref>{{efn|In 1975, another paper stated that the californium metal prepared the year before was the hexagonal compound Cf{{sub|2}}O{{sub|2}}S and face-centered cubic compound CfS.<ref>{{cite journal |doi=10.1016/0022-1902(75)80787-1 |journal=Journal of Inorganic and Nuclear Chemistry |date=1975 |pages=1441–1442 |volume=37 |issue=6 |title=On Californium Metal |last=Zachariasen |first=W. }}</ref> The 1974 work was confirmed in 1976 and work on californium metal continued.{{sfn|Haire|2006|p=1519}} }} | ||
== Occurrence == | == Occurrence == | ||
Traces of californium can be found near facilities that use the element in mineral prospecting and in medical treatments.{{sfn|Emsley|2001|p=90}} The element is fairly insoluble in water, but it adheres well to ordinary soil; and concentrations of it in the soil can be 500 times higher than in the water surrounding the soil particles.<ref name="ANL2005">{{cite web|url=http://www.evs.anl.gov/pub/doc/Californium.pdf |title=Human Health Fact Sheet: Californium |date=August 2005 |publisher=Argonne National Laboratory | Traces of californium can be found near facilities that use the element in mineral prospecting and in medical treatments.{{sfn|Emsley|2001|p=90}} The element is fairly insoluble in water, but it adheres well to ordinary soil; and concentrations of it in the soil can be 500 times higher than in the water surrounding the soil particles.<ref name="ANL2005">{{cite web|url=http://www.evs.anl.gov/pub/doc/Californium.pdf |title=Human Health Fact Sheet: Californium |date=August 2005 |publisher=Argonne National Laboratory |archive-url=https://web.archive.org/web/20110721032736/http://www.evs.anl.gov/pub/doc/Californium.pdf |archive-date=July 21, 2011 }}</ref> | ||
[[Nuclear fallout]] from atmospheric [[nuclear weapons testing]] prior to 1980 contributed a small amount of californium to the environment.<ref name="ANL2005" /> Californium-249, -252, -253, and -254 have been observed in the radioactive dust collected from the air after a nuclear explosion.<ref>{{cite journal|title = Transplutonium Elements in Thermonuclear Test Debris|journal = Physical Review|date = 1956|volume = 102|issue = 1|pages = 180–182|doi = 10.1103/PhysRev.102.180|bibcode = 1956PhRv..102..180F|last1=Fields|first1=P. R.|last2 = Studier|first2 = M.|last3 = Diamond|first3 = H.|last4 = Mech|first4 = J.|last5 = Inghram|first5 = M.|last6 = Pyle|first6 = G.|last7 = Stevens|first7 = C.|last8 = Fried|first8 = S.|last9 = Manning|first9 = W.|display-authors=8}}</ref> Californium is not a major radionuclide at [[United States Department of Energy]] legacy sites since it was not produced in large quantities.<ref name="ANL2005" /> | [[Nuclear fallout]] from atmospheric [[nuclear weapons testing]] prior to 1980 contributed a small amount of californium to the environment.<ref name="ANL2005" /> Californium-249, -252, -253, and -254 have been observed in the radioactive dust collected from the air after a nuclear explosion.<ref>{{cite journal|title = Transplutonium Elements in Thermonuclear Test Debris|journal = Physical Review|date = 1956|volume = 102|issue = 1|pages = 180–182|doi = 10.1103/PhysRev.102.180|bibcode = 1956PhRv..102..180F|last1=Fields|first1=P. R.|last2 = Studier|first2 = M.|last3 = Diamond|first3 = H.|last4 = Mech|first4 = J.|last5 = Inghram|first5 = M.|last6 = Pyle|first6 = G.|last7 = Stevens|first7 = C.|last8 = Fried|first8 = S.|last9 = Manning|first9 = W.|display-authors=8}}</ref> Californium is not a major radionuclide at [[United States Department of Energy]] legacy sites since it was not produced in large quantities.<ref name="ANL2005" /> | ||
Californium was once believed to be produced in [[supernova]]s, as their decay matches the 60-day half-life of {{sup|254}}Cf.<ref name="super1">{{cite journal|last=Baade|first=W.|author2=Burbidge, G. R.|author3=Hoyle, F.|author4=Burbidge, E. M.|author5=Christy, R. F.|author6=Fowler, W. A.|title=Supernovae and Californium 254|journal=Publications of the Astronomical Society of the Pacific|date=August 1956|volume=68|issue=403|pages=296–300|doi=10.1086/126941|url=http://authors.library.caltech.edu/6553/1/BURpr56.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://authors.library.caltech.edu/6553/1/BURpr56.pdf |archive-date=2022-10-10 |url-status=live|access-date=September 26, 2012|bibcode = 1956PASP...68..296B |doi-access=free}}</ref> However, subsequent studies failed to demonstrate any californium spectra,<ref name="super2">{{cite journal|last=Conway|first=J. G.|author2=Hulet, E.K. |author3=Morrow, R.J. |title=Emission Spectrum of Californium|journal=Journal of the Optical Society of America|date=February 1, 1962|volume=52|issue=2| | Californium was once believed to be produced in [[supernova]]s, as their decay matches the 60-day half-life of {{sup|254}}Cf.<ref name="super1">{{cite journal|last=Baade|first=W.|author2=Burbidge, G. R.|author3=Hoyle, F.|author4=Burbidge, E. M.|author5=Christy, R. F.|author6=Fowler, W. A.|title=Supernovae and Californium 254|journal=Publications of the Astronomical Society of the Pacific|date=August 1956|volume=68|issue=403|pages=296–300|doi=10.1086/126941|url=http://authors.library.caltech.edu/6553/1/BURpr56.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://authors.library.caltech.edu/6553/1/BURpr56.pdf |archive-date=2022-10-10 |url-status=live|access-date=September 26, 2012|bibcode = 1956PASP...68..296B |doi-access=free}}</ref> However, subsequent studies failed to demonstrate any californium spectra,<ref name="super2">{{cite journal|last=Conway|first=J. G.|author2=Hulet, E.K. |author3=Morrow, R.J. |title=Emission Spectrum of Californium|journal=Journal of the Optical Society of America|date=February 1, 1962|volume=52|issue=2|page=222|doi=10.1364/josa.52.000222 |pmid=13881026|bibcode=1962JOSA...52..222C |osti=4806792|url=http://www.escholarship.org/uc/item/9c3297wf}}</ref> and supernova light curves are now thought to follow the decay of [[Isotopes of nickel|nickel-56]].{{sfn|Ruiz-Lapuente1996|p=274}} | ||
The transuranic elements up to [[fermium]], including californium, should have been present in the [[natural nuclear fission reactor]] at [[Oklo]], but any quantities produced then would have long since decayed away.<ref name="emsley">{{cite book|last=Emsley|first=John|title=Nature's Building Blocks: An A-Z Guide to the Elements|edition=New|date=2011|publisher=Oxford University Press|location=New York, NY|isbn=978-0-19-960563-7}}</ref> | The transuranic elements up to [[fermium]], including californium, should have been present in the [[natural nuclear fission reactor]] at [[Oklo]], but any quantities produced then would have long since decayed away.<ref name="emsley">{{cite book|last=Emsley|first=John|title=Nature's Building Blocks: An A-Z Guide to the Elements|edition=New|date=2011|publisher=Oxford University Press|location=New York, NY|isbn=978-0-19-960563-7}}</ref> | ||
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== Applications == | == Applications == | ||
[[File:CfShield.JPG|thumb|Fifty-ton shipping cask built at ORNL which can transport up to 1 gram of {{sup|252}}Cf.{{sfn|Seaborg|1994|p=245}} Large and heavily shielded transport containers are needed to prevent the release of highly radioactive material in case of normal and hypothetical accidents.<ref>{{cite web|url=http://rampac.energy.gov/PCN/EM-PCP-certified-pkgs-8808.pdf|title=DOE Certified Radioactive Materials Transportation Packagings|last=Shuler|first=James|date=2008|page=1|publisher=United States Department of Energy|access-date=April 7, 2011|archive-date=October 15, 2011|archive-url=https://web.archive.org/web/20111015040627/http://rampac.energy.gov/PCN/EM-PCP-certified-pkgs-8808.pdf | [[File:CfShield.JPG|thumb|Fifty-ton shipping cask built at ORNL which can transport up to 1 gram of {{sup|252}}Cf.{{sfn|Seaborg|1994|p=245}} Large and heavily shielded transport containers are needed to prevent the release of highly radioactive material in case of normal and hypothetical accidents.<ref>{{cite web|url=http://rampac.energy.gov/PCN/EM-PCP-certified-pkgs-8808.pdf|title=DOE Certified Radioactive Materials Transportation Packagings|last=Shuler|first=James|date=2008|page=1|publisher=United States Department of Energy|access-date=April 7, 2011|archive-date=October 15, 2011|archive-url=https://web.archive.org/web/20111015040627/http://rampac.energy.gov/PCN/EM-PCP-certified-pkgs-8808.pdf}}</ref>|alt= Large conical structure on a pulley with a man on top and two near the base.]] | ||
<!-- NEEDS CITE Californium is the heaviest metal known at this time that has a practical use outside of research laboratories; [[einsteinium]] and all other elements above it have sufficiently short half-lives that they have no use except the production of heavier elements.-->=== Neutron source === | <!-- NEEDS CITE Californium is the heaviest metal known at this time that has a practical use outside of research laboratories; [[einsteinium]] and all other elements above it have sufficiently short half-lives that they have no use except the production of heavier elements.-->=== Neutron source === | ||
{{SimpleNuclide|Californium|252|link=yes}} has a number of specialized uses as a strong [[Neutron source|neutron emitter]]; it produces 139 million neutrons per microgram per minute.<ref name="osti" /> This property makes it useful as a [[startup neutron source]] for some nuclear reactors{{sfn|O'Neil|2006|p=276}} and as a portable (non-reactor based) neutron source for [[neutron activation analysis]] to detect trace amounts of elements in samples.<ref name="Martin2000">{{cite conference|last=Martin |first=R. C. |title=Applications and Availability of Californium-252 Neutron Sources for Waste Characterization |date=September 24, 2000 |url=http://www.ornl.gov/~webworks/cpr/pres/107270_.pdf |access-date=May 2, 2010 |conference=Spectrum 2000 International Conference on Nuclear and Hazardous Waste Management |location=Chattanooga, Tennessee | {{SimpleNuclide|Californium|252|link=yes}} has a number of specialized uses as a strong [[Neutron source|neutron emitter]]; it produces 139 million neutrons per microgram per minute.<ref name="osti" /> This property makes it useful as a [[startup neutron source]] for some nuclear reactors{{sfn|O'Neil|2006|p=276}} and as a portable (non-reactor based) neutron source for [[neutron activation analysis]] to detect trace amounts of elements in samples.<ref name="Martin2000">{{cite conference|last=Martin |first=R. C. |title=Applications and Availability of Californium-252 Neutron Sources for Waste Characterization |date=September 24, 2000 |url=http://www.ornl.gov/~webworks/cpr/pres/107270_.pdf |access-date=May 2, 2010 |conference=Spectrum 2000 International Conference on Nuclear and Hazardous Waste Management |location=Chattanooga, Tennessee |archive-url=https://web.archive.org/web/20100601160926/http://www.ornl.gov/~webworks/cpr/pres/107270_.pdf |archive-date=June 1, 2010 }}</ref>{{efn|By 1990, californium-252 had replaced plutonium-[[beryllium]] neutron sources due to its smaller size and lower heat and gas generation.{{sfn|Seaborg|1990|p=318}} }} Neutrons from californium are used as a treatment of certain [[Cervical cancer|cervical]] and [[brain tumor|brain cancers]] where other [[radiation therapy]] is ineffective.{{sfn|O'Neil|2006|p=276}} It has been used in educational applications since 1969 when [[Georgia Tech|Georgia Institute of Technology]] got a loan of 119 μg of {{sup|252}}Cf from the [[Savannah River Site]].{{sfn|Osborne-Lee|1995|p=33}} It is also used with online elemental [[coal analyzer]]s and [[bulk material analyzer]]s in the coal and cement industries. | ||
Neutron penetration into materials makes californium useful in detection instruments such as [[fuel rod]] scanners;{{sfn|O'Neil|2006|p=276}} [[Neutron imaging#Neutron radiography (film)|neutron radiography]] of aircraft and weapons components to detect [[corrosion]], bad welds, cracks and trapped moisture;{{sfn|Osborne-Lee|1995|pp=26–27}}<!-- NEEDS CITE in airport [[prompt gamma neutron activation analysis|neutron-activation]] detectors of explosives, --> and in portable metal detectors.<ref>{{cite web|url=http://www.pnl.gov/news/2000/00-43.htm|title=Will You be 'Mine'? Physics Key to Detection|date=October 25, 2000|publisher = Pacific Northwest National Laboratory|access-date = March 21, 2007 |archive-url = https://web.archive.org/web/20070218125029/http://www.pnl.gov/news/2000/00-43.htm <!-- Bot retrieved archive --> |archive-date = February 18, 2007 }}</ref> [[Neutron moisture gauge]]s use {{sup|252}}Cf to find water and petroleum layers in oil wells, as a portable [[neutron source]] for gold and silver prospecting for on-the-spot analysis,{{sfn|CRC|2006|p=4.8}} and to detect ground water movement.<ref>{{cite journal|journal = Ground Water|volume = 18|issue = 1|pages =14–23|date = 2006|title =Ground-Water Tracers – A Short Review|author = Davis, S. N. |doi = 10.1111/j.1745-6584.1980.tb03366.x|last2 = Thompson|first2 = Glenn M.|last3 = Bentley|first3 = Harold W.|last4 = Stiles|first4 = Gary }}</ref> The main uses of {{sup|252}}Cf in 1982 were, reactor start-up (48.3%), fuel rod scanning (25.3%), and activation analysis (19.4%).{{sfn|Osborne-Lee|1995|p=12}} By 1994, most {{sup|252}}Cf was used in neutron radiography (77.4%), with fuel rod scanning (12.1%) and reactor start-up (6.9%) as important but secondary uses.{{sfn|Osborne-Lee|1995|p=12}} In 2021, fast neutrons from {{sup|252}}Cf were used for wireless data transmission.<ref>{{cite journal|journal = Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment|volume = 1021|issue = 1| | Neutron penetration into materials makes californium useful in detection instruments such as [[fuel rod]] scanners;{{sfn|O'Neil|2006|p=276}} [[Neutron imaging#Neutron radiography (film)|neutron radiography]] of aircraft and weapons components to detect [[corrosion]], bad welds, cracks and trapped moisture;{{sfn|Osborne-Lee|1995|pp=26–27}}<!-- NEEDS CITE in airport [[prompt gamma neutron activation analysis|neutron-activation]] detectors of explosives, --> and in portable metal detectors.<ref>{{cite web|url=http://www.pnl.gov/news/2000/00-43.htm|title=Will You be 'Mine'? Physics Key to Detection|date=October 25, 2000|publisher = Pacific Northwest National Laboratory|access-date = March 21, 2007 |archive-url = https://web.archive.org/web/20070218125029/http://www.pnl.gov/news/2000/00-43.htm <!-- Bot retrieved archive --> |archive-date = February 18, 2007 }}</ref> [[Neutron moisture gauge]]s use {{sup|252}}Cf to find water and petroleum layers in oil wells, as a portable [[neutron source]] for gold and silver prospecting for on-the-spot analysis,{{sfn|CRC|2006|p=4.8}} and to detect ground water movement.<ref>{{cite journal|journal = Ground Water|volume = 18|issue = 1|pages =14–23|date = 2006|title =Ground-Water Tracers – A Short Review|author = Davis, S. N. |doi = 10.1111/j.1745-6584.1980.tb03366.x|last2 = Thompson|first2 = Glenn M.|last3 = Bentley|first3 = Harold W.|last4 = Stiles|first4 = Gary }}</ref> The main uses of {{sup|252}}Cf in 1982 were, reactor start-up (48.3%), fuel rod scanning (25.3%), and activation analysis (19.4%).{{sfn|Osborne-Lee|1995|p=12}} By 1994, most {{sup|252}}Cf was used in neutron radiography (77.4%), with fuel rod scanning (12.1%) and reactor start-up (6.9%) as important but secondary uses.{{sfn|Osborne-Lee|1995|p=12}} In 2021, fast neutrons from {{sup|252}}Cf were used for wireless data transmission.<ref>{{cite journal|journal = Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment|volume = 1021|issue = 1|article-number = 165946|date = 2022|title = Wireless information transfer with fast neutrons|author = Joyce, Malcolm J.|last2 = Aspinall|first2 = Michael D.|last3 = Clark|first3 = Mackenzie|last4 = Dale|first4 = Edward|last5 = Nye|first5 = Hamish|last6 = Parker|first6 = Andrew|last7 = Snoj|first7 = Luka|last8 = Spires|first8 = Joe|doi = 10.1016/j.nima.2021.165946| bibcode=2022NIMPA102165946J | s2cid=240341300 |issn=0168-9002 |doi-access = free}}</ref> | ||
=== Superheavy element production === | === Superheavy element production === | ||
{{See also|Superheavy element#Synthesis of superheavy nuclei}} | {{See also|Superheavy element#Synthesis of superheavy nuclei}} | ||
In October 2006, researchers announced that three atoms of [[oganesson]] (element 118) had been identified at [[Joint Institute for Nuclear Research]] in [[Dubna]], [[Russia]], from bombarding {{sup|249}}Cf with [[calcium-48]], making it the heaviest element ever made. The target contained about 10 mg of {{sup|249}}Cf deposited on a titanium foil of 32 cm{{sup|2}} area.<ref>{{cite journal |title = Synthesis of the isotopes of elements 118 and 116 in the californium-249 and <sup>245</sup>Cm+<sup>48</sup>Ca fusion reactions |journal = Physical Review C |date = 2006 |volume = 74 |issue =4 |pages = 044602–044611 |doi = 10.1103/PhysRevC.74.044602 |bibcode=2006PhRvC..74d4602O |last1=Oganessian |first1=Yu. Ts. |last2=Utyonkov |first2=V. |last3=Lobanov |first3=Yu. |last4=Abdullin |first4=F. |last5=Polyakov |first5=A. |last6=Sagaidak |first6=R. |last7=Shirokovsky |first7=I. |last8=Tsyganov |first8=Yu. |last9=Voinov |first9=A. |display-authors=8 |doi-access=free}}</ref><ref>{{cite journal |author = Sanderson, K. |title = Heaviest element made – again |journal = Nature News |publisher =Nature |date = October 17, 2006 |doi=10.1038/news061016-4 |s2cid = 121148847}}</ref><ref>{{cite web|author=Schewe, P. |author2=Stein, B. |title=Elements 116 and 118 Are Discovered |work=Physics News Update |publisher=American Institute of Physics |date=October 17, 2006 |url=http://www.aip.org/pnu/2006/797.html |access-date=October 19, 2006 | In October 2006, researchers announced that three atoms of [[oganesson]] (element 118) had been identified at [[Joint Institute for Nuclear Research]] in [[Dubna]], [[Russia]], from bombarding {{sup|249}}Cf with [[calcium-48]], making it the heaviest element ever made. The target contained about 10 mg of {{sup|249}}Cf deposited on a titanium foil of 32 cm{{sup|2}} area.<ref>{{cite journal |title = Synthesis of the isotopes of elements 118 and 116 in the californium-249 and <sup>245</sup>Cm+<sup>48</sup>Ca fusion reactions |journal = Physical Review C |date = 2006 |volume = 74 |issue =4 |pages = 044602–044611 |doi = 10.1103/PhysRevC.74.044602 |bibcode=2006PhRvC..74d4602O |last1=Oganessian |first1=Yu. Ts. |last2=Utyonkov |first2=V. |last3=Lobanov |first3=Yu. |last4=Abdullin |first4=F. |last5=Polyakov |first5=A. |last6=Sagaidak |first6=R. |last7=Shirokovsky |first7=I. |last8=Tsyganov |first8=Yu. |last9=Voinov |first9=A. |display-authors=8 |doi-access=free}}</ref><ref>{{cite journal |author = Sanderson, K. |title = Heaviest element made – again |journal = Nature News |publisher =Nature |date = October 17, 2006 |doi=10.1038/news061016-4 |s2cid = 121148847}}</ref><ref>{{cite web|author=Schewe, P. |author2=Stein, B. |title=Elements 116 and 118 Are Discovered |work=Physics News Update |publisher=American Institute of Physics |date=October 17, 2006 |url=http://www.aip.org/pnu/2006/797.html |access-date=October 19, 2006 |archive-url=https://web.archive.org/web/20061026072537/http://www.aip.org/pnu/2006/797.html |archive-date=October 26, 2006 }}</ref> <!-- EXPLAIN Calibration, [[dosimetry]], and fission fragment and half-life studies are other applications of californium.{{sfn|Osborne-Lee|1995|p=34}} --> Californium has also been used to produce other transuranic elements; for example, [[lawrencium]] was first synthesized in 1961 by bombarding californium with [[boron]] nuclei.<ref>{{cite journal|title = Element 103 Synthesized|journal = Science News-Letter|volume = 79|issue = 17|date=April 1961|page = 259|doi = 10.2307/3943043|author1 = <Please add first missing authors to populate metadata.> |jstor = 3943043}}</ref> | ||
=== Hypothetical nuclear weapons === | === Hypothetical nuclear weapons === | ||
{{See also|Nuclear weapon design#Minor actinide fission weapons}} | {{See also|Nuclear weapon design#Minor actinide fission weapons}} | ||
{{SimpleNuclide|Californium|251|link=yes}} has a very small calculated [[critical mass]] of about {{convert|5|kg|0|abbr=on}},<ref>{{cite web |title=Evaluation of nuclear criticality safety data and limits for actinides in transport |url=http://ec.europa.eu/energy/nuclear/transport/doc/irsn_sect03_146.pdf | {{SimpleNuclide|Californium|251|link=yes}} has a very small calculated [[critical mass]] of about {{convert|5|kg|0|abbr=on}},<ref>{{cite web |title=Evaluation of nuclear criticality safety data and limits for actinides in transport |url=http://ec.europa.eu/energy/nuclear/transport/doc/irsn_sect03_146.pdf |archive-url=https://web.archive.org/web/20110519171204/http://ec.europa.eu/energy/nuclear/transport/doc/irsn_sect03_146.pdf |archive-date=May 19, 2011 |access-date=December 20, 2010 |publisher=Institut de Radioprotection et de Sûreté Nucléaire |page=16}}</ref> high lethality, and a relatively short period of toxic environmental irradiation. The low critical mass of californium led to some exaggerated claims about possible uses for the element.{{efn|An article entitled "Facts and Fallacies of World War III" in the July 1961 edition of ''[[Popular Science]]'' magazine read "A californium atomic bomb need be no bigger than a pistol bullet. You could build a hand-held six-shooter to fire bullets that would explode on contact with the force of 10 tons of TNT."<ref>{{cite journal|journal=[[Popular Science]]|pages= 92–95, 178–181|date=July 1961|volume=179|issue=1|issn=0161-7370|title=Facts and Fallacies of World War III|url=https://books.google.com/books?id=OiEDAAAAMBAJ&pg=PA180|author1=Mann, Martin}}"force of 10 tons of TNT" on page 180.</ref>}} | ||
== Precautions == | == Precautions == | ||