Editing Einsteinium (section)

==History==
[[File:Ivy Mike - mushroom cloud.jpg|thumb|left|Einsteinium was first observed in the fallout from the ''Ivy Mike'' nuclear test.]]
Einsteinium was [[timeline of chemical element discoveries|first identified]] in December 1952 by [[Albert Ghiorso]] and co-workers at [[University of California, Berkeley]] in collaboration with the [[Argonne National Laboratory|Argonne]] and [[Los Alamos National Laboratory|Los Alamos]] National Laboratories, in the fallout from the ''[[Ivy Mike]]'' nuclear test. The test was done on November 1, 1952, at [[Enewetak Atoll]] in the [[Pacific Ocean]] and was the first successful test of a [[thermonuclear weapon]].<ref name="Ghiorso" /> Initial examination of the debris from the explosion had shown the production of a new isotope of [[plutonium]], {{nuclide|Pu|Z=94|A=244}}, which could only have formed by the absorption of six [[neutron]]s by a [[uranium-238]] nucleus followed by two [[beta decay]]s.
:<chem>^{238}_{92}U ->[\ce{+ 6(n,\gamma)}][-2\ \beta^-]{} ^{244}_{94}Pu</chem>
At the time, the multiple neutron absorption was thought to be an extremely rare process, but the identification of {{sup|244}}Pu indicated that still more neutrons could have been captured by the uranium, producing new elements heavier than [[californium]].<ref name="Ghiorso">{{cite journal|first = Albert|last = Ghiorso|author-link = Albert Ghiorso|date = 2003|title = Einsteinium and Fermium|journal = Chemical and Engineering News|url = http://pubs.acs.org/cen/80th/einsteiniumfermium.html|volume = 81|issue = 36|doi = 10.1021/cen-v081n036.p174|pages = 174–175|access-date = 2007-04-15|archive-date = 2018-09-06|archive-url = https://web.archive.org/web/20180906064329/http://pubs.acs.org/cen/80th/einsteiniumfermium.html|url-status = live}}</ref>

[[File:Albert Ghiorso ca 1970.jpg|thumb|left|upright|The element was discovered by a team headed by [[Albert Ghiorso]].]]
Ghiorso and co-workers analyzed filter papers which had been flown through the explosion cloud on airplanes (the same sampling technique that had been used to discover {{sup|244}}Pu).<ref name="s39">[[#Seaborg|Seaborg]], p. 39</ref> Larger amounts of radioactive material were later isolated from coral debris of the atoll, and these were delivered to the U.S.<ref name="Ghiorso" /> The separation of suspected new elements was carried out in the presence of a [[citric acid]]/[[ammonium]] [[buffer solution]] in a weakly acidic medium ([[pH]] ≈ 3.5), using [[ion exchange]] at elevated temperatures; fewer than 200 atoms of einsteinium were recovered in the end.<ref name="em">{{cite book|author=John Emsley|url=https://books.google.com/books?id=j-Xu07p3cKwC&pg=PA133|title=Nature's building blocks: an A-Z guide to the elements|archive-url=https://web.archive.org/web/20160609222635/https://books.google.com/books?id=j-Xu07p3cKwC&pg=PA133|archive-date=2016-06-09|publisher=Oxford University Press|year=2003|isbn=0-19-850340-7|pages=133–135}}</ref> Nevertheless, element 99, einsteinium, and in particular {{sup|253}}Es, could be detected via its characteristic high-energy [[alpha decay]] at 6.6&nbsp;MeV.<ref name = "Ghiorso" /> It was produced by the [[neutron capture|capture]] of 15 [[neutron]]s by [[uranium-238]] nuclei followed by seven beta decays, and had a [[half-life]] of 20.5 days. Such multiple neutron absorption was made possible by the high neutron flux density during the detonation, so that newly generated heavy isotopes had plenty of available neutrons to absorb before they could disintegrate into lighter elements. Neutron capture initially raised the [[mass number]] without changing the [[atomic number]] of the nuclide, and the concomitant beta-decays resulted in a gradual increase in the atomic number:<ref name="Ghiorso" />
:<chem>
^{238}_{92}U ->[\ce{+15n}][6 \beta^-] ^{253}_{98}Cf ->[\beta^-] ^{253}_{99}Es
</chem>

Some {{sup|238}}U atoms, however, could absorb two additional neutrons (for a total of 17), resulting in {{sup|255}}Es, as well as in the {{sup|255}}Fm isotope of another new element, [[fermium]].<ref>{{sup|254}}Es, {{sup|254}}Fm and {{sup|253}}Fm would not be produced because of lack of beta decay in {{sup|254}}Cf and {{sup|253}}Es</ref> The discovery of the new elements and the associated new data on multiple neutron capture were initially kept secret on the orders of the U.S. military until 1955 due to [[Cold War]] tensions and competition with Soviet Union in nuclear technologies.<ref name="Ghiorso" /><ref name = "ES_FM">{{cite journal|last1 = Ghiorso|first1 = A.|last2 = Thompson|first2 = S.|last3 = Higgins|first3 = G.|last4 = Seaborg|first4 = G.|last5 = Studier|first5 = M.|last6 = Fields|first6 = P.|last7 = Fried|first7 = S.|last8 = Diamond|first8 = H.|last9 = Mech|first9 = J.|first10 = G.|last10 = Pyle|first11 = J.|last11 = Huizenga|first12 = A.|last12 = Hirsch|first13 = W.|last13 = Manning|first14 = C.|last14 = Browne|first15 = H.|last15 = Smith|first16 = R.|last16 = Spence|title = New Elements Einsteinium and Fermium, Atomic Numbers 99 and 100|journal = Phys. Rev.|volume = 99|issue = 3|url = http://escholarship.org/uc/item/70q401ct|doi = 10.1103/PhysRev.99.1048|pages = 1048–1049|date = 1955|bibcode = 1955PhRv...99.1048G|access-date = 2010-11-24|archive-date = 2021-05-19|archive-url = https://web.archive.org/web/20210519093844/https://escholarship.org/uc/item/70q401ct|url-status = live|doi-access = free}} {{citation|url=https://books.google.com/books?id=e53sNAOXrdMC&pg=PA91|title=Modern Alchemy: Selected Papers of Glenn T. Seaborg|isbn=9789810214401 |archive-url=https://web.archive.org/web/20160413022543/https://books.google.com/books?id=e53sNAOXrdMC&pg=PA91|archive-date=2016-04-13 |last1=Seaborg |first1=Glenn Theodore |year=1994 |publisher=World Scientific }}</ref><ref>{{cite journal|last1=Fields|first1=P.|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. |first10 = G. |last10 = Pyle |first11 = J. |last11 = Huizenga |first12 = A. |last12 = Hirsch |first13 = W. |last13 = Manning |first14 = C. |last14 = Browne |first15 = H. |last15 = Smith |first16 = R. |last16 = Spence |title=Transplutonium Elements in Thermonuclear Test Debris|journal=Physical Review |volume=102|issue=1|date=1956|pages=180–182|doi=10.1103/PhysRev.102.180|bibcode = 1956PhRv..102..180F|isbn=978-981-02-1440-1 |url=https://books.google.com/books?id=e53sNAOXrdMC&pg=PA93|via=Google Books|archive-url=https://web.archive.org/web/20160423081455/https://books.google.com/books?id=e53sNAOXrdMC&pg=PA93|archive-date=2016-04-23 }}</ref> However, the rapid capture of so many neutrons would provide needed direct experimental confirmation <!--"convincing evidence of the reality of"--> of the [[r-process]] multi-neutron absorption needed to explain the cosmic [[nucleosynthesis]] (production) of certain heavy elements (heavier than nickel) in [[supernova]]s, before [[beta decay]]. Such a process is needed to explain the existence of many stable elements in the universe.<ref>{{cite book|author=Byrne, J.|title=Neutrons, Nuclei, and Matter|publisher=Dover Publications|location=Mineola, NY|year=2011|isbn=978-0-486-48238-5}} (pbk.) pp. 267.</ref>

Meanwhile, isotopes of element 99 (as well as of new element 100, [[fermium]]) were produced in the Berkeley and Argonne laboratories, in a [[nuclear fusion|nuclear reaction]] between [[nitrogen]]-14 and uranium-238,<ref name = "PhysRev.93.257">{{cite journal| journal = Physical Review| volume = 93|issue = 1| date = 1954|title = Reactions of U-238 with Cyclotron-Produced Nitrogen Ions| author = Ghiorso, Albert| author2 = Rossi, G. Bernard| author3 = Harvey, Bernard G.| author4 = Thompson, Stanley G.| s2cid = 121499772| name-list-style = amp| doi = 10.1103/PhysRev.93.257|pages = 257|bibcode = 1954PhRv...93..257G }}</ref> and later by intense neutron irradiation of [[plutonium]] or [[californium]]:
:<chem>^{252}_{98}Cf ->[\ce{(n,\gamma)}] ^{253}_{98}Cf ->[\beta^-][17.81 \ce{d}] ^{253}_{99}Es ->[\ce{(n,\gamma)}] ^{254}_{99}Es ->[\beta^-] ^{254}_{100}Fm</chem>

These results were published in several articles in 1954 with the disclaimer that these were not the first studies that had been carried out on the elements.<ref name = "PhysRev.93.908" >{{cite journal| journal = Physical Review| volume = 93| date = 1954| title = Transcurium Isotopes Produced in the Neutron Irradiation of Plutonium| author = Thompson, S. G.| author2 = Ghiorso, A.| author3 = Harvey, B. G.| author4 = Choppin, G. R.| doi = 10.1103/PhysRev.93.908| pages = 908| issue = 4| bibcode = 1954PhRv...93..908T| url = https://digital.library.unt.edu/ark:/67531/metadc1016991/| access-date = 2019-07-14| archive-date = 2020-03-16| archive-url = https://web.archive.org/web/20200316232939/https://digital.library.unt.edu/ark:/67531/metadc1016991/| url-status = live| doi-access = free}}</ref><ref>{{cite journal|last1=Harvey|first1=Bernard|last2=Thompson|first2=Stanley|last3=Ghiorso|first3=Albert|last4=Choppin|first4=Gregory|title=Further Production of Transcurium Nuclides by Neutron Irradiation|journal=Physical Review|volume=93|pages=1129|date=1954|doi=10.1103/PhysRev.93.1129|issue=5|bibcode=1954PhRv...93.1129H|url=http://www.escholarship.org/uc/item/7884m0gv|access-date=2019-07-14|archive-date=2020-03-09|archive-url=https://web.archive.org/web/20200309181708/https://escholarship.org/uc/item/7884m0gv|url-status=live}}</ref><ref>{{cite journal|last1=Studier|first1=M.|last2=Fields|first2=P.|last3=Diamond|first3=H.|last4=Mech|first4=J.|last5=Friedman|first5=A.|last6=Sellers|first6=P.|last7=Pyle|first7=G.|last8=Stevens|first8=C.|last9=Magnusson|first9=L.|first10=J.|last10=Huizenga |title=Elements 99 and 100 from Pile-Irradiated Plutonium|journal=Physical Review|volume=93|pages=1428|date=1954|doi=10.1103/PhysRev.93.1428|issue=6|bibcode = 1954PhRv...93.1428S }}</ref><ref>{{cite journal|first1 = G. R.|last1 = Choppin|first2 = S. G.|last2 = Thompson|first3 = A.|last3 = Ghiorso|author-link3 = Albert Ghiorso|first4 = B. G.|last4 = Harvey|title = Nuclear Properties of Some Isotopes of Californium, Elements 99 and 100|journal = Physical Review|volume = 94|issue = 4|pages = 1080–1081|date = 1954|doi = 10.1103/PhysRev.94.1080|bibcode = 1954PhRv...94.1080C |doi-access = free}}</ref><ref>{{cite journal|last1=Fields|first1=P.|last2=Studier|first2=M.|last3=Mech|first3=J.|last4=Diamond|first4=H.|last5=Friedman|first5=A.|last6=Magnusson|first6=L.|last7=Huizenga|first7=J.|title=Additional Properties of Isotopes of Elements 99 and 100|journal=Physical Review|volume=94|issue=1|pages=209–210|date=1954|doi=10.1103/PhysRev.94.209|bibcode = 1954PhRv...94..209F }}</ref> The Berkeley team also reported some results on the chemical properties of einsteinium and fermium.<ref name="Properties_1">{{citation|author=Seaborg, G. T.; Thompson, S.G.; Harvey, B.G. and Choppin, G.R.|date=July 23, 1954|url=http://www.osti.gov/accomplishments/documents/fullText/ACC0047.pdf|title=Chemical Properties of Elements 99 and 100|journal=Journal of the American Chemical Society |volume=76 |issue=24 |page=6229 |doi=10.1021/ja01653a004 |bibcode=1954JAChS..76.6229T |archive-url=https://web.archive.org/web/20190710170811/http://www.osti.gov/accomplishments/documents/fullText/ACC0047.pdf|archive-date=2019-07-10}} Radiation Laboratory, University of California, Berkeley, UCRL-2591</ref><ref name="Properties_2">{{cite journal|title=Chemical Properties of Elements 99 and 100|last1=Thompson|first1=S. G.|last2=Harvey|first2=B. G.|last3=Choppin|first3=G. R.|last4=Seaborg|first4=G. T.|journal=Journal of the American Chemical Society|volume=76|pages=6229–6236|date=1954|doi=10.1021/ja01653a004|issue=24|bibcode=1954JAChS..76.6229T |url=https://digital.library.unt.edu/ark:/67531/metadc1023183/|access-date=2019-07-14|archive-date=2019-10-20|archive-url=https://web.archive.org/web/20191020212317/https://digital.library.unt.edu/ark:/67531/metadc1023183/|url-status=live}}</ref> The ''Ivy Mike'' results were declassified and published in 1955.<ref name = "ES_FM" />

[[File:Einstein1921 by F Schmutzer 2.jpg|thumb|right|upright|The element was named after [[Albert Einstein]].]]
In their discovery of elements 99 and 100, the American teams had competed with a group at the Nobel Institute for Physics, [[Stockholm]], [[Sweden]]. In late 1953 – early 1954, the Swedish group succeeded in synthesizing light isotopes of element 100, in particular {{sup|250}}Fm, by bombarding uranium with oxygen nuclei. These results were also published in 1954.<ref>{{cite journal|last1=Atterling|first1=Hugo|last2=Forsling|first2=Wilhelm|last3=Holm|first3=Lennart|last4=Melander|first4=Lars|last5=Åström|first5=Björn|title=Element 100 Produced by Means of Cyclotron-Accelerated Oxygen Ions|journal=Physical Review|volume=95|pages=585–586|date=1954|doi=10.1103/PhysRev.95.585.2|issue=2|bibcode = 1954PhRv...95..585A }}</ref> Nevertheless, the priority of the Berkeley team was generally recognized, as its publications preceded the Swedish article, and they were based on the previously undisclosed results of the 1952 thermonuclear explosion; thus the Berkeley team was given the privilege to name the new elements. As the effort which had led to the design of ''Ivy Mike'' was codenamed Project PANDA,<ref name="underthecloud">{{cite book |title=Under the cloud: the decades of nuclear testing |author=Richard Lee Miller |page=115 |isbn=978-1-881043-05-8 |publisher=Two-Sixty Press |date=1991}}</ref> element 99 had been jokingly nicknamed "Pandemonium"<!-- sic: /not/ pandemonium --><ref name="mcphee">{{cite book |title=The Curve of Binding Energy |first=John |last=McPhee |author-link=John McPhee |page=116 |publisher=Farrar, Straus & Giroux Inc. |isbn=978-0-374-51598-0 |date=1980}}</ref> but the official names suggested by the Berkeley group derived from two prominent scientists, Einstein and Fermi: "We suggest for the name for the element with the atomic number 99, einsteinium (symbol E) after [[Albert Einstein]] and for the name for the element with atomic number 100, fermium (symbol Fm), after [[Enrico Fermi]]."<ref name = "ES_FM " /> Both Einstein and Fermi died between the time the names were originally proposed and when they were announced. The discovery of these new elements was announced by [[Albert Ghiorso]] at the first Geneva Atomic Conference held on 8–20 August 1955.<ref name="Ghiorso" /> The symbol for einsteinium was first given as "E" and later changed to "Es" by IUPAC.<ref name="h1577">[[#Haire|Haire]], p. 1577</ref><ref name="se6">{{cite book|author=Seaborg, G.T.|year=1994|url=https://books.google.com/books?id=e53sNAOXrdMC&pg=PA6|title=Modern alchemy: selected papers of Glenn T. Seaborg|archive-url=https://web.archive.org/web/20160609194723/https://books.google.com/books?id=e53sNAOXrdMC&pg=PA6|archive-date=2016-06-09|publisher=World Scientific|page=6|isbn=981-02-1440-5}}.</ref>