Editing Einsteinium (section)

===Synthesis in nuclear explosions===
[[File:ActinideExplosionSynthesis.png|thumb|upright=1.4|left|Estimated yield of transuranium elements in the U.S. nuclear tests Hutch and Cyclamen<ref name="s40" />]]
The analysis of the debris at the 10-[[TNT equivalent|megaton]] ''Ivy Mike'' nuclear test was a part of long-term project. One of the goals was studying the efficiency of production of transuranic elements in high-power nuclear explosions. The motive for these experiments was that synthesis of such elements from uranium requires multiple neutron capture. The probability of such events increases with the [[neutron flux]], and nuclear explosions are the most powerful man-made neutron sources, providing densities of the order 10{{sup|23}} neutrons/cm{{sup|2}} within a microsecond, or about 10{{sup|29}} neutrons/(cm{{sup|2}}·s). In comparison, the flux of HFIR is 5{{e|15}} neutrons/(cm{{sup|2}}·s). A dedicated laboratory was set up right at [[Enewetak Atoll]] for preliminary analysis of debris, as some isotopes could have decayed by the time the debris samples reached the mainland U.S. The laboratory was receiving samples for analysis as soon as possible, from airplanes equipped with paper filters which flew over the atoll after the tests. Whereas it was hoped to discover new chemical elements heavier than fermium, none of these were found even after a series of megaton explosions conducted between 1954 and 1956 at the atoll.<ref name="s39" />

The atmospheric results were supplemented by the underground test data accumulated in the 1960s at the [[Nevada Test Site]], as it was hoped that powerful explosions in a confined space might give improved yields and heavier isotopes. Apart from traditional uranium charges, combinations of uranium with americium and [[thorium]] have been tried, as well as a mixed plutonium-neptunium charge, but they were less successful in terms of yield and was attributed to stronger losses of heavy isotopes due to enhanced fission rates in heavy-element charges. Product isolation was problematic as the explosions were spreading debris through melting and vaporizing the surrounding rocks at depths of 300–600 meters. Drilling to such depths to extract the products was both slow and inefficient in terms of collected volumes.<ref name="s39" /><ref name="s40">[[#Seaborg|Seaborg]], p. 40</ref>

Of the nine underground tests between 1962 and 1969,<ref>These were codenamed: "Anacostia" (5.2 [[TNT equivalent|kilotons]], 1962), "Kennebec" (<5 kilotons, 1963), "Par" (38 kilotons, 1964), "Barbel" (<20 kilotons, 1964), "Tweed" (<20 kilotons, 1965), "Cyclamen" (13 kilotons, 1966), "Kankakee" (20-200 kilotons, 1966), "Vulcan" (25 kilotons, 1966) and "Hutch" (20-200 kilotons, 1969)</ref><ref>[http://www.nv.doe.gov/library/publications/historical/DOENV_209_REV15.pdf United States Nuclear Tests July 1945 through September 1992] {{webarchive |url=https://web.archive.org/web/20100615231826/http://www.nv.doe.gov/library/publications/historical/DOENV_209_REV15.pdf |date=June 15, 2010 }}, DOE/NV--209-REV 15, December 2000.</ref> the last one was the most powerful and had the highest yield of transuranics. Milligrams of einsteinium that would normally take a year of irradiation in a high-power reactor, were produced within a microsecond.<ref name="s40" /> However, the major practical problem of the entire proposal was collecting the radioactive debris dispersed by the powerful blast. Aircraft filters adsorbed only ~4{{e|-14}} of the total amount, and collection of tons of corals at Enewetak Atoll increased this fraction by only two orders of magnitude. Extraction of about 500 kilograms of underground rocks 60 days after the Hutch explosion recovered only ~1{{e|-7}} of the total charge. The amount of transuranic elements in this 500-kg batch was only 30 times higher than in a 0.4-kg rock picked up 7 days after the test which showed the highly non-linear dependence of the transuranics yield on the amount of retrieved radioactive rock.<ref name="s43">[[#Seaborg|Seaborg]], p. 43</ref> Shafts were drilled at the site before the test in order to accelerate sample collection after explosion, so that explosion would expel radioactive material from the epicenter through the shafts and to collecting volumes near the surface. This method was tried in two tests and instantly provided hundreds of kilograms of material, but with actinide concentration 3 times lower than in samples obtained after drilling. Whereas such method could have been efficient in scientific studies of short-lived isotopes, it could not improve the overall collection efficiency of the produced actinides.<ref name="s44">[[#Seaborg|Seaborg]], p. 44</ref>

Though no new elements (except einsteinium and fermium) could be detected in the nuclear test debris, and the total yields of transuranics were disappointingly low, these tests did provide significantly higher amounts of rare heavy isotopes than previously available in laboratories.<!-- About 6E9 atoms of 257Fm could be recovered after the Hutch detonation. These were then used in the studies of thermal-neutron induced fission of 257Fm, and in discovery of a new nuclide, 258Fm. Also, the rare 250Cm isotope was synthesized in large quantities, which is very hard to produce in nuclear reactors from its progenitor 249Cm: 249Cm's half-life (64 minutes) is much too short for months-long reactor irradiation, but very "long" on the timescale of an explosion.--><ref name="s47">[[#Seaborg|Seaborg]], p. 47</ref>