Editing Curium (section)

==Applications==
===Radionuclides===
[[File:Curium self-glow radiation.jpg|thumb|right|[[Ionized air glow]] from curium alpha-radiation creates a purple aura in the dark.]]
Curium is one of the most radioactive isolable elements. Its two most common isotopes <sup>242</sup>Cm and <sup>244</sup>Cm are strong alpha emitters (energy 6&nbsp;MeV); they have fairly short half-lives, 162.8 days and 18.1 years, and give as much as 120&nbsp;W/g and 3&nbsp;W/g of heat, respectively.<ref name="CRC" /><ref name="Binder">Binder, Harry H.: ''Lexikon der chemischen Elemente'', S. Hirzel Verlag, Stuttgart 1999, {{ISBN|3-7776-0736-3}}, pp.&nbsp;174–178.</ref><ref>''Gmelin Handbook of Inorganic Chemistry'', System No. 71, Volume 7a, transuranics, Part A2, p. 289</ref> Therefore, curium can be used in its common oxide form in [[radioisotope thermoelectric generator]]s like those in spacecraft. This application has been studied for the <sup>244</sup>Cm isotope, while <sup>242</sup>Cm was abandoned due to its prohibitive price, around 2000&nbsp;USD/g. <sup>243</sup>Cm with a ~30-year half-life and good energy yield of ~1.6&nbsp;W/g could be a suitable fuel, but it gives significant amounts of harmful [[Gamma ray|gamma]] and [[Beta particle|beta]] rays from radioactive decay products. As an α-emitter, <sup>244</sup>Cm needs much less radiation shielding, but it has a high spontaneous fission rate, and thus a lot of neutron and gamma radiation. Compared to a competing thermoelectric generator isotope such as <sup>238</sup>Pu, <sup>244</sup>Cm emits 500 times more neutrons, and its higher gamma emission requires a shield that is 20 times thicker—{{convert|2|in|mm}} of lead for a 1&nbsp;kW source, compared to {{convert|0.1|in|mm}} for <sup>238</sup>Pu. Therefore, this use of curium is currently considered impractical.<ref name="lect">[http://fti.neep.wisc.edu/neep602/SPRING00/lecture5.pdf Basic elements of static RTGs] {{Webarchive|url=https://web.archive.org/web/20130215003518/http://fti.neep.wisc.edu/neep602/SPRING00/lecture5.pdf |date=2013-02-15 }}, G.L. Kulcinski, NEEP 602 Course Notes (Spring 2000), Nuclear Power in Space, University of Wisconsin Fusion Technology Institute (see last page)</ref>

A more promising use of <sup>242</sup>Cm is for making <sup>238</sup>Pu, a better radioisotope for thermoelectric generators such as in heart pacemakers. The alternate routes to <sup>238</sup>Pu use the (n,γ) reaction of <sup>237</sup>Np, or [[deuterium|deuteron]] bombardment of uranium, though both reactions always produce <sup>236</sup>Pu as an undesired by-product since the latter decays to <sup>232</sup>U with strong gamma emission.<ref>[http://www.kronenberg.kernchemie.de/ Kronenberg, Andreas], [http://www.kernenergie-wissen.de/pu-batterien.html Plutonium-Batterien] {{Webarchive|url=https://web.archive.org/web/20131226011403/http://www.kernenergie-wissen.de/pu-batterien.html |date=2013-12-26 }} (in German)

 {{Cite web |url=http://www.kronenberg.kernchemie.de/ |title=Archived copy |access-date=April 28, 2011 |archive-url=https://web.archive.org/web/20110221040021/http://www.kronenberg.kernchemie.de/ |archive-date=February 21, 2011 |url-status=bot: unknown |df=mdy-all }}</ref> Curium is a common starting material for making higher [[transuranium element|transuranic]] and [[superheavy element]]s. Thus, bombarding <sup>248</sup>Cm with neon (<sup>22</sup>Ne), magnesium (<sup>26</sup>Mg), or calcium ([[calcium-48|<sup>48</sup>Ca]]) yields isotopes of [[seaborgium]] (<sup>265</sup>Sg), [[hassium]] (<sup>269</sup>Hs and <sup>270</sup>Hs), and [[livermorium]] (<sup>292</sup>Lv, <sup>293</sup>Lv, and possibly <sup>294</sup>Lv).<ref name="HOWI_1980">Holleman, pp. 1980–1981.</ref> Californium was discovered when a microgram-sized target of curium-242 was irradiated with 35&nbsp;MeV [[alpha particle]]s using the {{convert|60|in|cm|adj=on}} cyclotron at Berkeley:
:{{nuclide|curium|242}} + {{nuclide|helium|4}} → {{nuclide|californium|245}} + {{nuclide|neutronium|1}}
Only about 5,000 atoms of californium were produced in this experiment.<ref>{{cite book|title=One Hundred Years after the Discovery of Radioactivity|editor=Adloff, J. P.|last=Seaborg|first=Glenn T.|page=82|date=1996|publisher=Oldenbourg Wissenschaftsverlag|isbn=978-3-486-64252-0}}</ref>

The odd-mass curium isotopes <sup>243</sup>Cm, <sup>245</sup>Cm, and <sup>247</sup>Cm are all highly [[fissile material|fissile]] and can release additional energy in a thermal spectrum [[nuclear reactor]]. All curium isotopes are fissionable in fast-neutron reactors. This is one of the motives for [[minor actinide]] separation and transmutation in the [[nuclear fuel cycle]], helping to reduce the long-term radiotoxicity of used, or [[spent nuclear fuel]].{{Citation needed|date=April 2025}}

[[File:MER APXS PIA05113.jpg|thumb|Alpha-particle X-ray spectrometer of a Mars exploration rover]]

===X-ray spectrometer===
The most practical application of <sup>244</sup>Cm—though rather limited in total volume—is as α-particle source in [[alpha particle X-ray spectrometer]]s (APXS). These instruments were installed on the [[Mars Pathfinder|Sojourner]], [[Mars rover|Mars]], [[Mars 96]], [[Mars Exploration Rover]]s and [[Philae (spacecraft)|Philae comet lander]],<ref>{{cite web|url=http://www.bernd-leitenberger.de/philae.shtml |title=Der Rosetta Lander Philae |publisher=Bernd-leitenberger.de |date=2003-07-01 |access-date=2011-03-25}}</ref> as well as the [[Mars Science Laboratory]] to analyze the composition and structure of the rocks on the surface of planet [[Mars]].<ref>{{cite journal|bibcode=1996DPS....28.0221R|title=An Alpha Proton X-Ray Spectrometer for Mars-96 and Mars Pathfinder|author=Rieder, R.|author2=Wanke, H.|author3=Economou, T.|journal=Bulletin of the American Astronomical Society|volume=28|page=1062|date=September 1996}}</ref> APXS was also used in the [[Surveyor program|Surveyor 5–7]] moon probes but with a <sup>242</sup>Cm source.<ref name="LA2">[http://www.ead.anl.gov/pub/doc/curium.pdf Human Health Fact Sheet on Curium] {{Webarchive|url=https://web.archive.org/web/20060218162709/http://www.ead.anl.gov/pub/doc/curium.pdf |date=2006-02-18 }}, Los Alamos National Laboratory</ref><ref>Leitenberger, Bernd [http://www.bernd-leitenberger.de/surveyor.shtml Die Surveyor Raumsonden] (in German)</ref><ref>{{cite book|chapter-url=https://history.nasa.gov/SP-480/ch9.htm |author=Nicks, Oran |
chapter=Ch. 9. Essentials for Surveyor|publisher=NASA|date=1985|title=SP-480 Far Travelers: The Exploring Machines}}</ref>

An elaborate APXS setup has a sensor head containing six curium sources with a total decay rate of several tens of [[Curie (unit)|millicuries]] (roughly one [[gigabecquerel]]). The sources are collimated on a sample, and the energy spectra of the alpha particles and protons scattered from the sample are analyzed (proton analysis is done only in some spectrometers). These spectra contain quantitative information on all major elements in the sample except for hydrogen, helium and lithium.<ref>[https://web.archive.org/web/20060302040531/http://athena.cornell.edu/pdf/tb_apxs.pdf Alpha Particle X-Ray Spectrometer (APXS)], Cornell University</ref>