Americium-242


Americium-242

Americium-242m is a radioactive isotope of Americium with 95 protons and electrons and 147 neutrons and a mass of 242.0595492 g/mol. It has a half-life of approximately 141 years, decaying:
#99.54% of the time by isomeric transition (with a decay energy of 0.05MeV) to its short-lived nuclear isomer americium-242
#0.46% of the time by emitting an alpha particle (the decay energy is 5.64 MeV) to turn into Neptunium-238
#very rarely by spontaneous fission (halflife (9.5±3.5)×1011 years) [ [http://prola.aps.org/abstract/PR/v155/i4/p1309_1 Phys. Rev. 155 (1967): J. T. Caldwell, S. C. Fultz, C. D. Bowman, and R. W. Hoff - Spontaneous Fission Half-Life of ] ]

242mAm is fissile (because it has an odd number of neutrons) and has a low critical mass, comparable to that of plutonium-239. [http://typhoon.jaea.go.jp/icnc2003/Proceeding/paper/6.5_022.pdf] It has a very high cross section for fission, and if in a nuclear reactor is destroyed relatively quickly.

Another report claims that 242mAm has a much lower critical mass, can sustain a chain reaction even as a thin film, and could be used for a novel type of nuclear rocket. [ [http://www.sciencedaily.com/releases/2001/01/010103073253.htm Extremely Efficient Nuclear Fuel Could Take Man To Mars In Just Two Weeks ] ]

Americium-242 has a half-life of 16 hours. This is one of the rare cases when a lower-energy nuclear isomer is less stable than the higher-energy one. It decays: [ [http://www.matpack.de/Info/Nuclear/Nuclids/A/Am242.html 95-Am-242 ] ]
#82.70% of the time, by beta decay to curium-242
#17.30% of the time, by electron capture to plutonium-242

ee also

* Americium
* Isotopes of americium


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Look at other dictionaries:

  • Américium 242 — Américium 242m L américium 242m, noté 242mAm[1], est un isomère nucléaire de l isotope de l américium dont le nombre de masse est égal à 242 : son noyau atomique compte 95 protons et 147 neutrons avec un spin 5 pour une masse… …   Wikipédia en Français

  • Americium — Américium Américium Plutoni …   Wikipédia en Français

  • Américium — Plutonium ← Américium → Curium Eu …   Wikipédia en Français

  • Américium 242m — L américium 242m, noté 242mAm[1], est un isomère nucléaire de l isotope de l américium dont le nombre de masse est égal à 242 : son noyau atomique compte 95 protons et 147 neutrons avec un spin 5 pour une masse atomique de… …   Wikipédia en Français

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  • americium — An element obtained by the bombardment of uranium with neutrons or β decay of plutoniums 241, 242, and 243; atomic no. 95; atomic weight 243.06. 241Am (half life of 432.2 years) has been used in the diagnosis of bone disorders. 243Am has a half… …   Medical dictionary

  • Curium 242 — Le Curium 242, noté 242Cm, est l isotope du Curium dont le nombre de masse est égal à 242 : son noyau atomique compte 96 protons et 146 neutrons avec un spin 0+ pour une masse atomique de 242,0588293 g/mol. Il est caractérisé par un… …   Wikipédia en Français

  • CURIUM — Le curium est un élément chimique artificiel dont le symbole est Cm et le numéro atomique 96. Il se situe, dans la classification périodique, parmi les éléments dits transuraniens. Son nom fut proposé en hommage aux savants français Pierre et… …   Encyclopédie Universelle

  • Plutonium-241 — Infobox isotope alternate names = symbol =Pu mass number =241 mass = num neutrons =147 num protons =94 abundance =0 (Artificial) halflife = 14 years error halflife = background =#7F7 text color = decay product =Americium 241 decay symbol =Am… …   Wikipedia

  • transuranium element — Any of the chemical elements after uranium in the periodic table (with atomic numbers greater than 92). All are radioactive (see radioactivity), with half lives ranging from tens of millions of years to fractions of a millisecond. Only two,… …   Universalium


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