Bethe–Feynman formula
The Bethe–Feynman efficiency formula, a simple method for calculating the yield of a fission bomb,{{Cite web|url=http://nuclearweaponarchive.org/Nwfaq/Nfaq4-1.html|title = 4.1 Elements of Fission Weapon Design}} was first derived in 1943 after development in 1942. Aspects of the formula are speculated to be secret restricted data.[http://www.webofstories.com/play/hans.bethe/92 Meeting and working with Richard Feynman at Los Alamos], Web of Stories, story by Hans Bethe recorded in December 1996, last accessed 2015/04/20.
Related formula
- a = internal energy per gram
- b = growth rate
- c = sphere radius
A numerical coefficient would then be included to create the Bethe–Feynman formula—increasing accuracy by more than an order of magnitude.{{cite book|author=Hans Volland |year=1995 |title=Handbook of atmospheric electrodynamics, Volume 2
|publisher=CRC Press |isbn=0-8493-2520-X}}
where γ is the thermodynamic exponent of a photon gas, {{math|E{{sub|2}}}} is the prompt energy density of the fuel, α is V{{sub|n}} (neutron velocity) / λ{{sub|mfp{{sub|tot}}}} (total reaction mean free path), R{{sub|crit}} is the critical radius and 𝛿 is the excess supercritical radius {{math| (R{{sub|core}} - R{{sub|crit}}) / R{{sub|crit}}}}.
See also
References
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{{Richard Feynman|state=collapsed}}
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