Bethe–Feynman formula

The Bethe–Feynman efficiency formula, a simple method for calculating the yield of a fission bomb, was first derived in 1943 after development in 1942. Aspects of the formula are speculated to be secret restricted data.

${\displaystyle a\approx (bc)^{2}f}$

A numerical coefficient would then be included to create the Bethe–Feynman formula—increasing accuracy more than an order of magnitude.

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