Geiger-Briggs rule

Geiger-Briggs rule

[¦gī·gər ′brigz ‚rül]
(nucleonics)
The rule that the range of an alpha ray in dry air, at 15°C and 1 atmosphere, above 5 centimeters, is proportional to its initial velocity raised to the 3.26 power; an improvement on the Geiger formula.