Otto Hahn and the Rise of Nuclear Physics

and less as the emanation unden\''ent radioactive decay, and it became motion­ less after about 30 seconds. Since this process was occurring very rapidly, Hahn and Sackur marked the position of the pointer on a scale with pencil marks. As a timing device they used a metronome that beat out intervals of approximately 1. 3 seconds. This simple method enabled them to determine that the half-life of t...