Hans_Geiger--Hans_Albrecht_Bethe

Johannes Wilhelm "Hans" Geiger (; German: [ˈɡaɪɡɐ]; 30 September 1882 – 24 September 1945) was a German physicist. He is best known as the co-inventor of the detector component of the Geiger counter and for the Geiger–Marsden experiment which discovered the atomic nucleus. He also carried the Bothe–Geiger coincidence experiment that confirmed the conservation of energy in light-particle interactions.
He was the brother of meteorologist and climatologist Rudolf Geiger.