Helmuth Kulenkampff

Helmuth Kulenkampff (5 December 1895 – 12 June 1971) was a physicist notable for his studies of X-rays. He obtained his PhD in 1922 under Ernst Wagner at the University of Munich with a thesis entitled: "Über das Kontinuierliche Röntgenspektrum" (On the continuous X-ray spectrum).
In 1937, Alfred Ehmert made the surprising observation that cosmic ray absorption in water is less than in air for same "effective" thickness. In 1938, Kulenkampff was the first to correctly explain this effect in terms of meson decay, and this then enabled Hans Heinrich Euler and Werner Heisenberg to calculate an improved figure for meson decay time.