BornSchwiebus (Świebodzin, Poland), 28 December 1887
DiedMunich, Germany, 5 August 1946
Werner Kolhörster helped bring modern, quantitative methods to the study of cosmic rays.
Kolhörster earned his PhD in physics under the direction of Friedrich Ernst Dorn at the University of Halle in 1911. He then became interested in the discovery of cosmic rays in the Earth’s upper atmosphere by Austrian physicist Victor Hess , achieved by means of balloon ascensions (up to 5-km altitude) with an electrometer. Kolhörster extended the balloon-borne measurements up to 10-km altitude and fully demonstrated the validity of Hess’s conclusions. He remained an assistant at the Physical Institute in Halle until the outbreak of World War I. He spent the war years in Turkey measuring atmospheric electricity.
After the war, Kolhörster was forced into secondary teaching to support himself, at the Friedrich Werdersche Oberrealschule (circa 1920–1924) and the Sophien Realgymnasium, Berlin (circa 1924–1928). Nonetheless, Kolhörster became a guest investigator at the Physikalische-Technische Reichsanstalt in Berlin, where he significantly improved the instrumentation used to measure various types of radiation. He frequently tested his equipment in the Alps. In collaboration with physicist Walther Bothe, Kolhörster developed the so-called coincidence method of scintillation counting, for which he was awarded the Leibniz Medal of the Prussian Academy of Sciences. Their joint papers in 1928 and 1929 were important in establishing that cosmic rays are very high energy particles and not very short wavelength photons.
In 1928, Kolhörster was hired as an observer at the Magnetic-Meteorological Observatory at Potsdam. Two years later, he was appointed a Privatdozent (lecturer) in geophysics at the University of Berlin and concurrently designed the Dahlemer University Institute for High-altitude Radiation Research, the first such facility ever to be established. In 1935, Kolhörster became the laboratory’s director and professor of radiation physics. He shared in the discovery of air showers associated with the production of secondary cosmic rays.
With Leo Tuwim, Kolhörster wrote a leading text, Physakalische Probleme der Höhenstrahlung (Physical problems of high-altitude radiation).