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Theodor Wulf
Theodor Wulf in 1910
Born	(1868-07-28)28 July 1868 Hamm,North Rhine-Westphalia, Germany
Died	19 June 1946(1946-06-19) (aged 77) Hallenberg,Hochsauerland,North Rhine-Westphalia, Germany
Occupations	Physicist,priest

Theodor Wulf (28 July 1868 – 19 June 1946) was aGermanphysicist andJesuit priest who was one of the first experimenters to detect excessatmosphericradiation.

Theodor Wulf became a Jesuit priest at the age of 20, before studyingphysics withWalther Nernst at theUniversity of Göttingen. He taught physics atValkenburg, a Jesuit University from 1904 to 1914 and 1918-1935. He designed and built anelectrometer which could detect the presence of energetic charged particles (or electromagnetic waves). Since natural radiation sources on the ground were detected by his electrometer, he predicted that if he moved far enough away from those sources he would detect less radiation.

To test his hypothesis, in 1910 he compared the radiation at the bottom and the top of theEiffel Tower.^[1][2] He found that the ionisation fell from 6 ions cm⁻³ to 3.5 ions cm⁻³ as he ascended the Eiffel Tower (330m). If the ionisation had been due to γ-rays originating at the surface of the Earth, the intensity of ions should have halved in 80m.^[3] Energy was coming from outside the Earth's atmosphere and being detected by his device; this radiation was fromcosmic rays. He published a paper inPhysikalische Zeitschrift detailing the results of his four days of observation on the Eiffel Tower.^[1] His results were not initially accepted.

• Uber den Einfluss des Druckes auf die elektromotorische Kraft der Gaselektroden. Physikalische Zeitschrift Chemie
• About the radiation of high penetration capacity contained in the atmosphere. Physikalische Zeitschrift
• Einstein's relativity theory, 1921.
• Text book of physics, 1926.
• Electrostatic attempts with application of the universal electroscope, 1928.
• The oscillatory movement, 1931.
• The Thread Electrometers, 1933.
• The Components of the Body World, 1935.

• Radiant energy
• List of Jesuit scientists
• List of Roman Catholic scientist-clerics

• Johannes Madey (2000). "Wulf, Theodor". In Bautz, Traugott (ed.).Biographisch-Bibliographisches Kirchenlexikon (BBKL) (in German). Vol. 17. Herzberg: Bautz. cols. 1573–1574.ISBN 3-88309-080-8.
• Theodor Wulf: ""About the radiation of high penetration capacity contained in the atmosphere" Physikalische Zeitschrift, 10th year, no. 5, pages 152-157
• Victor F. Hess:"About Observations of the Penetration {through-going} Radiation During 7 Balloon Flights"
• Victor F. Hess:"About the absorption of gamma rays in the atmosphere"

• 19th-century German physicists
• 19th-century German Jesuits
• University of Göttingen alumni
• 20th-century German Jesuits
• 1868 births
• 1946 deaths
• Jesuit scientists
• 20th-century German physicists

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• CS1 German-language sources (de)