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Ramsauer, Carl Wilhelm

RAMSAUER, CARL WILHELM

(b. Osternburg, Oldenburg, Germany, 6 February 1879; d. Berlin, Germany, 24 December 1955)

physics

The son of a Lutheran clergyman, Ramsauer gradated from secondary school in 1897. To prepare for a career as a Gymnasium teacher he studied mathematics and physics at the universities of Munich, Tübingen, and Kiel. He taught at a secondary school for a short period but soon decided on a career in science. In 1902 he received his doctorate from Kiel with a dissertation entitled “Über den Ricochetschuss”. Its subject, which he chose, was the ricochet of a projectile upon encountering a water surface. After four years at the torpedo laboratory in Kiel. Ramsauer went to Heidelberg in 1907, to study with Philipp Lenard, whom he had met at Kiel. In 1909 he became a researcher at the newly founded radiological institute of the did University of Heidelberg. He qualified as a university lecturer that same year with a Habilitationsschrift entitled “Experimentelle and theoretische Grundlagen des elastischen und mechanischen Stosses.” In 1915 Ramsauer was appointed extraordinary professor, and in 1921 he became full professor and director of the physiocs institute of the Technische Hochschule in Danzig. He gained internatioinal recognition for his discovery, in 1920, of the Ramsauer effect.

In 1927, while in Berlin, Ramsauer accepted an unexpected offer from the Allgemeine Elektrizitas-Gesellschaft(AEG) to establish and direct a research institute for the company. He held that post until the institute was closed at the end of World War II. He then became the director, with rank of full professor, of the physics institute of the Berlin Technische Hochschul, where he had been honorary professor since 1931. He retired in 1953.

Ramasuer received an honorary doctorate from the Technische Hochschule in Karlsruhe and was a corresponding member of the Academy of Sciences of Göttingen and of the German Academy of Aviation Research, Reacting to the decline and disregard of physics in Germany under the Naziregime, he lodged vehement protests with the minister of science at considerable personal risk.

From 1940 to 1945 Ramsauer was president of the German Physicis Society. His special interest in the teaching of physics in secondaruy schools is shown in his Grundversuche der Physic in hhistorischer Darstellung and his founding of the periodical Physikalische Blätter.

In order to pursue research on the ballistics problem treated in his doctoral dissertation. Ramsauer joined the staff to the torpedo laboratory in Kiel. He also continued to deal with ballistics while at Danzig and Berlin. His most important work in this area concerned the explosive pressure impulse resulting from firing shells underwater and the firing of a moving rifle to maximize the pressure impulse.

While at the Heidelberg institute, Ramsauer became acquainted with Lenard’s methods and research interests. In 1913 he published an account of what is now called the Ramsauer circular method, which allowed him to ascertain with a high degree of precision the velocity, and thus the energy, of slow electrons, which he had obtained through use of the photoelectric effect. The electrons were forced into circular paths in a uniform magnetic field, separated out by means of suitably mounted diaphragms, and directed toward a collector connected to an electrometer. In this way the number of electrons arriving during each second could be determined exactly. After World War I, Ramsauer used this apparatus to discover the effect named for him.

Initially, Ramsauer studied the absorption in gases of electrons with steadily decreasing velocity. The results at first confirmed expectations; the penetrability of the gas atoms decreased. But at velocities corresponding to one electron volt(EV) the penetrability of argon exhibited a striking increase, attaining a maximum at 0.5 EV–as if only 4 to 6 percent of its kinetic-theory cross section were operative. On this occasioin Ramsauer coined the term and the associated concept–“effective cross section” (Wirkungsquerschnitt), which became one of the most common technical terms in atomic and nuclear physics. Analogous findings were made for xenon and krypton; no reasonable explanation of the effect was possible at the time, however, for it is a consequence of the wave nature of the electron and could not be accounted for until the development of wave mechanics. Ramsauer subsequently collaborated with his students on extensive studies of other gases and ions that yielded a large number of findings. Although his work at the AEG left him little time for his own research, he was nevertheless able to attract outstanding coworkers and to consider a host of new problems. The most important project with which he was associated during these years was the development of an electron microscope with electrostatic lenses.

BIBLIOGRAPHY

I. Original Works. An early work of Ramsauer’s is “Über eine direkte,” magnetische Methode zur Bestimmung der lichtelektrischen Geschwindigkeitsverteilung,” in Annalen der physik 4th (1914), 961–1002. On the Ramsauer effect, see “Über den Wirtungsquerschnitt der Gasmoleküle gegenüber langsamen Elektronen,” ibid., 64 (1921), 513–540; and 66 (1921),546–558; and Wirkungsquerschnitt der Edelgase gegenüber langsamen Elektronen, Ostwald’ s Klassiker der Exacten Wissenschaften, no.245 (Leipzig,1954), written with R.Kollath. See also “Negative und positive Strahlen,” in H. Geiger and K.Scheel,eds., Handbuch der physik XXII, pt, 2(Berlin, 1933), 243–310, written with R.Kollath Later writings are physik pädagogik Technik (Karlsruhe, 1949); and Grundversuche der physik in historischer Darstellung (Berlin,1953). A complete bibliography of Ramsauer’s works is in Poggendorff, V,1020; VI, pt. 3,2116; and VIIa, 668–669.

II. Secondary Literature. On Ramsauer and his work, see(listed chronologically) O.Eisenhuyt, “Zum 60. Geburtstag,” in Zeitschrift für technische physik20 (1939) 33–36, with portrait; and E.Brüche, “Zum 70. Geburstag,” in Physikalische Blättebr 5 (1949), 51–53, with portrait; and “Nekrolog,” ibid12 (1956), 49–54, with portrait.

F. Fraunberger

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Ramsauer, Carl Wilhelm

RAMSAUER, CARL WILHELM

(b. Osternburg, Oldenburg, Germany, 6 February 1879; d. Berlin, Germany, 24 December 1955)

physics.

For a detailed study of his life and work, see Supplement.

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"Ramsauer, Carl Wilhelm." Complete Dictionary of Scientific Biography. . Encyclopedia.com. 21 Aug. 2017 <http://www.encyclopedia.com>.

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"Ramsauer, Carl Wilhelm." Complete Dictionary of Scientific Biography. . Retrieved August 21, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/ramsauer-carl-wilhelm-0