Meitner, Lise, 1878-1968, Austrian-Swedish physicist and mathematician. She was professor at the Univ. of Berlin (1926-33). A refugee from Germany after 1938, she became associated with the Univ. of Stockholm and with the Nobel Institute at Stockholm. In 1917, working with Otto Hahn, she isolated the most stable isotope of the element protactinium; she also investigated the disintegration products of radium, thorium, and actinium and the behavior of beta rays. In 1938 she participated in experimental research in bombarding the uranium nucleus with slow-speed neutrons. Meitner interpreted the results as a fission of the nucleus and calculated that vast amounts of energy were liberated. Her conclusion contributed to the development of the atomic bomb. In 1949, she became a Swedish citizen. The element with the atomic number 109 is named meitnerium in her honor.

(born Nov. 7, 1878, Vienna, Austria—died Oct. 27, 1968, Cambridge, Cambridgeshire, Eng.) German physicist. She worked at Berlin's Kaiser Wilhelm Institute (1912–38), also teaching at the University of Berlin (1926–38). At a laboratory that she set up with Otto Hahn, the two isolated the radioactive isotope protactinium-231. In the 1930s, with Hahn and Fritz Strassmann (1902–80), she investigated the products of neutron bombardment of uranium. She left Germany in 1938 for Sweden. After Hahn and Strassmann demonstrated that barium appears in neutron-bombarded uranium, she and her nephew Otto Frisch (1904–79) explained the physical characteristics of this division and in 1939 proposed the term fission for the process. She shared the 1966 Enrico Fermi Award with Hahn and Strassmann. Element 109, meitnerium, is named in her honour.

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Meitner may mean or relate to:

• Lise Meitner (1878 - 1968), Austrian nuclear physicist
• Meitner (lunar crater)
• Meitner crater, a multiring impact basin on Venus
• Hahn-Meitner Institute, scientific research institute in Berlin
• Meitner–Hupfeld effect, particle physics phenomenon