Lew Kowarski

Lew Kowarski (10 February 1907, Saint Petersburg – 30 July 1979, Geneva) was a naturalized French physicist. He was a lesser known but important contributor to nuclear science.

Lew Kowarski was born in Saint Petersburg to Nicholas Kowarski, a businessman and the Ukrainian singer Olga Vlassenko. Following the Bolshevik Revolution, when Lew was 12 years old, his family fled west under adventurous circumstances and settled in Vilnius (then in Poland). During his youth, Lew was a talented musician and considered a music career; however, his fingers grew too large for the keyboard.

He received a Chemical Engineering degree from the University of Lyon and an Sc.B. and Ph.D. from the University of Paris where he carried out research on neutron counting.

He joined Frédéric Joliot-Curie's group in 1934, where Hans von Halban came in 1937. They established in 1939 the possibility of nuclear chain reactions and nuclear energy production. While doing their research, the events of World War II forced them to eventually move to England, bringing with them the world's entire stock of heavy water, given on loan by Norway to France so that it would not fall into German hands. They continued their research at the Cavendish Laboratory in Cambridge for the MAUD Committee, part of the wartime Tube Alloys project.

Just before the invasions, the records and papers of Frédéric Joliot, Hans Halban and Lew Kowarski were smuggled out of France, and eventually to England. Included in this operation were 26 drums of heavy water, the world’s entire stock at the time. Some of the papers written by Halban and Kowarski were deposited at the Royal Society in the UK, where they were sealed with a note from James Chadwick, dated December 18, 1941, that said, “The paper is such that it would be inadvisable to publish it at the present time.” The papers described the outline of a design for a nuclear fission reactor.

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