was a Japanese

nuclear physicist Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter. Nuclear physics should not be confused with atomic physics, which studies the ...

who worked in France. She was the first Japanese female physicist.

Early life and education

Yuasa was born in

Taitō is a special ward in the Tokyo Metropolis in Japan. In English, it is known as Taitō City. As of May 1, 2015, the ward has an estimated population of 186,276, and a population density of 18,420 persons per km2. The total area is . This ...

Ward, Tokyo, in 1909. Her father was an engineer who worked for the Japanese patent office. Her mother was from a traditional literary family – her mother's grandfather was Tachibana Moribe. Toshiko was the second-youngest of seven children. She attended the Division of Science at Tokyo Women's Higher Normal School (now Ochanomizu University) from 1927 until her graduation in 1931. She then enrolled in the Department of Physics at Tokyo Bunrika University (now the

University of Tsukuba is a List of national universities in Japan, national research university located in Tsukuba, Ibaraki Prefecture, Ibaraki, Japan. The university has 28 college clusters and schools with around 16,500 students (as of 2014). The main Tsukuba ca ...

), making her the first woman in Japan to study physics. She graduated in 1934.

Career

Yuasa began teaching at Tokyo Bunrika University as a part-time vice-assistant after graduating in 1934. There, she began her research into molecular

spectroscopy Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectro ...

. In 1935 she became a lecturer at Tokyo Women's Christian College, where she remained until 1937. The following year, she was hired as an assistant professor at Tokyo Women's Higher Normal School. Yuasa was inspired by the discovery of artificial

radioactivity Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

by Irène and

Frédéric Joliot-Curie Jean Frédéric Joliot-Curie (; ; 19 March 1900 – 14 August 1958) was a French chemist and physicist who received the 1935 Nobel Prize in Chemistry with his wife, Irène Joliot-Curie, for their discovery of induced radioactivity. They were t ...

at the Radium Institute in Paris. Because of difficult research conditions in Tokyo, Yuasa moved to Paris in 1940, even though the Second World War had just begun in Europe. She worked under Frédéric Joliot-Curie at the

Collège de France The (), formerly known as the or as the ''Collège impérial'' founded in 1530 by François I, is a higher education and research establishment () in France. It is located in Paris near La Sorbonne. The has been considered to be France's most ...

, where she researched the

alpha Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ...

and

beta particle A beta particle, also called beta ray or beta radiation (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus, known as beta decay. There are two forms of beta decay, β− decay and � ...

s emitted by artificial radioactive nuclei and the energy spectrum of beta particles. With her thesis, titled "Contribution à l'étude du spectre continu des rayons β⁻ émis par les corps radioactifs artificiels" (Continuous beta-ray spectrum generated by artificial radioactivity), she earned a doctorate in science in 1943. With the Allied armies approaching Paris in August 1944, as a citizen of a country allied to Germany, Yuasa was urged to leave Paris. She continued her research in a laboratory at the

University of Berlin The Humboldt University of Berlin (, abbreviated HU Berlin) is a public research university in the central borough of Mitte in Berlin, Germany. The university was established by Frederick William III on the initiative of Wilhelm von Humbol ...

and developed her own beta-ray spectrometer. In 1945, she was ordered by Soviet officials to return to Japan; she travelled with her spectrometer carried on her back. Upon her return to Tokyo, she returned again to Tokyo Women's Higher Normal School as a professor. She was unable to continue her previous research, however, since the United States Occupation Forces prohibited nuclear research in Japan. From 1946 to 1949, she worked at the

RIKEN is a national scientific research institute in Japan. Founded in 1917, it now has about 3,000 scientists on seven campuses across Japan, including the main site at Wakō, Saitama, Wakō, Saitama Prefecture, on the outskirts of Tokyo. Riken is a ...

Nishina Center for Accelerator-Based Science and lectured at

Kyoto University , or , is a National university, national research university in Kyoto, Japan. Founded in 1897, it is one of the former Imperial Universities and the second oldest university in Japan. The university has ten undergraduate faculties, eighteen gra ...

in 1948–1949. Yuasa returned to France in May 1949 as a researcher for the

Centre national de la recherche scientifique The French National Centre for Scientific Research (, , CNRS) is the French state research organisation and is the largest fundamental science agency in Europe. In 2016, it employed 31,637 staff, including 11,137 tenured researchers, 13,415 eng ...

(CNRS) while remaining a professor-on-leave at Ochanomizu University. She decided to stay in France permanently in 1955, resigning from her post at Ochanomizu. At the CNRS, she began research into

beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which an atomic nucleus emits a beta particle (fast energetic electron or positron), transforming into an isobar of that nuclide. For example, beta decay of a neutron ...

using a Wilson chamber, and published a 1954 article warning of the dangers of hydrogen-bomb testing at Bikini Atoll. She was promoted to ''maître de recherche'' (chief researcher) at CNRS in 1957. Her research shifted into

nuclear reaction In nuclear physics and nuclear chemistry, a nuclear reaction is a process in which two atomic nucleus, nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides. Thus, a nuclear reaction must cause a t ...

s using synchrocyclotrons around 1960, and in 1962 she received a doctorate in science from Kyoto University for her thesis, "Étude du type d’invariant de l’interaction Gamow-Teller en désintégration β⁻ de ⁶He" (Form of Gamow-Teller invariant interaction on beta decay of ⁶He).

Retirement, death and legacy

Yuasa retired from the CNRS in 1974, but remained an emeritus researcher from 1975 onward. She received a Medal with Purple Ribbon from the Japanese government in 1976 for her efforts to promote cultural exchanges between France and Japan. She was hospitalised in January 1980 at the in Rouen. She died from cancer on 1 February 1980, aged 70. Yuasa was posthumously conferred the Order of the Precious Crown of the Third Class in 1980. Ochanomizu University introduced the Toshiko Yuasa Prize in 2002, a sponsorship for young women scientists to travel to France for further study.

References

{{DEFAULTSORT:Yuasa, Toshiko 1909 births 1980 deaths 20th-century Japanese physicists Ochanomizu University alumni Academic staff of Ochanomizu University Japanese nuclear physicists Japanese women physicists 20th-century Japanese women scientists Japanese expatriates in France People from Taitō French National Centre for Scientific Research scientists Women nuclear physicists Scientists from Tokyo