NISHINA, YOSHIO

(b. Okayama, Japan, 6 December 1890; d. Tokyo, Japan, 10 January 1951)

physics, nuclear physics.

Yoshio was the sixth son of Tsune and Arimasa Nishina. They had seven sons and two daughters. Arimasa was a rich landowner engaged in agriculture and salt making. Tsune used to make her children arrange such family events as travels and birthday parties. Yoshio’s grandfather Arimoto had been famous for his handling of the finances of Aoki-fun, a feudal clan in the area. Yoshio was known as a bright boy of strong physical health and a warm heart. He liked such sports as tennis and boat racing.

After receiving his education through high school in Okayama, Nishina entered the College of Engineering at the University of Tokyo, where he majored in electrical engineering. In 1918 Nishina graduated as valedictorian, for which he received the Taisho emperor’s celebrated silver watch. Having been stimulated by reading Einstein and others, Nishina went to the graduate school of the university, where he majored in physics. From 1918 to 1920 Nishina attended lectures by Hantaro Nagaoka, known for his Saturnian atomic model, and he became a Nagaoka disciple. In 1918 Nishina became a research associate at the Institute of Physical and Chemical Research (Riken), which had been established in 1917 with the financial support of the Japanese government and business interests. The institute sent him abroad (to England, Germany, Denmark) for advanced study from 1921 to 1928.

After completing the Klein-Nishina formula in Copenhagen, Nishina returned to Japan at the end of 1928 and started to work at Riken again. Nishina was invited by Kyoto University to deliver special lectures on quantum mechanics in May 1931. His lectures, which were based on Werner Heisenberg’s book Die physikalischen Prinzipien der Quantentheorie (1930), were attended with great interest by young physics students, including Hideki Yukawa and Shinitiro Tomonaga (Nobel Prize winners in 1949 and 1965), Shoichi Sakata, and Minoru Kobayashi. From 1931 Nishina managed his own laboratory at Riken, Nishina Laboratory, which became the most important center for theoretical and experimental nuclear physics in Japan before World War II. The first generation of the Elementary Particle Theory Group of Japan was trained by Nishina.

During and after World War II Nishina played an important role as science administrator rather than research physicist. He became the president of Riken in 1946 and the vice chairperson of the Japan Science Council in 1949. Nishina was hospitalized with liver cancer just before his sixtieth birthday, and he died the following year. He was awarded the Order of Cultural Merit of Japan in 1946. Nishina had married Mie in 1929; they had two sons.

The development of physics based on quantum mechanics in Japan was greatly enhanced by what Nishina had learned in Europe. From the fall of 1921 Nishina studied experimental physics for about one year under Lord Rutherford at the Cavendish Laboratory at Cambridge University. His topic was experimental analysis on the X rays scattered by electrons. From the winter of 1922 to the spring of 1923 Nishina studied theoretical physics by attending lectures by Max Born and David Hilbert at Göttingen University. From the spring of 1923 to the fall of 1928 he remained mostly in Copenhagen. These years were a time of significant development in quantum mechanics. Nishina worked at the Institute for Theoretical Physics under Niels Bohr, around whom gathered such physicists as Hendrik Kramers, Werner Heisenberg, Wolfgang Pauli, Pascual Jordan, Oskar Klein, and Paul Dirac.

While at the Bohr Institute, Nishina published his first paper, which aimed to give experimental evidence for Bohr’s atomic theory. Nishina was very interested in quantitative chemical analysis by means of X-ray spectra. He brought this approach back to Japan with him. In 1927 he published a paper in Zeitschrift für Physik with two Japanese chemists, Shinichi Aoyama and Kenji Kimura, who were also in Copenhagen. From Copenhagen Nishina went to Paris in the summer of 1927, and then visited Wolfgang Pauli at Hamburg University, where he met Isidor Rabi, an American physicist born in Austria. They worked together and became very good friends.

In early 1928 Nishina returned to Copenhagen and worked with Oskar Klein. As a result of their cooperation, the Klein-Nishina formula was completed in October of the same year, before Nishina’s return to Japan. In 1923 the quantum (particle) nature of X rays was discovered by Arthur Compton. Nishina had once made an experimental approach to this phenomena at the Cavendish Laboratory. The relation among the increased wavelength of the scattered X rays, the energy of recoiled electrons, and the scattering angle was accounted for by the quantum nature. In 1928 Nishina and Klein calculated the cross section and intensity of the Compton scattered radiation by the use of Dirac’s new relativistic quantum mechanics of electrons. They succeeded in a complicated calculation by doing this separately and checking it together. (Nishina also brought this method of calculation with a team back to Japan.)

Nishina and Klein searched for the solution of Dirac’s wave equation in the case of a free electron (initially at rest) in the field of a plane electromagnetic wave. For the intensity I of the Compton scattered radiation at a distance r and in a direction making an angle with the normal to the primary wave, they obtained the following expression:

where ζ is the angle between the observed direction and electric vector in the primary wave

Their result differed from the earlier relativistic quantum mechanics of Dirac and Gordon by the order α², while the difference between the quantum theory and classical theory had been on the order of α. The wavelength of cosmic rays that had been estimated by Dirac-Gordon called for a modification. The new result was brought to the attention of the Russian physicist Dmitri Skobelzyn, who began a scientific correspondence with Nishina.

As a continuing part of their work, Nishina and Klein calculated the polarization of Compton scattered radiation on the Dirac theory with the help of a young Danish physics student, Christian Möller. Their results were published in 1929. Pauli published results of similar work, that is, the calculation of the intensity of the scattered radiation in the case of a “moving” electron, in 1933. The Klein-Nishina formula played an important role in discussions of the applicable limits of quantum mechanics to studies of cosmic rays and nuclear physics.

In late 1928 Nishina returned to Japan with a number of useful experiences, including his close observation of the process of development in quantum mechanics and his direct participation in this development. He was particularly impressed by the productive and open-minded atmosphere among various physicists at the Bohr Institute. This so-called “Copenhagen spirit” was brought back to Japan with Nishina. One his brightest followers, Hideki Yukawa, described this “spirit” in his 1958 autobiography:

If I were asked to describe the spirit of Copenhagen, I would not be able to do so in a few words. However, it is certain that it had much in common with the spirit of generosity. Having been liberally educated, I was especially attracted by that, but I was also attracted by Dr. Nishina himself. I could talk to him easily, although I was usually very quiet. Perhaps I recognized in Nishina the kindly father figure that I could not find in my own father. Whatever it was, my solitary mind, or my closed mind, it began to open in the presence of Dr. Nishina (Tabibito, The Traveler [Singapore, 1982], 177).

Through his long experiences in Europe, Nishina was convinced that an intimate contact between theory and experimentation was necessary to carry out creative research in physics. This is the approach followed by the research program on nuclear physics at Nishina Laboratory from its birth in 1931. In the field of experimentation, Ryokichi Sagane, the fifth son of Hantaro Nagaoka, and Masa Takeuchi, new graduates from the University of Tokyo, began to construct such instruments as Geiger-Müller counters and Wilson cloud chambers. By means of Geiger-Müller counters, measurements of cosmic rays, in Shimizu tunnel for example, were carried out by members of the experimental physicists group. Investigations of tracks of cosmic rays were made by the use of a large-scale cloud chamber (40 centimeters in diameter placed in a uniform magnetic field 10, 000 gauss in intensity). They succeeded in distinguishing between proton tracks and those of meson, which had been predicted by Hideki Yukawa in 1935. The paper by Nishina, Takeuchi, and Torao Ichimiya was published right after the famous one by Carl Anderson and Seth H. Neddermeyer in 1937.

In the field of theory, Shinitiro Tomonaga and Shoichi Sakata, graduates of Kyoto University, began to calculate the process of positron-electron pair creation by the use of Dirac’s 1933 electron theory. In 1934 Minoru Kobayashi, a classmate of Sakata’s (who went to Osaka to become Hideki Yukawa’s assistant) and Hidehiko Tamaki, a new graduate from the University of Tokyo, joined this group. In the summer of 1935 in Karuizawa (a famous summer resort in Japan) they worked together to translate the newly published second edition of Dirac’s book, The Principles of Quantum Mechanics, into Japanese. Their translation, published in 1936, played an important role among young physicists and students. At the recommendation of Nishina, Tomonaga was sent from Riken to Germany to work under Werner Heisenberg at Leipzig University from 1937 to 1939. Tomonaga later developed his famous “super-many-time” theory.

The first cyclotron in Japan was constructed by members of Nishina Laboratory between 1935 and 1937. For this construction Riken collected donations from Japanese business circles totaling about $3 million between 1936 and 1937. The Mitsui-funded foundation Mitsui Hōonkai, established in 1933, offered about $150, 000 for the buildings. The main part of the machine was contributed by the Japan Wireless Telegraph Company, established with government funds in 1925. The running costs were covered by an endowment of $100, 000 from the Tokyo Electric Light Company (Toshiba).

Nishina’s followers noticed that his attitude toward journalists and the general public changed rapidly around this time. In his public lectures he tried to emphasize how studies in experimental nuclear physics are useful for people’s daily lives. He also wrote a number of articles in popular science journals. These activities, Nishina thought, were crucial to the fundraising effort.

Nishina considered the first small cyclotron to be preliminary to a larger one like Ernest Lawrence’s cyclotron at Berkeley, California. From 1938 Ryokichi Sagane and others at the Nishina Laboratory began to construct a sixty-inch cyclotron with a two-hundred-ton magnet. The main parts of this cyclotron were obtained from the United States with Lawrence’s help. Construction of the larger cyclotron was more difficult than the smaller one. Sagane and others visited Lawrence to receive his technical advice on details. Their efforts are evident in their correspondence with Lawrence (carton no.9, file no. 38, Bancroft Library, University of California, Berkeley). But despite their efforts, the cyclotron remained uncompleted and was destroyed by the American military, owing to a misunderstanding in 1945. This experience helped Nishina to recognize the deep technological gap between Japan and the U.S.

Nishina was never appointed professor at national universities such as the University of Tokyo and Kyoto University. This was due to his having graduated from a college of “engineering” rather than “science”. It was through the Institute of Physical and Chemical Research that Nishina established himself as the founder of nuclear physics in Japan. Because of Riken, Nishina was allowed to spend more years abroad than professors at national universities, who used to return after only two or three years. As part of Riken, the Nishina Laboratory rapidly increased its space, personnel, and budget from 1931 to the end of World War II. Nishina had the great fortune of developing such genius followers as the Nobelists Hideki Yukawa and Shinitiro Tomonaga. Without Nishina’s return from Europe with the principles of quantum mechanics, these two physicists might never have developed their potentials to the fullest.

BIBLIOGRAPHY

I. Original Works. Nishina’s principal papers include “Röntgenspectroskopie. Über die Absorptionsspektren in der L-Serie der Element La (57) bis Hf (72),”, in Zeitschrift für Physik, 18 (1923), 207–211, written with D. Coster and S. Werner; “On the L-absorption Spectra of the Elements from Sn (50) to W(74) and Their Relation to the Atomic Constitution,” in Philosophical Magazine, 49 (1925), 521–537; “Die Abhängigkeit der Röntgenabsorptionsspekren von der chemischen Bindung”, in Zeitschrift für Physik, 44 (1927), 810–833, written with S. Aoyama and K. Kimura; “Über die Streuung von Strahlung durch freie Elektonen nach der neuen relativistischen Quantendynamik von Dirac”, ibid., 52 (1929), 853–868, written with O. Klein; “Die Polarisation der Comptonstreuung nach der Diracschen Theorie des Elecktrons”, ibid., 869–877; “A Note on the Interaction of the Neutron and the Proton,” in Scientific Papers of the Institute of Physical and Chemical Research, 30 (1936), 61–69, written with S. Tomonaga and H. Tamaki; “On the Nature of Cosmic-Ray Particles”, in Physical Review, 52 (1937), 1198–1199, written with M. Takeuchi and T. Ichimiya.

The Nishina Kinen Zaidan owns Nishina’s books and manuscripts and has published George Hevesy-Y. Nishina, Correspondence 1928–1949 (Tokyo, 1983). They are planning to publish a biography of Nishina. H. Tamaki and other members of the Zaidan have been reporting results of their research to the History of Physics Section at the annual meetings of the Physical Society of Japan. The address of the Zaidan is 2–28–45 Motokomagome, Bunkyoku, Tokyo 113, Japan.

II. Secondary LiteratureNishina Yoshio denki to kaisō, S. Tomonaga and H. Tamaki, eds., (Tokyo, 1952) includes an outline of Nishina’s life and work by Fumio Yamazaki, Nishina’s essays from 1949 and 1950, and reminiscences by H. Yukawa, S. Tomonaga, H. Tamaki, S. Sakata, and others. Cosmic ray studies at the Nishina Laboratory are discussed in M. Takeuchi, Yataro Sekido, and Harry Elliot, eds., Early History of Cosmic Ray Studies (Dordrecht and Boston, 1985). The academic and social backgrounds of physics in Japan are discussed in Nakayama Shigeru, David L. Swain, and Yagi Eri, eds., Science and Society in Modern Japan (Cambridge, Mass., 1974) and the Physical Society of Japan, ed., Nihon no Butsurigakushi (“One Hundred Years of Physics in Japan”), 2 vols. (Tokyo, 1978).

Eri Yagi