Yoshio Nishina

Who was Yoshio Nishina?

Yoshio Nishina was the founding father of modern physics research in Japan. He co-authored the well-known Klein–Nishina formula. He was a principal investigator of RIKEN and mentored generations of physicists, including two Nobel Laureates: Hideki Yukawa and Sin-Itiro Tomonaga. During World War II he was the head of the Japanese nuclear weapon program. The crater Nishina on the Moon is named in his honor.

Nishina was born in Satoshō, Okayama and graduated from Tokyo Imperial University in 1918. After graduation, he became a staff member at the Institute of Physical and Chemical Research. In 1921 he was sent to Europe for research. He visited some European universities and institutions, including Cavendish Laboratory, Georg August University of Göttingen, and University of Copenhagen. In Copenhagen he did research with Niels Bohr and they became good friends. In 1928 he wrote a paper on incoherent or Compton scattering with Oskar Klein in Copenhagen, from which the Klein–Nishina formula derives.

In 1929 he returned to Japan, where he endeavored to foster an environment for the study of quantum mechanics. He established Nishina Laboratory at the Institute of Physical and Chemical Research in 1931 and invited some Western scholars to Japan including Heisenberg, Dirac and Bohr to stimulate Japanese physicists. His research was concerned with cosmic rays and particle accelerator development for which he constructed a few cyclotrons at RIKEN. In particular, he detected what turned out to be the muon in cosmic rays, independently of Anderson et al. He also discovered the uranium-237 isotope and pioneered the studies of symmetric fission phenomena occurring upon fast neutron irradiation of uranium. His laboratory was severely damaged during World War II and most equipment had to be discarded and rebuilt after the war.