November 17, 1941 – Japanese physicist Yoshio Nishina reported to his army liaison officer Major General Nobuji that the atomic bomb research project under him had not made much progress in the past nine months. This was partly because his cyclotron could not operate at full power due to the poor quality vacuum tubes. 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. 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 (1939–1940). His laboratory was severely damaged during World War II and most equipment had to be discarded and rebuilt after the war.