Asked to vet Nishina by US intelligence officers, Kelly took the file home and made his assessment: “He was an international scholar, respected all over the world. And he had spoken out against the war. I said it was against everyone's interests to purge that man." Nishina sought to restart Japanese science after the war and found an ally in Kelly. Two issues were most important for Nishina: acquiring radio isotopes for research for a variety of nonmilitary purposes and attempting to preserve Riken as an institution for scientific research, which occupation forces were seeking to dismantle on the basis of anti-monopoly concerns. Riken owned stocks of some large companies. When an interim agreement was worked out, Nishina became head of the reorganized Riken. Nishina died from liver cancer in 1951. Since Nishina's widow was ailing herself, help with care of Nishina's children (Yuichiro and Kojiro) came from Nishina's assistant at Riken, Sumi Yokoyama. Harry Kelly, his friend and colleague, remained close to the family after Nishina's death. Kelly's ashes were buried in a grave besides Nishina's in Tama Cemetery in Tokyo in a ceremony attended by Nishina's and Kelly's families. Work Nishina co-authored the Klein–Nishina formula. 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), and narrowly missed out on the discovery of the first transuranic element, neptunium. 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. See also Nishina Memorial Prize Nishina, a crater on the Moon named in Nishina's honor. References 1890 births 1951 deaths Hibakusha Japanese nuclear physicists Japanese physicists Recipients of the Order of Culture University of Tokyo alumni People from Okayama Prefecture Deaths from liver cancer Riken personnel