Nishina file photo [11316]

Yoshio Nishina

Given NameYoshio
Born6 Dec 1890
Died10 Jan 1951


ww2dbaseYoshio Nishina was born in Satosho, Okayama, Japan. He graduated from the Tokyo Imperial University in 1918. In 1921, he was sent to Europe for research; during his time in Europe, he visited the Cavendish Laboratory, Georg August University of Göttingen, and University of Copenhagen. At Copenhagen, he did research with Niels Bohr, who had won the Nobel Prize in Physics in 1922 for his atomic research, and became good friends. In 1928, Nishina and Oskar Klein wrote a paper on incoherent or Compton scattering, from which the Klein-Nishina formula came about. He returned to Japan in late 1928 and attempted to generate interest in quantum physics in Japan. To that end he established a nuclear research laboratory in Tokyo in 1931 as a part of the Institute for Physical and Chemical Research, also known as the Riken Institute. During the 1930s, he focused his research on cosmic rays and the development of particle accelerators, completing his first cyclotron in 1936 and then a larger one in 1937.

ww2dbaseIn 1939, as Japan had already been involved in war for several years, Nishina recognized the military potential of nuclear fission, as many physicists were beginning to at that time. In the early summer of 1940, he met with Lieutenant General Takeo Yasuda, director of the Technical Research Institute of the Japanese Army Aeronautical Department, on a train, and discussed with him the possibility of nuclear weapons. In Apr 1941, Prime Minister Hideki Tojo ordered Yasuda to explore that possibility, who in turn passed the order down to director of Riken Okochi Masatoshi, knowing that it would fall on the desk of Nishina, who by that time had over 100 physicists working for at his laboratory. With this order from Tojo, Nishina became the chairman of the Committee on Research in the Application of Nuclear Physics, which was to include the Japanese Navy's fledging nuclear weapons research program as well. Although his researchers made advances, he thought that to actually produce a practical weapon within a few years was unlikely, "even for the United States". This comment discouraged the Japanese Navy, which redirected its scientific efforts toward radar instead, but the Army continued on with Nishina's team. In Jul 1943, his Army liaison, Major General Nobuji, met with him and promised funding for him to complete a large 60-inch cyclotron. Although this larger cyclotron was completed, the vacuum tubes used were of inferior quality due to the war situation, and as a result by summer of 1944 Nishina's team was only able to produce 170 grams of uranium hexafuoride; by this time, his counterparts in the United States had already produced it by the ton. The research was ultimately fruitless.

ww2dbaseAfter the war on 16 Oct 1945, Nishina sought permission from the American occupation administration to use his two cyclotrons for biological and medical research. The request was initially granted, but on 10 Nov the United States Secretary of War Robert Patterson ordered all cyclotrons in Japan destroyed, which was done on 24 Nov. He wrote a letter of protest, noting his cyclotrons had nothing to do with weapons research despite them being a part of the Japanese Army's research program, Ni-Go, during the war; he argued that the involvement was simply for the funding so that he could continue his non-military research projects. On 3 Nov 1946, he was awarded the Order of Culture by Emperor Showa.

ww2dbaseSource: Wikipedia.

Last Major Revision: Oct 2010

Yoshio Nishina Timeline

6 Dec 1890 Yoshio Nishina was born.
2 Jul 1943 Japanese physicist Yoshio Nishina met his with army liaison officer Major General Nobuji and reported that he expected to be successful with the nuclear research project. He noted that 10 kilograms of uranium-235 of at least 50% purity to create an atomic bomb, but he needed a large cyclotron to conduct experiments to confirm this theory. Nobuji promised further funding.
17 Nov 1944 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.
16 Oct 1945 Japanese physicist Yoshio Nishina sought permission from the American occupation administration to use his two cyclotrons for biological and medical research. The request was granted, but orders from United States Secretary of War Robert Patterson dated 10 Nov would have all cyclotrons in Japan destroyed on 24 Nov.
3 Nov 1946 Yoshio Nishina was awarded the Order of Culture by Emperor Showa.
10 Jan 1951 Yoshio Nishina passed away.


Physicists Yoshio Nishina, Llewellyn Thomas, and Friedrich Hund in Copenhagen, Denmark, 1926Portrait of Japanese physicist Yoshio Nishina, date unknown

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Visitor Submitted Comments

1. Anonymous says:
15 Oct 2014 05:15:16 AM

Exact translation of the TONIZO reports. Meeting on Uranium research at the Nishina Laboratory 6th July 1943. Critical mass of U235 estimated at 10 Kg with reflector. [There is no mention of 50% enrichment.] The State of Uranium Research at the Nishina Laboratory 2 17th Nov. 1944. The result of the measurements (nuclear parameters) will reveal whether 10 Kg is enough or 20 Kg, or even 50 Kg is necessary. There is not much difference in the quantity between 0.7% and 10% but it will become vastly different if it is over 50% (enrichment).

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Physicists Yoshio Nishina, Llewellyn Thomas, and Friedrich Hund in Copenhagen, Denmark, 1926
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