Bunsaku Arakatsu

was a Japanese physics professor in the World War II Japanese Atomic Energy Research Program of the Imperial Japanese Navy. Arakatsu was a former student of Albert Einstein.

Career

In 1928, Arakatsu became a professor at Taihoku Imperial University (now called National Taiwan University). In 1934 Arakatsu built a particle accelerator at Taihoku Imperial University in Taihoku, Formosa (now Taipei, Taiwan), and performed the first atomic nucleus collision experiment in Asia there, shortly after the experiment performed at the Cavendish Laboratory of the University of Cambridge. He reported that each nuclear fission of a U-235 atom yields, on average, 2.6 neutrons.

In 1936, he became a professor at Kyoto Imperial University (now called University of Kyoto).

In 1943, during World War II, he led the Japanese Naval research program into nuclear technology, known as the F-Go Project. Alongside Yoshio Nishina, Arakatsu was one of Japan's leading nuclear physicists. His team included Hideki Yukawa, who would become in 1949 the first Japanese physicist to receive a Nobel Prize.

Early on in the war Commander Kitagawa, head of the Navy Research Institute's Chemical Section, had requested Arakatsu to carry out work on the separation of Uranium-235. The work went slowly, but shortly before the end of the war he had designed an ultracentrifuge (to spin at 60,000 rpm) which he hoped would achieve the required results. Only the design of the machinery was completed before the Japanese surrender.

After the Americans atom bombed Hiroshima, he was transferred to Navy Minister Mitsumasa Yonai to form an investigative commission. This commission inspected the affected area to determine the effects of the bomb.

After the war, his reports and artifacts were largely destroyed or confiscated by the occupying GHQ, which brought much protest from Arakatsu and the international community. Whatever documents that had survived the purge are now kept in the Yamato Museum in Kure.