WASHINGTON, Aug. 2 Kyodo, The U.S. Library of Congress possesses notebooks containing memos by two Japanese scientists involved in Japan's unsuccessful attempt to develop atomic bombs during World War II, Kyodo News discovered recently.

The memos were written by Sakae Shimizu and Yoshiaki Uemura -- two of the scientists who worked at a laboratory led by Bunsaku Arakatsu, a professor at Kyoto Imperial University, currently Kyoto University, which was ordered by the Imperial Japanese Navy to develop atomic bombs, according to the two notebooks, copies of which were obtained by Kyodo News.

The notebooks were seized by the General Headquarters of the Allied Forces which occupied Japan after the war. They have been stored among a pile of wartime Japanese documents without being sorted and indexed to date at the library in the U.S. capital.

The memos date from before Japan began full-fledged development of atomic bombs. Such documents written by scientists involved in the front line of Japan's atomic bomb program are rare.

Discovered 61 years after the United States dropped the world's first atomic bomb on Hiroshima on Aug. 6, 1945, the notebooks are likely to become an important material for research on Japan's wartime atomic development program, about which much is still unknown.

According to research by Kyodo News and Keiichi Tsuneishi, a professor at Kanagawa University, the library has more than 10,000 wartime Japanese documents. They remain untouched without being catalogued.

Among them are the two notebooks -- one with about 220 pages of memos written by Shimizu and the other with about 75 pages of memos written by Uemura. They served under Arakatsu, who was asked by the navy to develop bombs based on atomic fission technology.

Shimizu, who later became a professor emeritus at Kyoto University, was involved in the production of a cyclotron, an accelerator used in researching nuclear reactions.

His notebook, titled ''Laboratory Notes 2,'' details the development of the high-voltage accelerator from 1942.

Shimizu, who died in 2003 at 88, visited Hiroshima soon after the U.S. atomic bombing as a member of an academic survey mission. He is known for his analysis of dust on Japanese fishing boat Fukuryu Maru No. 5 which led to the discovery that the vessel was exposed to radiation from a U.S. hydrogen bomb test in the Pacific archipelago of Bikini, part of the Marshall Islands, in 1954.

Uemura, who later became a professor at Kyoto University, wrote about basic research from 1941 in his notebook, titled ''Research Diary,'' including research on nuclear reactions when metal is exposed to gamma rays.

His memos also show that construction of a cyclotron was decided June 14, 1941, and that a comparison was made with the results of testing conducted by Danish physicist Niels Bohr, who had cooperated with the secret wartime U.S. atomic bomb development program called the Manhattan Project.

The U.S. effort succeeded in developing the world's first atomic bomb, leading to the first use of a nuclear weapon on Hiroshima and then on Nagasaki three days later.

Japanese scientists had recognized the potential of using atomic energy to develop a powerful new bomb even before World War II.

While the navy commissioned the Arakatsu laboratory to undertake research, the Imperial Japanese Army had ordered a laboratory led by Yoshio Nishina at Riken, a national research institute for physical and chemical sciences, to do likewise.

Both atomic programs failed, with the Arakatsu laboratory aiming at uranium enrichment through use of a centrifuge but unable to produce the devise before the end of the war.

2006-08-03 10:05:15JST