History of the RIKEN cyclotron

The first cyclotron in Japan was build by Dr. Nishina at RIKEN in 1937 and was used for pioneering studies on nuclear physics, nuclear chemistry, and biology. After seven years, in 1944, a large cyclotron was constructed also by Dr. Nishina. Unfortunately, it was destroyed mistakenly the occupation forces immediately after World War II; however, the pioneering spirits was never defeated. Followed by a small cyclotron rebuilt in 1952, a 160-cm cyclotron was constructed in 1966, which accelerated not only light ions but also heavy ions of various elements.

The heavy ion provide a unique opportunity for studies in a variety of field including unclear physics, atomic physics, solid state physics, nuclear chemistry, material engineering, radiation chemistry, and radiation biology. Though the work performed at the cyclotron, accelerated heavy ions are recognized to be a versatile tool for many fields and, therefore, a new-generation accelerator has been demanded.

The world's first variable-frequency linear accelerator(RILAC) has been in operation since 1980. the RILAC accelerates all ions in the periodic table to an energy of 4 MeV/nucleon for light ions and 0.8 MeV/nucleon for heavy ions. The RILAC also acts as an injector for the higher-energy RIKEN ring cyclotron (RRC), which stated to deliver beam of heavy ions in late 1986.

1st cyclotron

Magnet diameter 65 cm. The first cyclotron in Japan. Completed 1937.

2nd cyclotron

Magnet diameter 150 cm. Completed 1943.

3rd cyclotron

Magnet diameter 65 cm. Completed 1953.

4th cyclotron

Magnet diameter 210 cm. Completed 1966.

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last updated on 25 Oct 1996 by T.Ichihara (www-admin@rikvax.riken.go.jp)