Riken stands for "Rikagaku Kenkyuudjyo" (理化学研究所, Physics and Chemistry Research Place), a Japanese research entity of "natural sciences" (Physics, Biology, Chemistry etc.) It is composed of several institutes, spread on many provinces in Japan. Amongst many achievements, they are well known for their researches on atomic structure, using the RI Beam Science Laboratory cyclotron, which led to the creation of the heaviest hydrogen isotopes known, hydrogen-5 (5H, in 2001) and hydrogen-7 (7H, in 2003), gathering Japanese, Russian and French researchers. Many believe that 5H are common in extreme conditions, like those found in heavy stars, awaiting confirmation by astronomical observations.
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