Element 99

According to the Physical Review, a group of scientists at the University of California (Albert Ghiorso, G. Bernard Rossi, Bernard G. Harvey and Stanley G. Thompson) have created Element 99, the heaviest so far. They did it by bombarding Uranium 238 (Element 92) with a beam of positively charged nitrogen atoms from a 60-inch cyclotron. The nitrogen atoms contained seven protons and seven neutrons, and when they collided with U-238, all except five of the neutrons joined its nucleus. The seven added protons raised the atomic number to 99, and the added neutrons and protons together raised its atomic weight to 247.

Element 99 is not long-lived; half of it disintegrates in 7.3 minutes. It is not plentiful. Only 40 atoms of it were identified. Their total weight: less than six hundred-trillion-trillionths of an ounce.

The work was done under the Atomic Energy Commission, which is pushing similar work with beams of nitrogen and other large nuclei in many parts of the U.S. The AEC's long-range interest can be guessed at. When a nitrogen atom can be made to hit U-238, not normally considered fissionable, it almost always causes fission. When it forms Element 99, it liberates five free neutrons, and these are capable of causing fission too. AEC may be feeling for a new method of releasing atomic energy from difficult U-238.

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