107 BOHRIUM Bh (Neils Bohr, Danish physicist) [Neilsbohrium Ns]

An artificially produced, highly unstable, transuranic element with no detectable natural occurrence on Earth. Alpha-alpha correlation, in which the alpha decay of the unknown isotope and that of its alpha decay products are correlated in time, can be used to positively identify short lived isotopes and was used by Peter Armbruster at the Heavy Ion research centre at GSI in Germany to identify bohrium. Bohrium was reported to have been made in 1976 by bombarding a target of bismuth-209 with accelerated chromium-54 nuclei, which then decayed by alpha emission. Currently, two isotopes of element 107 are known, bohrium-261 and -262 with halflives of only milliseconds. It is postulated that if more neutron rich isotopes can be formed with about 162 neutrons, a new region of stability, they may well have longer halflives. Nuclear reactions using berkelium-249 or einsteinium-254 targets with neon or oxygen projectiles have been suggested for some time to reach the heavier, neutron-rich isotopes of bohrium and meitnerium near the region of extra stability, but has never been funded because of enormous cost. It was only named bohrium in 1993.

Recently, in December 1994, bohrium-264 was briefly observed by the team at GSI, Darmstadt, which originated from the alpha decay chain of element 111-272 via 109-268.

The isotope with the longest known halflife of bohrium is bohrium-262 with a very short halflife of just 115 milliseconds decaying by alpha decay into the alpha/electron capture decaying hahnium-258 which has a halflife of 4.4 seconds.

Altogether, just 3 isotopes of bohrium are known, all radioactive, and ranging from the alpha/spontaneous fission decaying bohrium-261 which has a halflife of just 1.2 milliseconds to the alpha decaying bohrium-264.

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