COULD a superheavy element, more massive than any created in the lab, really have gone unnoticed in Earth鈥檚 rocks until now? That was the claim of a team of physicists last week, but the announcement has prompted only scepticism.
Amnon Marinov at the Hebrew University of Jerusalem in Israel led a team that ran a purified solution of naturally occurring thorium through a mass spectrometer to measure the mass of individual atoms. Thorium has an atomic mass close to 232, but the team saw a handful of atoms with a much greater mass, at just over 292.
The heaviest atom hitherto known to occur in nature is an isotope of uranium: with 92 protons and 146 neutrons, its atomic mass is 238. Marinov thinks this putative new element contains either 122 protons with 170 neutrons, or possibly 124 protons with 168 neutrons ().
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If the team鈥檚 observations are correct, then the element must exist in nature, despite calculations which indicate that such atoms would be highly unstable and undergo some form of radioactive decay in a matter of nanoseconds. Marinov suggests that they could persist much longer without decaying if their nucleus was in a particular kind of excited state 鈥� highly deformed and spinning.
鈥淪uch an atom would be highly unstable, decaying in a matter of nanoseconds鈥�
Rolf-Dietmar Herzberg at the University of Liverpool in the UK is far from convinced. 鈥淭here are some gaping holes in the paper,鈥� he told New 杏吧原创. If there is a trace of this stuff in a purified solution of thorium, he says, there should be even more of it in natural minerals, in which case 鈥渋t鈥檚 ludicrous to assume no one would have spotted it before鈥�.
Kenneth Gregorich of Lawrence Berkeley National Laboratory in California, is also doubtful. 鈥淭o claim a new element, you need much better evidence. The general interpretation is going to be that there must be a problem with their technique.鈥�
