How orbiting electrons can lengthen nuclear half-life

Fission

Nuclear fission is the process in which a nucleus decays into two fragments. For large nucleii, this process is a complicated one in which the nucleus undergoes several stages of deformation before tearing itself apart.

In recent years, physicists have predicted that fission ought to be affected by the presence of electrons in orbit about the nucleus. That’s because any change in the shape of the nucleus naturally affects the electrons which tend to absorb energy making fission less likely. And the more electrons there are, the more energy they absorb. But the effect has never been observed because ordinary, naturally ocurring elements simply don’t have enough electrons to make this effect significant.

Today, Vlad Dzuba and Vic Flambuam at the University of New South Wales in Australia have calculated the strength of this effect for superheavy elements which would have more electrons. They say that although the effect is tiny for naturally ocurring nuclei with fewer than 100 or so protons, it would be hugely significant for these larger nuclei. In fact, they calculate that an atom with 160 protons would have double the expected half life because of this effect.

That could have significant implications for how much of this stuff we’re likely to find because elements that decay quickly tend to be rarer) . Last week, arxivblog reported on the potential discovery of element 122 (with 122 protons). Perhaps the groups looking for superheavies should be setting their sights much, much higher.

Ref: arxiv.org/abs/0805.1961: The Effect of Atomic Electrons on Nuclear Fission

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