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In a nuclear reactor gold can be manufactured by irradiation of platinum or mercury. Since platinum is more expensive than gold, platinum is economically unsuitable as a raw material. Only the mercury isotope Hg-196, which occurs with a frequency of 0.15% in natural mercury, can be converted to gold by neutron capture, and following K+- decay into Au-197 with slow neutrons. Other mercury isotopes are converted when irradiated with slow neutrons into one another or formed mercury isotopes, which beta decay into thallium. Using fast neutrons, the mercury isotope Hg-198, which is contained to 9.97% in natural mercury, can be converted by splitting off a neutron and becoming Hg-197, which then disintegrates to stable gold. This reaction, however, possesses a smaller activation cross-section and is feasible only with un-moderated reactors. It is also possible to eject several neutrons with very high energy into the other mercury isotopes in order to get the Hg-197. However such high-energy neutrons can be produced only by particle accelerators.
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