type of nuclear reaction in which a target nucleus absorbs a neutron (uncharged particle), then emits a discrete quantity of electromagnetic energy (gamma-ray photon). The target nucleus and the product nucleus are isotopes, or forms of the same element. Thus phosphorus-31, on undergoing neutron capture, becomes phosphorus-32. The heavier isotope that results may be radioactive, so that neutron capture, which occurs with almost any nucleus, is a common way of producing radioactive isotopes.
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