Author: G. Rudstam 1
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  • 1 The Swedish Research Councils' Laboratory Studsvik, Fack S-611 01 Nyköping Sweden
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The experimental delayed-neutron spectra of 25 precursors in fission have been described in terms of a series of fine structure peaks superimposed on a gross structure consisting of 1–3 components corresponding to different wave-numbers. These precursors are responsible for 85–87% of the delayed-neutron effect in nuclear fuel. By including also some precursors whose spectra have been deduced by an extrapolation procedure the effective delayed-neutron energy distribution in nuclear fuel can be accurately calculated. As a byproduct the applicability of some recent mass formulas in the region of very neutron-rich nuclei has been tested. Systematic deviations have been found, which indicate the need of further investigations.