## Abstract

Simple analyses of (n, 2n) and (n, 3n) cross-sections are based on compound nucleus decay without branching. The result is an effective level-density parameter which is much smaller than the actual level-density parameter. Simple approximations of the energy distributions of the first and second neutrons in a multiple inelastic process (n, M) yield simple, closed-form formulae for the reduced (n, 2n) and (n, 3n) cross-sections, namely ( σ_{n,2n} σ_{n,M}) (E) and ( σ_{n,3n} σ_{n,M}) (E). Aiming at the needs of the neutron data evaluator, σ_{n,M}(E) is determined by normalization of the reduced (n, 2n) cross-section at a single experimental point. This is a more accurate alternative to using systemized ( σ_{n,M} σ_{ne}) (N, Z) and σ_{ne}(N, Z), although the application of the formalism to heavy-mass elements presupposes a knowledge of σ_{n,f}(E). The (n, 2n) and (n, 3n) cross-sections of nine nuclides with A > 150 are accurately reproduced by the formalism. This accuracy, in face of evidence of some non-compound processes, may be attributed to the ability of effective level-density parameters to account for the spectrum hardening effect of the non-compound processes.

Original language | English |
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Pages (from-to) | 239-252 |

Number of pages | 14 |

Journal | Annals of Nuclear Energy |

Volume | 5 |

Issue number | 6-7 |

DOIs | |

State | Published - 1 Jan 1978 |

Externally published | Yes |

## ASJC Scopus subject areas

- Nuclear Energy and Engineering