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 ( σn,2n σn,M) (E) and ( σn,3n σn,M) (E). Aiming at the needs of the neutron data evaluator, σn,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 ( σn,M σne) (N, Z) and σne(N, Z), although the application of the formalism to heavy-mass elements presupposes a knowledge of σn,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