Published June 1986 | Version v1
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Probability tables. Application to cross section processing for neutronic. First part: With the statistical hypothesis

Creators

Description

The idea of describing neutron cross-section fluctuations by sets of discrete values, called 'probability tables', was formulated some 15 years ago. We propose to define the probability tables from moments by equating the moments of the actual cross-section distribution in a given energy range to the moments of the table. This definition introduces PADE approximants, orthogonal polynomials and Gauss quadrature. This mathematical basis applies very well to the total cross-section. Some difficulties appear when partial cross-sections are taken into account, linked to the ambiguity of the definition of multivariate PADE approximants. Nevertheless, we propose solutions and choices which appear to be satisfactory. Comparisons are made with other definitions of probability tables and the calculation of mixtures of nuclei is considered. (author)

Abstract (French)

L'idee de decrire les fluctuations des sections efficaces par des jeux de valeurs discretes, appeles 'tables de probabilite', a ete proposee vers 1970. Nous proposons de decrire les tables de probabilites en egalant les moments de la distribution des sections efficaces a ceux de la table de probabilite. Cette definition introduit les polynomes orthogonaux et la quadrature de Gauss par l'intermediaire des approximants de PADE. Cette base mathematique s'applique tres bien a la section efficace totale. Des difficultes apparaissent quand les sections partielles sont prises en compte, difficultes liees a l'ambiguite de la definition d'approximants de PADE a plusieurs variables. Neanmoins, nous proposons des solutions et des choix qui semblent satisfaisants. Des comparaisons sont faites avec d'autres definitions des tables probabilite, et le calcul de melanges de noyaux est examine. (auteurs)

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Additional details

Additional titles

Original title (French)
Les tables de probabilite. Application au traitement des sections efficaces pour la neutronique. Premiere partie: dans l'hypothese statistique

Identifiers

URL
http://www.iaea.org/inis/Contacts/;

Publishing Information

Imprint Pagination
86 p.
Report number
CEA-N--2485

INIS

Country of Publication
France
Country of Input or Organization
France
INIS RN
45061280
Subject category
S73: NUCLEAR PHYSICS AND RADIATION PHYSICS;
Descriptors DEI
ACCURACY; CROSS SECTIONS; FLUCTUATIONS; NEUTRON TRANSPORT THEORY; NUCLEAR PROPERTIES; NUCLEAR REACTIONS; ORTHOGONAL TRANSFORMATIONS; PADE APPROXIMATION; PROBABILITY; QUADRATURES; STATISTICAL MODELS
Descriptors DEC
APPROXIMATIONS; CALCULATION METHODS; MATHEMATICAL MODELS; TRANSFORMATIONS; TRANSPORT THEORY; VARIATIONS

Optional Information

Notes
32 refs.; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS website for current contact and E-mail addresses: http://www.iaea.org/inis/Contacts/