https://doi.org/10.1140/epjp/s13360-023-03787-8
Regular Article
Neutron elastic scattering kernel for Monte Carlo next-event estimators in Tripoli-4®
1
CEA, DES, IRESNE, DER, SPRC, Cadarache, 13108, Saint-Paul-lez-Durance, France
2
Service d’Etudes des Réacteurs et de Mathématiques Appliquées, Université Paris-Saclay, CEA, 91191, Gif-sur-Yvette, France
3
Centre Léon Bérard, CNRS, Inserm, CREATIS UMR 5220 U1294, Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon1, 69373, Lyon, France
4
CEA, DES, IRESNE, DER, SPESI, Cadarache, 13108, Saint-Paul-lez-Durance, France
Received:
28
October
2022
Accepted:
9
February
2023
Published online:
2
March
2023
This paper presents the implementation and the numerical validation of the exponential track length estimator (eTLE) for neutron transport in Tripoli-4®. The eTLE is a next-event estimator (NEE), which has the aim of doing variance reduction when paired with a forced-flight method. Like any other NEE, it hinges on deterministic transport through volumes with an attenuation factor applied to the particle’s weight. The application of NEEs to neutron-transport problems is impeded by the treatment of Doppler broadening. Indeed, the free-gas thermal treatment complicates the kinematic laws and changes the scattering probability, compared with an isotope at rest. Moreover, in crystalline materials, coherent elastic scattering is on the surface incompatible with NEEs due to its discrete angle scattering distribution. Because certain of the scattering angles are forbidden by the nature of the discrete distribution, and because NEEs are weighted by the differential scattering probability, the naive implementation of the NEE is biased. The paper surveys the evaluation of this quantity for the free-gas thermal treatment and for the coherent elastic scattering. Results to validate the implementations are benchmarked on a simple configuration against the classical unbiased track-length estimator (TLE) for several scattering nuclei and moderators.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
