Fission fragment angular distribution and fission cross section validation
type: Dataset
description: The present knowledge of angular distributions of neutron-induced fission is limited to a maximal energy of 15 MeV, with large discrepancies around 14 MeV. Only 238U and 232Th have been investigated up to 100 MeV in a single experiment. The n_TOF Collaboration performed the fission cross section measurement of several actinides (232Th, 235U, 238U, 234U, 237Np) at the n_TOF facility using an experimental set-up made of Parallel Plate Avalanche Counters (PPAC), extending the energy domain of the incident neutron above hundreds of MeV. The method based on the detection of the 2 fragments in coincidence allowed to clearly disentangle the fission reactions among other types of reactions occurring in the spallation domain. I will show the methods we used to reconstruct the full angular resolution by the tracking of fission fragments. Below 10 MeV our results are consistent with existing data. For example in the case of 232Th, below 10 MeV the results show clearly the variation occurring at the first (1 MeV) and second (7 MeV) chance fission, corresponding to transition states of given J and K (total spin and its projection on the fission axis), and a much more accurate energy dependence at the 3rd chance threshold (14 MeV) has been obtained. In the spallation domain, above 30 MeV we confirm the high anisotropy revealed in 232Th by the single existing data set. I'll discuss the implications of this finding, related to the low anisotropy exhibited in proton-induced fission. I also explore the critical experiments which is valuable checks of nuclear data. The 237Np neutron-induced fission cross section has recently been measured in a large energy range (from eV to GeV) at the n TOF facility at CERN. When compared to previous measurements, the n TOF fission cross section appears to be higher by 5-7 % beyond the fission threshold. To check the relevance of n TOF data, we simulate a criticality experiment performed at Los Alamos with a 6 kg sphere of 237Np. This sphere was surr…
landing page: https://theses.hal.science/tel-00924483
identifier: NNT: 2013PA112186
keyword: criticality
keyword: criticite
keyword: cross-section
keyword: distribution-angulaire
keyword: donnees-nucleaires
keyword: endfb
keyword: fission
keyword: fission-fragment-angular-distribution-ffad
keyword: infoeu-reposemanticsdoctoralthesis
keyword: neptunium
keyword: nuclear-data
keyword: physcondcm-genphysics-physicscondensed-matter-cond-matother-cond-matother
keyword: section-efficace
keyword: theses
keyword: thorium
issued: 2026-05-07T15:22:32.722764
modified: 2026-05-07T15:22:32.722768
language: en
contact point: Organization
  fn: CCSD

test_moissonnage_selune
type: Agent

Fission fragment angular distribution and fission cross section validation
type: Distribution
format: HTML
access URL: https://theses.hal.science/tel-00924483
issued: 2026-05-07T15:22:32.732152
modified: 2026-05-07T15:22:32.709649