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Measurement of the α ratio and (n,γ) cross section of 235U from 0.2 to 200 eV at n_TOF

Balibrea-Correa, J.; Mendoza, E.; Cano-Ott, D.; González, E.; Capote, R.; Krtička, M.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Barbagallo, M.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Bosnar, D.; Brugger, M.; Calviani, M.; Calviño, F.; ... mehr

Abstract:
We measured the neutron capture-to-fission cross-section ratio (α ratio) and the capture cross section of $^{235}$U between 0.2 and 200 eV at the n_TOF facility at CERN. The simultaneous measurement of neutron-induced capture and fission rates was performed by means of the n_TOF BaF$_{2}$ Total Absorption Calorimeter (TAC), used for detection of γ rays, in combination with a set of micromegas detectors used as fission tagging detectors. The energy dependence of the capture cross section was obtained with help of the $^{6}$Li(n,t) standard reaction determining the n_TOF neutron fluence; the well-known integral of the $^{235}$U(n,f) cross section between 7.8 and 11 eV was then used for its absolute normalization. The α ratio, obtained with slightly higher statistical fluctuations, was determined directly, without need for any reference cross section. To perform the analysis of this measurement we developed a new methodology to correct the experimentally observed effect that the probabilities of detecting a fission reaction in the TAC and the micromegas detectors are not independent. The results of this work have been used in a new evaluation of $^{235}$U performed within the scope of the Collaborative International Evaluated Library Organisation (CIELO) Project, and are consistent with the ENDF/B-VIII.0 and JEFF-3.3 capture cross sections below 4 eV and above 100 eV. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000126505
Veröffentlicht am 20.11.2020
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Kernphysik (IKP)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 20.10.2020
Sprache Englisch
Identifikator ISSN: 0556-2813, 1089-490X, 1538-4497, 2469-9985, 2469-9993, 2470-0002
KITopen-ID: 1000126505
Erschienen in Physical review / C
Band 102
Heft 4
Seiten Art. Nr.: 044615
Nachgewiesen in Scopus
Web of Science
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