TY - JOUR
T1 - Measurement of the α ratio and (n,γ) cross section of U 235 from 0.2 to 200 eV at n_TOF MEASUREMENT of the α RATIO and ... J. BALIBREA-CORREA et al.
AU - n TOF Collaboration
AU - Balibrea-Correa, J.
AU - Mendoza, E.
AU - Cano-Ott, D.
AU - González, E.
AU - Capote, R.
AU - Krtička, M.
AU - Altstadt, S.
AU - Andrzejewski, J.
AU - Audouin, L.
AU - Bécares, V.
AU - Barbagallo, M.
AU - Bečvář, F.
AU - Belloni, F.
AU - Berthoumieux, E.
AU - Billowes, J.
AU - Boccone, V.
AU - Bosnar, D.
AU - Brugger, M.
AU - Calviani, M.
AU - Calviño, F.
AU - Carrapiço, C.
AU - Cerutti, F.
AU - Chiaveri, E.
AU - Chin, M.
AU - Colonna, N.
AU - Cortés, G.
AU - Cortés-Giraldo, M. A.
AU - Diakaki, M.
AU - Domingo-Pardo, C.
AU - Dressler, R.
AU - Durán, I.
AU - Eleftheriadis, C.
AU - Ferrari, A.
AU - Fraval, K.
AU - Furman, V.
AU - Göbel, K.
AU - Gómez-Hornillos, M. B.
AU - Ganesan, S.
AU - García, A. R.
AU - Giubrone, G.
AU - Gonçalves, I. F.
AU - Goverdovski, A.
AU - Griesmayer, E.
AU - Guerrero, C.
AU - Gunsing, F.
AU - Heftrich, T.
AU - Hernández-Prieto, A.
AU - Heyse, J.
AU - Jenkins, D. G.
AU - Rauscher, T.
N1 - © 2020 the Author(s). Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/). Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
PY - 2020/10/20
Y1 - 2020/10/20
N2 - We measured the neutron capture-to-fission cross-section ratio (α ratio) and the capture cross section of U235 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 BaF2 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 Li6(n,t) standard reaction determining the n_TOF neutron fluence; the well-known integral of the U235(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 U235 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. However, the measured capture cross section is on average 10% larger between 4 and 100 eV.
AB - We measured the neutron capture-to-fission cross-section ratio (α ratio) and the capture cross section of U235 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 BaF2 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 Li6(n,t) standard reaction determining the n_TOF neutron fluence; the well-known integral of the U235(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 U235 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. However, the measured capture cross section is on average 10% larger between 4 and 100 eV.
UR - http://www.scopus.com/inward/record.url?scp=85095131388&partnerID=8YFLogxK
U2 - 10.1103/PhysRevC.102.044615
DO - 10.1103/PhysRevC.102.044615
M3 - Article
AN - SCOPUS:85095131388
SN - 2469-9985
VL - 102
JO - Physical Review C (nuclear physics)
JF - Physical Review C (nuclear physics)
IS - 4
M1 - 044615
ER -