Inelastic neutron scattering on <math xmlns="http://www.w3.org/1998/Math/MathML"><mmultiscripts><mi mathvariant="normal">U</mi><mprescripts></mprescripts><none></none><mn>238</mn></mmultiscripts></math> with <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>γ</mi></math>-ray coincidence spectroscopy

Nu-Ball Collaboration; Carole Chatel; Jonathan Wilson; Philippe Dessagne; Greg Henning; Maëlle Kerveno; P. Aguilera; A. Algora; G. de Angelis; J. Benito; D. Bittner; A. Blazhev; S. Bottoni; J. A. Briz; R. Canavan; F. Didierjean; G. Duchêne; A. Esmaylzadeh; J. Fischer; B. Fornal; L. M. Fraile; E. R. Gamba; R. B. Gerst; K. A. Gladnishki; G. Häfner; K. Hauschild; J. Heery; C. Henrich; C. Hiver; I. Homm; Ł. W. Iskra; N. Jovancevic; D. Kalaydjieva; L. Knafla; D. Knezevic; D. Kocheva; A. Korgul; G. Kosir; T. Kröll; M. Lebois; S. Leoni; J. Ljungvall; M. Llanos-Expósito; A. Lopez-Martens; E. Lovšin; R. Lozeva; M. Markova; A. Messingschlager; K. Miernik; T. Milanovic; M. Moukaddam; J. R. Murias; A. Oberstedt; S. Oberstedt; S. Pascu; G. Pasqualato; W. Paulsen; Zs. Podolyák; W. Poklepa; P. H. Regan; K. Rezynkina; M. Rudigier; V. Sánchez-Tembleque; K. Solak; K. Stoychev; M. Stryjczyk; C. Sürder; D. Thisse; Ma. von Tresckow; V. Vedia; J. Vesic; N. Warr

doi:10.1103/jrh6-rh6h

Inelastic neutron scattering on ${}^{238}U$ with $γ$ -ray coincidence spectroscopy

Carole Chatel ^{1,2,3,4,*,†}, Jonathan Wilson ⁵, Philippe Dessagne¹, Greg Henning ¹, Maëlle Kerveno ¹, P. Aguilera ^6,7,8, A. Algora ^9,10, G. de Angelis ¹¹, J. Benito^6,7,12 et al. (Nu-Ball Collaboration)

J. Benito^6,7,12, D. Bittner ¹³, A. Blazhev ¹³, S. Bottoni ^14,15, J. A. Briz ¹⁶, R. Canavan ^17,18, F. Didierjean ¹, G. Duchêne ¹, A. Esmaylzadeh ¹³, J. Fischer ¹³, B. Fornal ¹⁹, L. M. Fraile ¹⁶, E. R. Gamba ^14,15, R. B. Gerst ¹³, K. A. Gladnishki ²⁰, G. Häfner ^5,13, K. Hauschild ⁵, J. Heery ¹⁷, C. Henrich², C. Hiver ⁵, I. Homm ², Ł. W. Iskra ¹⁹, N. Jovancevic ²¹, D. Kalaydjieva ²², L. Knafla ¹³, D. Knezevic ²³, D. Kocheva ²⁰, A. Korgul ²⁴, G. Kosir ^25,26, T. Kröll ^2,4, M. Lebois ⁵, S. Leoni ^14,15, J. Ljungvall ^1,5, M. Llanos-Expósito ¹⁶, A. Lopez-Martens⁵, E. Lovšin^25,26, R. Lozeva ⁵, M. Markova ²⁷, A. Messingschlager², K. Miernik ²⁴, T. Milanovic ²⁸, M. Moukaddam ¹, J. R. Murias ^16,29, A. Oberstedt ³⁰, S. Oberstedt ³¹, S. Pascu ^17,32, G. Pasqualato ⁵, W. Paulsen ²⁷, Zs. Podolyák ¹⁷, W. Poklepa^7,24, P. H. Regan ^17,18, K. Rezynkina ⁶, M. Rudigier^2,4, V. Sánchez-Tembleque ¹⁶, K. Solak ²⁴, K. Stoychev ³³, M. Stryjczyk ^34,35, C. Sürder^2,4, D. Thisse ²², Ma. von Tresckow ^2,4, V. Vedia^16,36, J. Vesic ²⁵, and N. Warr ¹³ (Nu-Ball Collaboration)

¹Université de Strasbourg, CNRS, IPHC/DRS UMR 7178, 23 Rue du Loess, F-67037 Strasbourg, France
²Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Schlossgartenstrasse, 9, 64289 Darmstadt, Germany
³GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
⁴Helmholtz Research Academy Hesse for FAIR (HFHF), GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany
⁵CNRS, IJClab Orsay, bât 100, 15 rue G. Clemenceau, 91406 Orsay Cedex, France
⁶Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Padova, Italy
⁷Università degli Studi di Padova, Padova, Italy
⁸Centro de Investigación en Física Nuclear y Espectroscopia de Neutrones CEFNEN, Comisión Chilena de Energía Nuclear, Santiago, Chile
⁹IFIC, CSIC-University of Valencia, Valencia, Spain
¹⁰HUN-REN Institute of Nuclear Research, Debrecen, Hungary
¹¹INFN Laboratori Nazionali di Legnaro, Legnaro, Italy
¹²Grupo de Fisica Nuclear, Universidad Complutense de Madrid, Madrid, Spain
¹³Institut für Kernphysik, Universität zu Köln, Cologne, Germany
¹⁴Dipartimento di Fisica, Universitá degli Studi di Milano, Milan, Italy
¹⁵Istituto Nazionale di Fisica Nucleare sez. Milano, Milan, Italy
¹⁶Grupo de Física Nuclear, EMFTEL & IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, E-28040 Madrid, Spain
¹⁷School of Mathematics. Physics and Space, University of Surrey, Guildford GU2 7XH, United Kingdom
¹⁸Medical Marine and Nuclear Department, National Physical Laboratory, Teddington TW11 0LW, United Kingdom
¹⁹Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
²⁰Faculty of Physics, St. Kliment Ohridski University of Sofia, 1164 Sofia, Bulgaria
²¹University of Novi Sad, Novi Sad, Serbia
²²IRFU/DPhN, CEA Saclay, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
²³Institute of Physics Belgrade, Belgrade, Serbia
²⁴Faculty of Physics, University of Warsaw, PL 02-093 Warsaw, Poland
²⁵Jožef Stefan Institute, Ljubljana, Slovenia
²⁶University of Ljubljana, Ljubljana, Slovenia
²⁷Department of Physics, University of Oslo, Oslo, Norway
²⁸Vinča Institute of Nuclear Sciences, Belgrade, Serbia
²⁹Rutherford Appleton Laboratory - UKRI, Didcot OX11 0QX, United Kingdom
³⁰Extreme Light Infrastructure - Nuclear Physics, “Horia Hulubei” National Institute for R&D in Physics and Nuclear Engineering, 30 Reactorului Street, 077125 Magurele, Romania
³¹European Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, 2440 Geel, Belgium
³²“Horia Hulubei” National Institute for R&D in Physics and Nuclear Engineering, R-77125 Bucharest-Magurele, Romania
³³Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France
³⁴University of Jyvaskyla, Department of Physics, Accelerator Laboratory, P.O. Box 35(YFL) FI-40014 University of Jyvaskyla, Finland
³⁵Institut Laue-Langevin, 71 Avenue des Martyrs, F-38042 Grenoble, France
³⁶ISOLDE, CERN, 1211 Geneva 23, Switzerland

^*Contact author: carole.chatel@eli-np.ro
^†Present address: Extreme Light Infrastructure - Nuclear Physics, IFIN-HH, 30 Reactorului Street, 077125 Magurele, Romania.

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Phys. Rev. C 113, 064320 – Published 30 June, 2026

DOI: https://doi.org/10.1103/jrh6-rh6h

Abstract

Improvement of the accuracy of neutronics simulation of actual or future reactor designs is essential and requires a better knowledge of the core neutron population. The reactor neutron population is partially driven by $(n, x n)$ reactions that change the number and decrease the energy of the neutrons. However, the cross sections of these reactions are currently not measured with sufficient precision. This is particularly the case for the neutron inelastic-scattering cross section of ${}^{238}U$ , which represents around 90%–95% of the mass of fuel in present and many future reactor core designs. It therefore features on the High Priority Request List for measurement improvement. This cross section can be measured using prompt $γ$ -ray spectroscopy coupled to neutron time-of-flight measurements, where the total $(n, n^{'})$ cross section can be deduced from a combination of the measured $(n, n^{'} γ)$ partial cross sections and the level scheme information. The knowledge of the ${}^{238}U$ level scheme is still very incomplete, inducing significant uncertainties on the resulting inelastic-scattering cross section. Therefore, an effort has recently been carried out to experimentally revisit the ${}^{238}U$ decay scheme by performing high-resolution coincidence spectroscopy of the ${}^{238}U (n, n^{'})$ reaction. To obtain detailed level scheme information, the $ν$ -Ball $γ$ spectrometer was coupled to the LICORNE directional neutron source of the ALTO facility, allowing the study of inelastic scattering of fast neutrons (0.5–3 MeV) on ${}^{238}U$ via $γ − γ$ coincidence spectroscopy. Coincidence matrices obtained during the first and the second $ν$ -Ball campaigns were analyzed using the RadWare ESCL8R software. 110 $γ$ transitions and 60 levels registered in the Evaluated Nuclear Structure Data File database have been confirmed, and 158 new $γ$ transitions and 58 new levels have been found. Although not exhaustive, the ${}^{238}U$ level scheme information has been significantly improved, and its completeness has been estimated to be up to 1.7214 MeV compared with 1.27854 MeV at present. It is hence expected to decrease the uncertainties of ${}^{238}U (n, n^{'})$ cross sections, which is needed for accurate reactor core modeling.

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22 July, 2026

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Inelastic neutron scattering on ${}^{238}U$ with $γ$ -ray coincidence spectroscopy

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Inelastic neutron scattering on U238 with γ-ray coincidence spectroscopy

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Inelastic neutron scattering on ${}^{238}U$ with $γ$ -ray coincidence spectroscopy