Angular momentum generation in nuclear fission

J N Wilson; D Thisse; M Lebois; N Jovančević; D Gjestvang; R Canavan; Matthias Rudigier; D Étasse; R-B Gerst; L Gaudefroy; E Adamska; P Adsley; A Algora; M Babo; K Belvedere; J Benito; G Benzoni; A Blazhev; M Bunce; R Chakma; A Boso; S Bottoni; N Cieplicka-Oryńczak; S Courtin; M L Cortés; P Davies; C Delafosse; M Fallot; B Fornal; L Fraile; A Gottardo; V Guadilla; G Häfner; K Hauschild; M Heine; C Henrich; I Homm; F Ibrahim; Ł W Iskra; P Ivanov; S Jazrawi; A Korgul; P Koseoglou; T Kröll; T Kurtukian-Nieto; L Le Meur; S Leoni; J Ljungvall; A Lopez-Martens; R Lozeva; I Matea; K Miernik; J Nemer; S Oberstedt; W Paulsen; M Piersa; Y Popovitch; C Porzio; L Qi; D Ralet; P H Regan; K Rezynkina; V Sánchez-Tembleque; S Siem; C Schmitt; P-A Söderström; C Sürder; G Tocabens; V Vedia; D Verney; N Warr; B Wasilewska; J Wiederhold; M Yavahchova; F Zeiser; S Ziliani

doi:10.1038/s41586-021-03304-w

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Angular momentum generation in nuclear fission

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Angular momentum generation in nuclear fission

J N Wilson, D Thisse, M Lebois, N Jovančević, D Gjestvang, R Canavan, Matthias Rudigier, D Étasse, R-B Gerst, L Gaudefroy, …

Nature (London), Vol.590(7847), pp.566-570

02/2021

DOI: https://doi.org/10.1038/s41586-021-03304-w

PMID: 33627809

Abstract

When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning; this phenomenon has been a mystery in nuclear physics for over 40 years. The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum. Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the γ-ray heating problem in nuclear reactors, for the study of the structure of neutron-rich isotopes, and for the synthesis and stability of super-heavy elements.

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Title: Angular momentum generation in nuclear fission
Creators: J N Wilson
D Thisse - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
M Lebois - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
N Jovančević - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
D Gjestvang - Department of Physics, University of Oslo, Blindern, Oslo, Norway
R Canavan - University of Surrey, School of Maths and Physics
Matthias Rudigier - University of Surrey
D Étasse - LPC Caen, Caen, France
R-B Gerst - Institut für Kernphysik, Universität zu Köln, Cologne, Germany
L Gaudefroy - CEA/DAM Bruyères-le-Châtel, Arpajon, France
E Adamska - Faculty of Physics, University of Warsaw, Warsaw, Poland
P Adsley - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
A Algora - Institute for Nuclear Research (Atomki), Debrecen, Hungary
M Babo - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
K Belvedere
J Benito - Grupo de Fisica Nuclear & IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain
G Benzoni - INFN, Milan, Italy
A Blazhev - Institut für Kernphysik, Universität zu Köln, Cologne, Germany
M Bunce - National Physical Laboratory, Teddington, UK
R Chakma - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
A Boso - National Physical Laboratory, Teddington, UK
S Bottoni - Dipartimento di Fisica, Universitá degli Studi di Milano, Milan, Italy
N Cieplicka-Oryńczak - Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
S Courtin - Université de Strasbourg, CNRS, IPHC UMR 7178, Strasbourg, France
M L Cortés - RIKEN Nishina Center, Hirosawa, Japan
P Davies - School of Physics and Astronomy, University of Manchester, Manchester, UK
C Delafosse - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
M Fallot - Subatech, IMT-Atlantique, Université de Nantes, Nantes, France
B Fornal - Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
L Fraile - Grupo de Fisica Nuclear & IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain
A Gottardo - INFN Laboratori Nazionali di Legnaro, Legnaro, Italy
V Guadilla - Subatech, IMT-Atlantique, Université de Nantes, Nantes, France
G Häfner - Institut für Kernphysik, Universität zu Köln, Cologne, Germany
K Hauschild - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
M Heine - Université de Strasbourg, CNRS, IPHC UMR 7178, Strasbourg, France
C Henrich - Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Darmstadt, Germany
I Homm - Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Darmstadt, Germany
F Ibrahim - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
Ł W Iskra - Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
P Ivanov - National Physical Laboratory, Teddington, UK
S Jazrawi - University of Surrey, School of Maths and Physics
A Korgul - Faculty of Physics, University of Warsaw, Warsaw, Poland
P Koseoglou - GSI Helmoltzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
T Kröll - Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Darmstadt, Germany
T Kurtukian-Nieto - Université de Bordeaux, CNRS, CENBG UMR 5797, Gradignan, France
L Le Meur - Subatech, IMT-Atlantique, Université de Nantes, Nantes, France
S Leoni - Dipartimento di Fisica, Universitá degli Studi di Milano, Milan, Italy
J Ljungvall - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
A Lopez-Martens - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
R Lozeva - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
I Matea - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
K Miernik - Faculty of Physics, University of Warsaw, Warsaw, Poland
J Nemer - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
S Oberstedt - European Commission, Joint Research Centre, Geel, Belgium
W Paulsen - Department of Physics, University of Oslo, Blindern, Oslo, Norway
M Piersa - Faculty of Physics, University of Warsaw, Warsaw, Poland
Y Popovitch - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
C Porzio - TRIUMF, Vancouver, British Columbia, Canada
L Qi - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
D Ralet - Grand Accélérateur National d'Ions Lourds, Caen, France
P H Regan - University of Surrey, School of Maths and Physics
K Rezynkina - Institute for Nuclear and Radiation Physics, Katholieke Universiteit Leuven, Leuven, Belgium
V Sánchez-Tembleque - Grupo de Fisica Nuclear & IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain
S Siem - Department of Physics, University of Oslo, Blindern, Oslo, Norway
C Schmitt - Université de Strasbourg, CNRS, IPHC UMR 7178, Strasbourg, France
P-A Söderström - Extreme Light Infrastructure-Nuclear Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, Bucharest-Măgurele, Romania
C Sürder - Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Darmstadt, Germany
G Tocabens - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
V Vedia - Grupo de Fisica Nuclear & IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain
D Verney - Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
N Warr - Institut für Kernphysik, Universität zu Köln, Cologne, Germany
B Wasilewska - Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
J Wiederhold - Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Darmstadt, Germany
M Yavahchova - Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia, Bulgaria
F Zeiser - Department of Physics, University of Oslo, Blindern, Oslo, Norway
S Ziliani - Dipartimento di Fisica, Universitá degli Studi di Milano, Milan, Italy
Publication Details: Nature (London), Vol.590(7847), pp.566-570
Publisher: Nature Research ; England
Date published: 02/2021
Date accepted: 09/12/2020
Identifiers: 99548621802346
Academic Unit: School of Maths and Physics
Language: English
Resource Type: Journal article

Angular momentum generation in nuclear fission

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