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Wilson JN, Thisse D, Lebois M, Jovančević N, Gjestvang D, Canavan R, Rudigier M, Étasse D, Gerst RB, Gaudefroy L, Adamska E, Adsley P, Algora A, Babo M, Belvedere K, Benito J, Benzoni G, Blazhev A, Boso A, Bottoni S, Bunce M, Chakma R, Cieplicka-Oryńczak N, Courtin S, Cortés ML, Davies P, Delafosse C, Fallot M, Fornal B, Fraile L, Gottardo A, Guadilla V, Häfner G, Hauschild K, Heine M, Henrich C, Homm I, Ibrahim F, Iskra ŁW, Ivanov P, Jazrawi S, Korgul A, Koseoglou P, Kröll T, Kurtukian-Nieto T, Le Meur L, Leoni S, Ljungvall J, Lopez-Martens A, Lozeva R, Matea I, Miernik K, Nemer J, Oberstedt S, Paulsen W, Piersa M, Popovitch Y, Porzio C, Qi L, Ralet D, Regan PH, Rezynkina K, Sánchez-Tembleque V, Siem S, Schmitt C, Söderström PA, Sürder C, Tocabens G, Vedia V, Verney D, Warr N, Wasilewska B, Wiederhold J, Yavahchova M, Zeiser F, Ziliani S. Angular momentum generation in nuclear fission. Nature 2021; 590:566-570. [PMID: 33627809 DOI: 10.1038/s41586-021-03304-w] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 12/09/2020] [Indexed: 01/31/2023]
Abstract
When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning1; this phenomenon has been a mystery in nuclear physics for over 40 years2,3. 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 momentum4-12. 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 reactors13,14, for the study of the structure of neutron-rich isotopes15,16, and for the synthesis and stability of super-heavy elements17,18.
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Affiliation(s)
- J N Wilson
- Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France.
| | - 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
- Department of Physics, University of Surrey, Guildford, UK.,National Physical Laboratory, Teddington, UK
| | - M Rudigier
- Department of Physics, University of Surrey, Guildford, UK.,Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Darmstadt, Germany
| | | | - R-B Gerst
- Institut für Kernphysik, Universität zu Köln, Cologne, Germany
| | | | - E Adamska
- Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - P Adsley
- Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
| | - A Algora
- IFIC, CSIC-University of Valencia, Valencia, Spain.,Institute for Nuclear Research (Atomki), Debrecen, Hungary
| | - M Babo
- Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
| | - K Belvedere
- Department of Physics, University of Surrey, Guildford, UK
| | - J Benito
- Grupo de Fisica Nuclear & IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain
| | | | - A Blazhev
- Institut für Kernphysik, Universität zu Köln, Cologne, Germany
| | - A Boso
- National Physical Laboratory, Teddington, UK
| | - S Bottoni
- INFN, Milan, Italy.,Dipartimento di Fisica, Universitá degli Studi di Milano, Milan, Italy
| | - M Bunce
- National Physical Laboratory, Teddington, UK
| | - R Chakma
- Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France
| | | | - S Courtin
- Université de Strasbourg, CNRS, IPHC UMR 7178, Strasbourg, France
| | | | - 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
- Université Paris-Saclay, CNRS/IN2P3, IJC Laboratory, Orsay, France.,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
- INFN, Milan, Italy.,Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
| | - P Ivanov
- National Physical Laboratory, Teddington, UK
| | - S Jazrawi
- Department of Physics, University of Surrey, Guildford, UK.,National Physical Laboratory, Teddington, UK
| | - A Korgul
- Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - P Koseoglou
- Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Darmstadt, Germany.,GSI Helmoltzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
| | - T Kröll
- Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Darmstadt, Germany
| | | | - L Le Meur
- Subatech, IMT-Atlantique, Université de Nantes, Nantes, France
| | - S Leoni
- INFN, Milan, Italy.,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
- INFN, Milan, Italy.,Dipartimento di Fisica, Universitá degli Studi di Milano, Milan, Italy.,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
- Department of Physics, University of Surrey, Guildford, UK.,National Physical Laboratory, Teddington, UK
| | - 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
- Technische Universität Darmstadt, Fachbereich Physik, Institut für Kernphysik, Darmstadt, Germany.,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
- INFN, Milan, Italy.,Dipartimento di Fisica, Universitá degli Studi di Milano, Milan, Italy
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Carroll RJ, Podolyák Z, Berry T, Grawe H, Alexander T, Andreyev AN, Ansari S, Borge MJG, Brunet M, Creswell JR, Fraile LM, Fahlander C, Fynbo HOU, Gamba ER, Gelletly W, Gerst RB, Górska M, Gredley A, Greenlees PT, Harkness-Brennan LJ, Huyse M, Judge SM, Judson DS, Konki J, Kurcewicz J, Kuti I, Lalkovski S, Lazarus IH, Lică R, Lund M, Madurga M, Marginean N, Marginean R, Marroquin I, Mihai C, Mihai RE, Nácher E, Negret A, Nita C, Pascu S, Page RD, Patel Z, Perea A, Phrompao J, Piersa M, Pucknell V, Rahkila P, Rapisarda E, Regan PH, Rotaru F, Rudigier M, Shand CM, Shearman R, Stegemann S, Stora T, Sotty C, Tengblad O, Van Duppen P, Vedia V, Wadsworth R, Walker PM, Warr N, Wearing F, De Witte H. Competition between Allowed and First-Forbidden β Decay: The Case of ^{208}Hg→^{208}Tl. Phys Rev Lett 2020; 125:192501. [PMID: 33216605 DOI: 10.1103/physrevlett.125.192501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/21/2020] [Accepted: 10/07/2020] [Indexed: 06/11/2023]
Abstract
The β decay of ^{208}Hg into the one-proton hole, one neutron-particle _{81}^{208}Tl_{127} nucleus was investigated at CERN-ISOLDE. Shell-model calculations describe well the level scheme deduced, validating the proton-neutron interactions used, with implications for the whole of the N>126, Z<82 quadrant of neutron-rich nuclei. While both negative and positive parity states with spin 0 and 1 are expected within the Q_{β} window, only three negative parity states are populated directly in the β decay. The data provide a unique test of the competition between allowed Gamow-Teller and Fermi, and first-forbidden β decays, essential for the understanding of the nucleosynthesis of heavy nuclei in the rapid neutron capture process. Furthermore, the observation of the parity changing 0^{+}→0^{-}β decay where the daughter state is core excited is unique, and can provide information on mesonic corrections of effective operators.
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Affiliation(s)
- R J Carroll
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - Zs Podolyák
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
- ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt, Germany
| | - T Berry
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - H Grawe
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt, Germany
| | - T Alexander
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - A N Andreyev
- University of York, Dept Phys, North Yorkshire YO10 5DD, United Kingdom
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195, Japan
| | - S Ansari
- Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - M J G Borge
- CERN, Physics Department, 1211 Geneva 23, Switzerland
| | - M Brunet
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - J R Creswell
- Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - L M Fraile
- Grupo de Física Nuclear & IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, E-28040 Madrid, Spain
| | - C Fahlander
- Department of Physics, Lund University, S-22100 Lund, Sweden
| | - H O U Fynbo
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus, Denmark
| | - E R Gamba
- University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - W Gelletly
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - R-B Gerst
- Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - M Górska
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt, Germany
| | - A Gredley
- Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - P T Greenlees
- University of Jyvaskyla, Department of Physics, University of Jyvaskyla, P.O. Box 35, FI-40014 Jyvaskyla, Finland
- Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - L J Harkness-Brennan
- Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - M Huyse
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, 3001 Leuven, Belgium
| | - S M Judge
- National Physical Laboratory, Teddington, Middlesex TW11 0LW, United Kingdom
| | - D S Judson
- Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - J Konki
- University of Jyvaskyla, Department of Physics, University of Jyvaskyla, P.O. Box 35, FI-40014 Jyvaskyla, Finland
- Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - J Kurcewicz
- CERN, Physics Department, 1211 Geneva 23, Switzerland
| | - I Kuti
- Institute of Nuclear Research of the Hungarian Academy of Sciences, 4026 Debrecen, Hungary
| | - S Lalkovski
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - I H Lazarus
- STFC, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
| | - R Lică
- CERN, Physics Department, 1211 Geneva 23, Switzerland
- Horea Hulubei National Institute for Physics and Nuclear Engineering, RO-077125 Bucharest, Romania
| | - M Lund
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus, Denmark
| | - M Madurga
- CERN, Physics Department, 1211 Geneva 23, Switzerland
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - N Marginean
- Horea Hulubei National Institute for Physics and Nuclear Engineering, RO-077125 Bucharest, Romania
| | - R Marginean
- Horea Hulubei National Institute for Physics and Nuclear Engineering, RO-077125 Bucharest, Romania
| | - I Marroquin
- Instituto de Estructura de la Materia, CSIC, Serrano 113 bis, E-28006 Madrid, Spain
| | - C Mihai
- Horea Hulubei National Institute for Physics and Nuclear Engineering, RO-077125 Bucharest, Romania
| | - R E Mihai
- Horea Hulubei National Institute for Physics and Nuclear Engineering, RO-077125 Bucharest, Romania
| | - E Nácher
- Instituto de Estructura de la Materia, CSIC, Serrano 113 bis, E-28006 Madrid, Spain
| | - A Negret
- Horea Hulubei National Institute for Physics and Nuclear Engineering, RO-077125 Bucharest, Romania
| | - C Nita
- University of Brighton, Brighton BN2 4GJ, United Kingdom
- Horea Hulubei National Institute for Physics and Nuclear Engineering, RO-077125 Bucharest, Romania
| | - S Pascu
- Horea Hulubei National Institute for Physics and Nuclear Engineering, RO-077125 Bucharest, Romania
| | - R D Page
- Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - Z Patel
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - A Perea
- Instituto de Estructura de la Materia, CSIC, Serrano 113 bis, E-28006 Madrid, Spain
| | - J Phrompao
- Department of Physics and Materials Science, Chiang Mai University, 50200 Chiang Mai, Thailand
| | - M Piersa
- Faculty of Physics, University of Warsaw, PL 02-093 Warsaw, Poland
| | - V Pucknell
- STFC, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
| | - P Rahkila
- University of Jyvaskyla, Department of Physics, University of Jyvaskyla, P.O. Box 35, FI-40014 Jyvaskyla, Finland
- Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - E Rapisarda
- CERN, Physics Department, 1211 Geneva 23, Switzerland
| | - P H Regan
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
- National Physical Laboratory, Teddington, Middlesex TW11 0LW, United Kingdom
| | - F Rotaru
- Horea Hulubei National Institute for Physics and Nuclear Engineering, RO-077125 Bucharest, Romania
| | - M Rudigier
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - C M Shand
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - R Shearman
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
- National Physical Laboratory, Teddington, Middlesex TW11 0LW, United Kingdom
| | - S Stegemann
- Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - T Stora
- CERN, Physics Department, 1211 Geneva 23, Switzerland
| | - Ch Sotty
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, 3001 Leuven, Belgium
- Horea Hulubei National Institute for Physics and Nuclear Engineering, RO-077125 Bucharest, Romania
| | - O Tengblad
- Instituto de Estructura de la Materia, CSIC, Serrano 113 bis, E-28006 Madrid, Spain
| | - P Van Duppen
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, 3001 Leuven, Belgium
| | - V Vedia
- Grupo de Física Nuclear & IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, E-28040 Madrid, Spain
| | - R Wadsworth
- University of York, Dept Phys, North Yorkshire YO10 5DD, United Kingdom
| | - P M Walker
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - N Warr
- Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - F Wearing
- Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - H De Witte
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, 3001 Leuven, Belgium
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