1
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Bennett SA, Garrett K, Sharp DK, Freeman SJ, Smith AG, Wright TJ, Kay BP, Tang TL, Tolstukhin IA, Ayyad Y, Chen J, Davies PJ, Dolan A, Gaffney LP, Heinz A, Hoffman CR, Müller-Gatermann C, Page RD, Wilson GL. Direct Determination of Fission-Barrier Heights Using Light-Ion Transfer in Inverse Kinematics. PHYSICAL REVIEW LETTERS 2023; 130:202501. [PMID: 37267578 DOI: 10.1103/physrevlett.130.202501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/28/2023] [Accepted: 03/27/2023] [Indexed: 06/04/2023]
Abstract
We demonstrate a new technique for obtaining fission data for nuclei away from β stability. These types of data are pertinent to the astrophysical r process, crucial to a complete understanding of the origin of the heavy elements, and for developing a predictive model of fission. These data are also important considerations for terrestrial applications related to power generation and safeguarding. Experimentally, such data are scarce due to the difficulties in producing the actinide targets of interest. The solenoidal-spectrometer technique, commonly used to study nucleon-transfer reactions in inverse kinematics, has been applied to the case of transfer-induced fission as a means to deduce the fission-barrier height, among other variables. The fission-barrier height of ^{239}U has been determined via the ^{238}U(d,pf) reaction in inverse kinematics, the results of which are consistent with existing neutron-induced fission data indicating the validity of the technique.
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Affiliation(s)
- S A Bennett
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
| | - K Garrett
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
| | - D K Sharp
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
| | - S J Freeman
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
- CERN, CH-1211 Geneva 23, Switzerland
| | - A G Smith
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
| | - T J Wright
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
| | - B P Kay
- Physics Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - T L Tang
- Physics Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - I A Tolstukhin
- Physics Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Y Ayyad
- IGFAE, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - J Chen
- Physics Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - P J Davies
- School of Physics, Engineering and Technology, University of York, Heslington, York YO10 5DD, United Kingdom
| | - A Dolan
- Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - L P Gaffney
- Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - A Heinz
- Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - C R Hoffman
- Physics Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - C Müller-Gatermann
- Physics Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - R D Page
- Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - G L Wilson
- Physics Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
- Louisiana State University, Baton Rouge, Louisiana 70803, USA
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2
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Ren ZX, Vretenar D, Nikšić T, Zhao PW, Zhao J, Meng J. Dynamical Synthesis of ^{4}He in the Scission Phase of Nuclear Fission. PHYSICAL REVIEW LETTERS 2022; 128:172501. [PMID: 35570452 DOI: 10.1103/physrevlett.128.172501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/11/2022] [Accepted: 04/08/2022] [Indexed: 06/15/2023]
Abstract
In the exothermic process of fission decay, an atomic nucleus splits into two or more independent fragments. Several aspects of nuclear fission are not properly understood, in particular the formation of the neck between the nascent fragments, and the subsequent mechanism of scission into two or more independent fragments. Using an implementation of time-dependent density functional theory, based on a relativistic energy density functional and including pairing correlations, we analyze the final phase of the process of induced fission of ^{240}Pu, and show that the timescale of neck formation coincides with the assembly of two α-like clusters. Because of its much larger binding energy, the dynamical synthesis of ^{4}He in the neck predominates over other light clusters, e.g., ^{3}H and ^{6}He. At the instant of scission the neck ruptures exactly between the two α-like clusters, which separate because of the Coulomb repulsion and are eventually absorbed by the two emerging fragments. The mechanism of light charged clusters formation at scission could also be linked to ternary fission.
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Affiliation(s)
- Z X Ren
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
| | - D Vretenar
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
- Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
| | - T Nikšić
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
- Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
| | - P W Zhao
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
| | - J Zhao
- Center for Circuits and Systems, Peng Cheng Laboratory, Shenzhen 518055, China
| | - J Meng
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
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3
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Bulgac A, Abdurrahman I, Godbey K, Stetcu I. Fragment Intrinsic Spins and Fragments' Relative Orbital Angular Momentum in Nuclear Fission. PHYSICAL REVIEW LETTERS 2022; 128:022501. [PMID: 35089747 DOI: 10.1103/physrevlett.128.022501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/16/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023]
Abstract
We present the first fully unrestricted microscopic calculations of the primary fission fragment intrinsic spins and of the fission fragments' relative orbital angular momentum for ^{236}U^{*}, ^{240}Pu^{*}, and ^{252}Cf using the time-dependent density functional theory framework. Within this microscopic approach, free of restrictions and unchecked assumptions and which incorporates the relevant physical observables for describing fission, we evaluate the triple distribution of the fission fragment intrinsic spins and of their fission fragments' relative orbital angular momentum and show that their dynamics is dominated by their bending collective modes in contradistinction to the predictions of the existing phenomenological models and some interpretations of experimental data.
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Affiliation(s)
- Aurel Bulgac
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Ibrahim Abdurrahman
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Kyle Godbey
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
| | - Ionel Stetcu
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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4
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Schmitt C, Lemasson A, Schmidt KH, Jhingan A, Biswas S, Kim YH, Ramos D, Andreyev AN, Curien D, Ciemala M, Clément E, Dorvaux O, De Canditiis B, Didierjean F, Duchêne G, Dudouet J, Frankland J, Jacquot B, Raison C, Ralet D, Retailleau BM, Stuttgé L, Tsekhanovich I. Experimental Evidence for Common Driving Effects in Low-Energy Fission from Sublead to Actinides. PHYSICAL REVIEW LETTERS 2021; 126:132502. [PMID: 33861122 DOI: 10.1103/physrevlett.126.132502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 10/22/2020] [Accepted: 02/25/2021] [Indexed: 06/12/2023]
Abstract
Isotopic distributions of fragments from fission of the neutron-deficient ^{178}Hg nuclide are reported. This experimental observable is obtained for the first time in the region around lead using an innovative approach based on inverse kinematics and the coincidence between the large acceptance magnetic spectrometer VAMOS++ and a new detection arm close to the target. The average fragment N/Z ratio and prompt neutron M_{n} multiplicity are derived and compared with current knowledge from actinide fission. A striking consistency emerges, revealing the unexpected dominant role of the proton subsystem with atomic number between the Z=28 and 50 magic numbers. The origin of nuclear charge polarization in fission and fragment deformation at scission are discussed.
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Affiliation(s)
- C Schmitt
- Institut Pluridisciplinaire Hubert Curien, CNRS/IN2P3-UDS, 67037 Strasbourg Cedex 2, France
| | - A Lemasson
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, 14076 Caen cedex 5, France
| | | | - A Jhingan
- Inter University Accelerator Centre, Aruna Asaf Ali Marg, Post Box 10502, New Delhi 110067, India
| | - S Biswas
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, 14076 Caen cedex 5, France
| | - Y H Kim
- Institut Laue-Langevin, 38042 Grenoble Cedex 9, France
| | - D Ramos
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, 14076 Caen cedex 5, France
| | - A N Andreyev
- Department of Physics, University of York, York YO10 5DD, United Kingdom
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
- ISOLDE, CERN, CH-1211 Geneve 23, Switzerland
| | - D Curien
- Institut Pluridisciplinaire Hubert Curien, CNRS/IN2P3-UDS, 67037 Strasbourg Cedex 2, France
| | - M Ciemala
- The Niewodniczanski Institute of Nuclear Physics-PAN, 31-342 Kraków, Poland
| | - E Clément
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, 14076 Caen cedex 5, France
| | - O Dorvaux
- Institut Pluridisciplinaire Hubert Curien, CNRS/IN2P3-UDS, 67037 Strasbourg Cedex 2, France
| | - B De Canditiis
- Institut Pluridisciplinaire Hubert Curien, CNRS/IN2P3-UDS, 67037 Strasbourg Cedex 2, France
| | - F Didierjean
- Institut Pluridisciplinaire Hubert Curien, CNRS/IN2P3-UDS, 67037 Strasbourg Cedex 2, France
| | - G Duchêne
- Institut Pluridisciplinaire Hubert Curien, CNRS/IN2P3-UDS, 67037 Strasbourg Cedex 2, France
| | - J Dudouet
- CSNSM, Université Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, 91405 Orsay, France
- Université Lyon, Université Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, F-69622 Villeurbanne, France
| | - J Frankland
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, 14076 Caen cedex 5, France
| | - B Jacquot
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, 14076 Caen cedex 5, France
| | - C Raison
- Department of Physics, University of York, York YO10 5DD, United Kingdom
| | - D Ralet
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, 14076 Caen cedex 5, France
| | - B-M Retailleau
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, 14076 Caen cedex 5, France
| | - L Stuttgé
- Université Lyon, Université Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, F-69622 Villeurbanne, France
| | - I Tsekhanovich
- Université Bordeaux, CNRS, CENBG, UMR 5797, F-33170 Gradignan, France
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5
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Mirea M. Microscopic description of α-decay as super-asymmetric fission. EPJ WEB OF CONFERENCES 2021. [DOI: 10.1051/epjconf/202125600010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The fine structure of α-decay is treated with fission-like models. The single particle levels are calculated along a least action path connecting the ground state of the parent nucleus and the configuration of two spherical tangent nuclei. The probabilities to find different seniority-1 configurations are obtaining by solving the time-dependent pairing equations generalized by including the Landau-Zener effect and the Coriolis coupling. The theoretical results for the α-decay of 211Po and 211Bi are compared with experimental data showing a good agreement.
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6
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Schmidt KH, Estienne M, Fallot M, Jurado B, Schmitt C. Structural effects in the production of neutrons, gammas and anti-neutrinos in fission. EPJ WEB OF CONFERENCES 2021. [DOI: 10.1051/epjconf/202125600015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Structural effects in the production of light particles in fission are investigated. Most of these effects can be traced back to pairing correlations and shell effects and their dependencies on the composition of the fissioning system and its excitation energy. It is shown that the GEF code is able to reproduce most of these features and to explain their origin on the basis of established properties of nuclear matter as well as concepts and laws of general validity. Predictions for systems with scarce or no experimental information can also be made.
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7
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Marević P, Schunck N. Fission of ^{240}Pu with Symmetry-Restored Density Functional Theory. PHYSICAL REVIEW LETTERS 2020; 125:102504. [PMID: 32955318 DOI: 10.1103/physrevlett.125.102504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 06/09/2020] [Accepted: 07/29/2020] [Indexed: 06/11/2023]
Abstract
Nuclear fission plays an important role in fundamental and applied science, from astrophysics to nuclear engineering, yet it remains a major challenge to nuclear theory. Theoretical methods used so far to compute fission observables rely on symmetry-breaking schemes where basic information on the number of particles, angular momentum, and parity of the fissioning nucleus is lost. In this Letter, we analyze the impact of restoring broken symmetries in the benchmark case of ^{240}Pu.
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Affiliation(s)
- P Marević
- Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - N Schunck
- Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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8
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Bertulani CA, Kucuk Y, Lozeva R. Fission of Relativistic Nuclei with Fragment Excitation and Reorientation. PHYSICAL REVIEW LETTERS 2020; 124:132301. [PMID: 32302156 DOI: 10.1103/physrevlett.124.132301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/19/2020] [Accepted: 03/09/2020] [Indexed: 06/11/2023]
Abstract
Experimental studies of fission induced in relativistic nuclear collisions show a systematic enhancement of the excitation energy of the primary fragments by a factor of ∼2, before their decay by fission and other secondary fragments. Although it is widely accepted that by doubling the energies of the single-particle states may yield a better agreement with fission data, it does not prove fully successful, since it is not able to explain yields for light and intermediate mass fragments. State-of-the-art calculations are successful to describe the overall shape of the mass distribution of fragments, but fail within a factor of 2-10 for a large number of individual yields. Here, we present a novel approach that provides an account of the additional excitation of primary fragments due to final state interaction with the target. Our method is applied to the ^{238}U+^{208}Pb reaction at 1 GeV/nucleon (and is applicable to other energies), an archetype case of fission studies with relativistic heavy ions, where we find that the large probability of energy absorption through final state excitation of giant resonances in the fragments can substantially modify the isotopic distribution of final fragments in a better agreement with data. Finally, we demonstrate that large angular momentum transfers to the projectile and to the primary fragments via the same mechanism imply the need of more elaborate theoretical methods than the presently existing ones.
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Affiliation(s)
- Carlos A Bertulani
- Department of Physics and Astromomy, Texas A&M University-Commerce, Commerce, Texas 75429, USA
| | - Yasemin Kucuk
- Akdeniz University, Science Faculty, Department of Physics, Antalya 07058, Turkey
| | - Radomira Lozeva
- Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay 91405, France
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9
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Siefman D, Hursin M, Sjostrand H, Schnabel G, Rochman D, Pautz A. Data assimilation of post-irradiation examination data for fission yields from GEF. EPJ NUCLEAR SCIENCES & TECHNOLOGIES 2020. [DOI: 10.1051/epjn/2020015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nuclear data, especially fission yields, create uncertainties in the predicted concentrations of fission products in spent fuel which can exceed engineering target accuracies. Herein, we present a new framework that extends data assimilation methods to burnup simulations by using post-irradiation examination experiments. The adjusted fission yields lowered the bias and reduced the uncertainty of the simulations. Our approach adjusts the model parameters of the code GEF. We compare the BFMC and MOCABA approaches to data assimilation, focusing especially on the effects of the non-normality of GEF’s fission yields. In the application that we present, the best data assimilation framework decreased the average bias of the simulations from 26% to 14%. The average relative standard deviation decreased from 21% to 14%. The GEF fission yields after data assimilation agreed better with those in JEFF3.3. For Pu-239 thermal fission, the average relative difference from JEFF3.3 was 16% before data assimilation and after it was 12%. For the standard deviations of the fission yields, GEF’s were 100% larger than JEFF3.3’s before data assimilation and after were only 4% larger. The inconsistency of the integral data had an important effect on MOCABA, as shown with the Marginal Likelihood Optimization method. When the method was not applied, MOCABA’s adjusted fission yields worsened the bias of the simulations by 30%. BFMC showed that it inherently accounted for this inconsistency. Applying Marginal Likelihood Optimization with BFMC gave a 2% lower bias compared to not applying it, but the results were more poorly converged.
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10
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Siefman D, Hursin M, Pautz A. Data assimilation of post irradiation examination experiments to adjust fission yields. EPJ WEB OF CONFERENCES 2020. [DOI: 10.1051/epjconf/202023913004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nuclear data, especially fission yields, create uncertainties in the predicted concentrations of fission products in spent fuel. Herein, we present a new framework that extends data assimilation methods to burnup simulations by using data from post-irradiation examination experiments. The adjusted fission yields improve the bias and reduce the uncertainty of predicted fission product concentrations in spent fuel. Our approach modifies fission yields by adjusting the model parameters of the code GEF with post-irradiation examination experiments. We used the BFMC data assimilation method to account for the non-normality of GEF's fission yields. In the application that we present, the assimilation decreased the average bias of the predicted fission product concentrations from 26% to 15%. The average relative standard deviation decreased from 21% to 14%. The GEF fission yields after data assimilation agreed better with those in ENDF/B-VIII.O. For Pu-239 thermal fission, the average relative difference from ENDF/B-VIII.O was 16% before data assimilation and 11% after. For the standard deviations of the fission yields, GEF's were, on average, 16% larger than those from ENDF/B-VIII.O before data assimilation and 15% smaller after.
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11
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Wang ZA, Pei J, Liu Y, Qiang Y. Bayesian Evaluation of Incomplete Fission Yields. PHYSICAL REVIEW LETTERS 2019; 123:122501. [PMID: 31633953 DOI: 10.1103/physrevlett.123.122501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 07/16/2019] [Indexed: 06/10/2023]
Abstract
Fission product yields are key infrastructure data for nuclear applications in many aspects. It is a challenge both experimentally and theoretically to obtain accurate and complete energy-dependent fission yields. We apply the Bayesian neural network (BNN) approach to learn existing fission yields and predict unknowns with uncertainty quantification. We demonstrated that the BNN is particularly useful for evaluations of fission yields when incomplete experimental data are available. The BNN evaluation results are quite satisfactory on distribution positions and energy dependencies of fission yields.
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Affiliation(s)
- Zi-Ao Wang
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
| | - Junchen Pei
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
| | - Yue Liu
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
| | - Yu Qiang
- State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
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12
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Ramos D, Caamaño M, Lemasson A, Rejmund M, Audouin L, Álvarez-Pol H, Frankland JD, Fernández-Domínguez B, Galiana-Baldó E, Piot J, Ackermann D, Biswas S, Clement E, Durand D, Farget F, Fregeau MO, Galaviz D, Heinz A, Henriques AI, Jacquot B, Jurado B, Kim YH, Morfouace P, Ralet D, Roger T, Schmitt C, Teubig P, Tsekhanovich I. First Direct Measurement of Isotopic Fission-Fragment Yields of ^{239}U. PHYSICAL REVIEW LETTERS 2019; 123:092503. [PMID: 31524478 DOI: 10.1103/physrevlett.123.092503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Indexed: 06/10/2023]
Abstract
A direct and complete measurement of isotopic fission-fragment yields of ^{239}U has been performed for the first time. The ^{239}U fissioning system was produced with an average excitation energy of 8.3 MeV in one-neutron transfer reactions between a ^{238}U beam and a ^{9}Be target at Coulomb barrier energies. The fission fragments were detected and isotopically identified using the VAMOS++ spectrometer at the GANIL facility. The measurement allows us to directly evaluate the fission models at excitation energies of fast neutrons, which are relevant for next-generation nuclear reactors. The present data, in agreement with model calculations, do not support the recently reported anomaly in the fission-fragment yields of ^{239}U, and they confirm the persistence of spherical shell effects in the Sn region at excitation energies exceeding the fission barrier by a few mega-electron volts.
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Affiliation(s)
- D Ramos
- IPN Orsay, Université de Paris-Saclay, CNRS/IN2P3, F-91406 Orsay Cedex, France
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - M Caamaño
- IGFAE, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Spain
| | - A Lemasson
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - M Rejmund
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - L Audouin
- IPN Orsay, Université de Paris-Saclay, CNRS/IN2P3, F-91406 Orsay Cedex, France
| | - H Álvarez-Pol
- IGFAE, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Spain
| | - J D Frankland
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - B Fernández-Domínguez
- IGFAE, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Spain
| | - E Galiana-Baldó
- IGFAE, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Spain
- LIP Lisboa, 1649-003 Lisbon, Portugal
| | - J Piot
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - D Ackermann
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - S Biswas
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - E Clement
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - D Durand
- LPC Caen, Université de Caen Basse-Normandie-ENSICAEN-CNRS/IN2P3, F-14050 Caen Cedex, France
| | - F Farget
- LPC Caen, Université de Caen Basse-Normandie-ENSICAEN-CNRS/IN2P3, F-14050 Caen Cedex, France
| | - M O Fregeau
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - D Galaviz
- LIP Lisboa, 1649-003 Lisbon, Portugal
| | - A Heinz
- Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - A I Henriques
- CENBG, IN2P3/CNRS-Université de Bordeaux, F-33175 Gradignan Cedex, France
| | - B Jacquot
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - B Jurado
- CENBG, IN2P3/CNRS-Université de Bordeaux, F-33175 Gradignan Cedex, France
| | - Y H Kim
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - P Morfouace
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - D Ralet
- CSNSM, CNRS/IN2P3, Université de Paris-Saclay, F-91405 Orsay, France
| | - T Roger
- GANIL, CEA/DRF-CNRS/IN2P3, BP 55027, F-14076 Caen Cedex 5, France
| | - C Schmitt
- IPHC Strasbourg, Université de Strasbourg-CNRS/IN2P3, F-67037 Strasbourg Cedex 2, France
| | - P Teubig
- LIP Lisboa, 1649-003 Lisbon, Portugal
| | - I Tsekhanovich
- CENBG, IN2P3/CNRS-Université de Bordeaux, F-33175 Gradignan Cedex, France
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13
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Abstract
Abstract
Recent progress in the production of heavy nuclei far from stability and in the studies of nuclear and chemical properties of heavy actinides is briefly reviewed. Exotic nuclear decay properties including nuclear fission of heavy nuclei, measurements of first ionization potentials of heavy actinides, and redox studies of heavy actinides are described. Brief history of discovery of the transuranium elements is also presented.
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Affiliation(s)
- Yuichiro Nagame
- Advanced Science Research Center, Japan Atomic Energy Agency (JAEA) , Tokai-mura, Ibaraki 319-1195 , Japan
- Graduate School of Science and Engineering , Ibaraki University , Mito, Ibaraki 310-8512 , Japan
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Impact of pear-shaped fission fragments on mass-asymmetric fission in actinides. Nature 2018; 564:382-385. [PMID: 30568195 DOI: 10.1038/s41586-018-0780-0] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 10/31/2018] [Indexed: 11/08/2022]
Abstract
Nuclear fission of heavy (actinide) nuclei results predominantly in asymmetric mass splits1. Without quantum shell effects, which can give extra binding energy to their mass-asymmetric shapes, these nuclei would fission symmetrically. The strongest shell effects appear in spherical nuclei, such as the spherical 'doubly magic' (that is, both its atomic and neutron numbers are 'magic' numbers) nucleus 132Sn, which contains 50 protons and 82 neutrons. However, a systematic study of fission2 has shown that heavy fission fragments have atomic numbers distributed around Z = 52 to Z = 56, indicating that the strong shell effects in 132Sn are not the only factor affecting actinide fission. Reconciling the strong spherical shell effects at Z = 50 with the different Z values of fission fragments observed in nature has been a longstanding puzzle3. Here we show that the final mass asymmetry of the fragments is also determined by the extra stability provided by octupole (pear-shaped) deformations, which have been recently confirmed experimentally around 144Ba (Z = 56)4,5, one of very few nuclei with shell-stabilized octupole deformation6. Using a quantum many-body model of superfluid fission dynamics7, we find that heavy fission fragments are produced predominantly with 52 to 56 protons, which is associated with substantial octupole deformation acquired on the way to fission. These octupole shapes, which favour asymmetric fission, are induced by deformed shells at Z = 52 and Z = 56. By contrast, spherical magic nuclei are very resistant to octupole deformation, which hinders their production as fission fragments. These findings may explain surprising observations of asymmetric fission in nuclei lighter than lead8.
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