Article
Physics, Nuclear
Kang Wei, Hong-Fei Zhang, Zhi-Xuan He, Xing-Yu Wang, Shu-Qin Guo, Bi-Tao Hu
Summary: By exploiting the concept of the dinuclear system, this study analyzed the interaction potential energy of close fragments using a semi-classical method and simplified two-dimensional model. The results reproduced the fission fragment distributions well, including recent experimental data, indicating the usefulness of the simplified model for global measurements of fission products.
Article
Astronomy & Astrophysics
V. Yu. Denisov, I. Yu. Sedykh
Summary: The dependence of the average total kinetic energy of fission fragments on the excitation energy of the fissioning system is obtained in a simple model, and it is well described by experimental data for U-234, U-236, U-239, and Pu-240 nuclei. The origin of this energy dependence is discussed in detail in the study.
Article
Astronomy & Astrophysics
V. Piau, O. Litaize, A. Chebboubi, S. Oberstedt, A. Gook, A. Oberstedt
Summary: Monte-Carlo simulations using the FIFRELIN code were performed to reproduce the neutron and gamma-ray multiplicity distributions as a function of the pre-neutron mass of the fission fragments. A consistent set of parameters, including an energy-dependent spin cut-off model and microscopic level densities from the HFB plus combinatorial method, was used. The study also examines the relationship between initial excitation-energy sharing and TKE-dependent gamma-ray multiplicity.
Article
Physics, Nuclear
Amandeep Kaur, Nitin Sharma, Manoj K. Sharma
Summary: The analysis of even mass Fm242-260 isotopes using a preformed cluster model based on quantum mechanical fragmentation theory reveals differences in fission fragment mass distributions under different deformation configurations, with discrepancies in the calculated SF half-lives compared to experimental data.
Article
Physics, Nuclear
Li-Le Liu, Xi-Zhen Wu, Yong-Jing Chen, Cai-Wan Shen, Zhu-Xia Li, Zhi-Gang Ge, Neng-Chuan Shu
Summary: In this study, the influence of the neck parameter on the fission dynamics at low excitation energy was investigated. It was found that the neck parameter has a strong impact on the total kinetic energy distribution of the fragments, while it has almost no obvious effect on the fragment mass distribution. The calculated post-neutron emission fragment mass distributions are in good agreement with the experimental data, with the results for ? = 0.35 showing the best agreement.
Article
Physics, Nuclear
Pavel Kostryukov, Artur Dobrowolski, Bozena Nerlo-Pomorska, Michal Warda, Zhigang Xiao, Yongjing Chen, Lile Liu, Jun-Long Tian, Krzysztof Pomorski
Summary: In this study, potential energy surfaces and fission barriers of superheavy nuclei were analyzed using a macroscopic-microscopic model. The Fourier shape parametrization with three deformation parameters effectively reproduced nuclear shapes and predicted a new highly asymmetric fission mode in most superheavy nuclei. The fission fragment mass distributions of the considered nuclei were obtained by solving 3D Langevin equations.
Article
Instruments & Instrumentation
S. Marina, I. A. Tolstukhin, N. P. Giha, M. B. Oberling, R. A. Knaack, B. P. Kay, D. L. Duke, K. B. Montoya, D. Connolly, W. Loveland, A. Chemey, S. A. Pozzi, F. Tovesson
Summary: Recent theoretical and experimental results have sparked renewed interest in fission fragment angular momentum. Neutron and γ-ray measurements in conjunction with fission fragments are still the most valuable tools for studying fission physics. In this study, a new twin Frisch-gridded ionization chamber and an array of trans-stilbene organic scintillators (FS-3) were developed for measuring fission fragment properties and neutron/y-ray multiplicities and spectra. The details of these detectors and the initial experimental results are discussed, as well as future plans for event-by-event analysis and experiments.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
(2023)
Article
Nuclear Science & Technology
Kazuki Fujio, Shin Okumura, Chikako Ishizuka, Satoshi Chiba, Tatsuya Katabuchi
Summary: Researchers have developed a novel theoretical method to obtain independent fission product yields and prompt neutron observables. This method has the potential to prepare fission-related nuclear data for nuclides for which measurements are difficult.
JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
(2023)
Review
Physics, Multidisciplinary
S. Leoni, C. Michelagnoli, J. N. Wilson
Summary: The paper reviews recent developments in gamma-ray spectroscopy of the neutron-rich fragments produced in nuclear fission. It highlights key results and describes the evolution of experimental techniques since the last review papers in 1995. It explores research themes in nuclear structure, the fission reaction mechanism, and the links to nuclear astrophysics and applications.
RIVISTA DEL NUOVO CIMENTO
(2022)
Article
Physics, Nuclear
J. H. Chi, Y. Qiang, C. Y. Gao, J. C. Pei
Summary: In this work, the authors implemented multipole deformation-constrained Skyrme Hartree-Fock+BCS (SHF-BCS) calculations to obtain microscopic multi-dimensional potential energy surfaces for the fission of 240Pu. The results revealed the importance of hexadecapole deformation at large deformations, which is related to issues of multiple solutions and discontinuities in potential energy surfaces. By introducing a suitable disturbance of hexadecapole deformation /34, a smooth 2-dimensional potential energy surface in (/32, /33) can be obtained through parallel calculations. Additionally, constrained SHF-BCS calculations in the 3-dimensional deformation space of (/32, /33, /34) were developed.
Article
Physics, Nuclear
A. Gaamouci, I Dedes, J. Dudek, A. Baran, N. Benhamouda, D. Curien, H. L. Wang, J. Yang
Summary: The study involves mean-field calculations in multidimensional deformation spaces to address shape coexistence and isomers generated by exotic nuclear configurations. A phenomenological mean-field Hamiltonian of Woods-Saxon type with universal parametrization was used, and original parametric correlations were removed using inverse problem theory methods. Stochastic analysis of uncertainties in final nuclear energy predictions with the correlation-free parametrization was conducted, and experimental verification of predicted exotic structures was encouraged.
Article
Physics, Multidisciplinary
Kazuki Fujio, Shuichiro Ebata, Tsunenori Inakura, Chikako Ishizuka, Satoshi Chiba
Summary: This study examined the fission barrier of U-236 using a microscopic mean-field model and found that the results were consistent with the trend of overestimation commonly observed in previous calculations. Furthermore, the study investigated the effects of spin-orbit and pairing terms on the fine structure of the fission barrier as well as the sensitivity of the barrier height to pairing strength.
FRONTIERS IN PHYSICS
(2022)
Article
Astronomy & Astrophysics
M. Guttormsen, Y. Alhassid, W. Ryssens, K. O. Ay, M. Ozgur, E. Algin, A. C. Larsen, F. L. Bello Garrote, L. Crespo Campo, T. Dahl-Jacobsen, A. Gorgen, T. W. Hagen, V. W. Ingeberg, B. V. Kheswa, M. Klintefjord, J. E. Midtbo, V. Modamio, T. Renstrom, E. Sahin, S. Siem, G. M. Tveten, F. Zeiser
Summary: By measuring nuclear level densities for a chain of neodymium isotopes, researchers observe a strong increase in level densities along the chain, with saturation around mass 150. The experimental and theoretical findings provide an explanation for the observed mass dependence of the level densities.
Article
Physics, Nuclear
Aniruddha Dey, D. C. Biswas, A. Chakraborty, S. Mukhopadhyay, A. K. Mondal, L. S. Danu, B. Mukherjee, S. Garg, B. Maheshwari, A. K. Jain, A. Blanc, G. de France, M. Jentschel, U. Koster, S. Leoni, P. Mutti, G. Simpson, T. Soldner, C. A. Ur, W. Urban
Summary: A detailed investigation has been carried out for the relative isotopic distributions of even-even correlated fission fragments in the U-235(n, f) fission reaction, using high-statistics data obtained during the EXILL campaign at ILL, Grenoble, France. The experimental results have been substantiated by theoretical calculations and calculations based on the semiempirical GEF model, showing fair agreement between the results.
Article
Physics, Multidisciplinary
E. Ummukulsu, Antony Joseph
Summary: This study calculates the effective and collective level density of thorium nuclei within the mass range of 204-280, using a phenomenological model. The level density parameter decreases at neutron numbers N = 126 and 184, suggesting they could be neutron magic numbers. This research is crucial for understanding nuclear reactions under extreme conditions and includes an analysis of the shape and deformation of thorium nuclei.
INDIAN JOURNAL OF PHYSICS
(2023)
Article
Physics, Nuclear
R. Rodriguez-Guzman, L. M. Robledo, K. Nomura, N. Cruz Hernandez
Summary: The impact of quadrupole and octupole collectivity in the dynamics of low-lying collective states is discussed for Xe, Ba, Ce, and Nd isotopes. The results suggest that the coupling between quadrupole and octupole degrees of freedom is weak, and the properties of negative parity states can be reasonably described in terms of the octupole degree of freedom alone.
JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS
(2022)
Article
Computer Science, Interdisciplinary Applications
P. Marevic, N. Schunck, E. M. Ney, R. Navarro Perez, M. Verriere, J. O'Neal
Summary: We describe the new version 4.0 of the HFBTHO code, which introduces new capabilities and improvements for solving the nuclear Hartree-Fock-Bogoliubov problem. The new version implements the restoration of rotational, particle number, and reflection symmetry for even even nuclei, and also improves the calculation of the SeaLL1 functional and the Coulomb potential. The code has been refactored to enhance maintainability and facilitate future developments.
COMPUTER PHYSICS COMMUNICATIONS
(2022)
Review
Physics, Nuclear
Nicolas Schunck, David Regnier
Summary: Atomic nuclei are systems composed of protons and neutrons held together by strong nuclear forces. Nuclear fission is a phenomenon where nuclei can break into fragments and decay by emitting particles. Understanding this complex process is crucial for studying atomic nuclei.
PROGRESS IN PARTICLE AND NUCLEAR PHYSICS
(2022)
Article
Astronomy & Astrophysics
Rodrigo Navarro Perez, Nicolas Schunck
Summary: Predictions of nuclear properties far from measured data are inherently inaccurate due to uncertainties in nuclear forces and quantum many-body effects. Current approaches lose predictive power when input variables are far from the training region, resulting in uncontrolled uncertainties. This letter presents a new technique to identify input variables for machine learning algorithms that can provide robust estimates of model bias, improving theoretical predictions without increasing uncertainties.
Article
Physics, Multidisciplinary
Marc Verriere, Nicolas Schunck, Irene Kim, Petar Marevic, Kevin Quinlan, Michelle N. Ngo, David Regnier, Raphael David Lasseri
Summary: This paper reviews different approaches to applying machine learning and artificial intelligence techniques to nuclear density functional theory, with the aim of accelerating the generation of suitable DFT wavefunction basis.
FRONTIERS IN PHYSICS
(2022)
Article
Physics, Nuclear
R. Rodriguez-Guzman, L. M. Robledo
Summary: The emergence and stability of static octupole deformation in Dy isotopes are analyzed using mean-field and beyond-mean-field techniques. It is found that N ti 134 isotopes exhibit static octupole deformations while N ti 88 isotopes have reflection-symmetric ground states. However, neither of these levels of approximation is sufficient to determine the nature of octupole dynamics in Dy isotopes. The increased octupole collectivity in Dy isotopes with N ti 88 and N ti 134 is concluded to be vibrational in nature.
Review
Physics, Nuclear
M. Baldo, L. M. Robledo, X. Vinas
Summary: The foundation and applications of the Barcelona Catania Paris Madrid (BCPM) energy density functional are briefly reviewed. BCPM uses a paradigm more rooted on density functional theory and fits most of its parameters to sophisticated microscopic nuclear matter calculations. Finite nuclei are accounted for by introducing a direct finite range surface term, spin orbit potential, Coulomb interaction and pairing. Applications of this functional to the calculation of finite nuclei properties are presented as well as applications to the description of neutron star physics. The large number of applications discussed are possible because of the local character of the functional that simplifies enormously calculations in finite nuclei.
EUROPEAN PHYSICAL JOURNAL A
(2023)
Article
Physics, Nuclear
N. Schunck, M. Verriere, G. Potel Aguilar, R. C. Malone, J. A. Silano, A. P. D. Ramirez, A. P. Tonchev
Summary: Fission data are crucial for nucleosynthesis simulations and nuclear forensics. The characteristics of fission for odd-mass nuclei, as well as even-even nuclei, are important in various applications. Fission theories that aim at describing fission dynamics are usually based on nuclear mean-field theories. In this article, we use the blocking prescription of the Hartree-Fock-Bogoliubov theory with Skyrme energy functionals to investigate odd-mass uranium isotopes. Our results show that the fission fragment distributions depend significantly on the spin of the odd neutron. We propose a methodology based on the calculation of the spin distribution to predict the charge and mass distributions in odd-mass nuclei.
Article
Physics, Nuclear
R. Rodriguez-Guzman, L. M. Robledo, Carlos A. Jimenez-Hoyos, N. C. Hernandez
Summary: This study analyzes the impact of dynamic pairing correlations and their interplay with Coulomb antipairing effects on the systematic of the spontaneous fission half-lives for the nuclei 240-250Cm and 240-250Cf. The results show that considering the pairing degree of freedom significantly reduces the spontaneous fission half-lives, and the least action path is more consistent with the experiment than the least energy path.
Article
Physics, Nuclear
R. Rodriguez-Guzman, L. M. Robledo
Summary: The competition between Coulomb antipairing and restricted particle number symmetry restoration in a selected set of Fermium and Nobelium isotopes reveals that the Coulomb antipairing is partially compensated by beyond-mean-field pairing correlations. However, the compensation is not perfect, and the combined effect on fission dynamics cannot be overlooked.
Article
Optics
Javier Faba, Vicente Martin, Luis Robledo
Summary: In this paper, the performance of Hartree-Fock method and generator coordinate method in solving the quantum many-body problem for fermions is analyzed using the Lipkin model. It is found that these methods can reasonably well reproduce the exact ground state's quantum discord in certain partitions.
Article
Physics, Nuclear
L. M. Robledo
Summary: A recently developed formalism is used to perform generator coordinate method calculations with Hartree-Fock-Bogoliubov wave functions, where each member of the set can be expanded in an arbitrary basis. This paper assumes that the HFB wave functions are expanded in harmonic oscillator bases with different oscillator lengths. General expressions to compute the required matrix elements of arbitrary operators are provided. The application of this formalism in the case of fission is illustrated with an example.
Article
Physics, Multidisciplinary
Karolina Kolos, Vladimir Sobes, Ramona Vogt, Catherine E. Romano, Michael S. Smith, Lee A. Bernstein, David A. Brown, Mary T. Burkey, Yaron Danon, Mohamed A. Elsawi, Bethany L. Goldblum, Lawrence H. Heilbronn, Susan L. Hogle, Jesson Hutchinson, Ben Loer, Elizabeth A. McCutchan, Matthew R. Mumpower, Ellen M. O'Brien, Catherine Percher, Patrick N. Peplowski, Jennifer J. Ressler, Nicolas Schunck, Nicholas W. Thompson, Andrew S. Voyles, William Wieselquist, Michael Zerkle
Summary: Accurate nuclear data is crucial for advances in various fields, and outdated or incomplete data can hinder progress and compromise safety. Collaboration across organizations and international borders is essential in addressing the shared needs for nuclear data.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Nuclear
E. M. Ney, J. Engel, N. Schunck
Summary: In heavy nuclei, two-body weak currents have systematic effects on Gamow-Teller strength and beta-decay rates. The quenching effect of two-body currents decreases as the neutron excess increases, and they can enhance low-lying transitions. These effects are related to changes in total nucleon density.
Article
Physics, Nuclear
L. M. Robledo
Summary: The existing formalism for computing operator overlaps necessary for generator coordinate method calculations using Hartree-Fock-Bogoliubov wave functions is generalized to include different arbitrary bases spanning different subspaces of the Hilbert space.