Nuclear Reaction Theory for Astrophysics and Laboratory Applications

Project Overview

A predictive capability for inelastic scattering of neutrons and light, charged particles is needed for both basic and applied science. This project addresses this need by developing an integrated nuclear structure and reaction theory, along with the requisite codes, to enable predictive calculations for inelastic scattering from spherical and deformed medium-mass and heavy nuclei. The framework is built on a new quasiparticle random phase approximation (QRPA) code in a deformed basis and utilizes a modern coupled-channels direct-reaction description. Computational tools were developed to integrate this framework into modern evaluation efforts and surrogate-reaction calculations. The new capability lays the foundation for predicting inelastic scattering reactions for a variety of applications. It is expected that this advanced reaction approach will improve upon current treatments of inelastic neutron processes, which are poorly described by existing models, specifically those implemented in codes used for data evaluations. In addition, it will enable indirect measurements of nuclear reactions involving unstable nuclei.

Mission Impact

This project focused on multiple areas of nuclear theory relevant to basic science, thus supporting DOE's goal to deliver the scientific discoveries and tools that transform our understanding of nature and strengthen the connection between advances in fundamental science and technology innovation. The theory and codes developed as part of the project increase Lawrence Livermore National Laboratory's predictive capability in nuclear structure and reactions and enable indirect measurement of a large class of radioisotopes. This work supports the Laboratory's mission in nuclear weapons stockpile stewardship, its research challenge in nuclear weapons science, and its competency in nuclear, chemical, and isotopic science and technology. Both the technical developments and workforce training activities support the NNSA's goal to advance the science, technology, and engineering competencies that are the foundation of the NNSA mission.

Publications, Presentations, and Patents

O. Gorton, J. E. Escher, Cross sections for neutron-induced reactions from surrogate data: revisiting the Weisskopf-Ewing approximation for (n,n') and (n, 2n) reactions, arXiv.org:2102.03452 [nucl-th], (2021). LLNL-JRNL-819259.

Chimanski , E. V., et al. 2021 ."The São Paulo Potential and the 3 He Breakup Reaction at 130 MeV on 93 Nb and 197 Au." Brazilian Journal of Physics, 51, 323. LLNL-JRNL-815015.

Chimanski , E. V. and B. V. Carlson. 2021. "Nucleon-Induced Inelastic Scattering with Statistical Strength Functions and the ECIS Direct Reaction Code." The European Physical Journal A, 57. LLNL-JRNL-820989.

Chimanski , E. V., et al. 2021. "Modern Inelastic Scattering Descriptions for Nucleon Induced Reactions." Fluminense Federal University, Rio de Janeiro, Brazil. 10 March 2021. LLNL-ABS-820166.

Chimanski , E. V., et al. 2021. "Modern Inelastic Scattering Descriptions for Nuclear Data Evaluations, Nuclear Structure and Reaction Studies." NNDC - Brookhaven National Laboratory, Upton, NY, 8 August 2021. LLNL-ABS-823635.

Chimanski , E. V., et al. 2021. "Machine Learning Strategies for a Global Equation of State and a Better Description of Neutron Stars." XV Hadron Physics, 13-17 September 2021. LLNL-ABS-825897.

Chimanski , E. V., et al. 2021. "Modern Inelastic Scattering Descriptions: Deformed QRPA Excited State Transitions." Division of Nuclear Physics Fall Meeting, 11-14 October 2021. LLNL-ABS-823935.

Chimanski , E. V., et al. 2021. "Angular Momentum Restoration and One-Body Operators in the Quasi-Random-Phase Approximation: Nuclear Reactions and Nuclear Structure." Brazilian Nuclear Physics Meeting 2021, Brazil, 9-11 November 2021. LLNL-ABS-826181.

Lobato, R. V., et al. 2021. "Cluster Structures and Equation of State Properties in Neutron Stars with Machine Learning Support." Brazilian Nuclear Physics Meeting 2021, Brazil 9-11 November. LLNL-ABS-826180.

Chimanski , E. V., et al. 2021. "Nucleon-Induced Inelastic Scattering with Statistical Strength Functions and the ECIS Direct Reaction Code." The European Physical Journal A, 57. LLNL-JRNL-820989.

Souza, L. A., et al. 2021. "Inclusive Breakup Cross Sections in Reactions Induced by the Nuclides 6He and 6,7Li in the Two-Body Cluster Model." Physical Review C 2021. LLNL-JRNL-817859.

Chimanski , E. V. , et al. 2021 "Modern Inelastic Scattering Descriptions for Nucleon Induced Reactions." Fluminense Federal University, Rio de Janeiro, Brazil, 10 March 2021. LLNL-PRES-820331.

Chimanski , E. V. , et al. 2021 "Modern Inelastic Scattering Descriptions for Nuclear Data Evaluations, Nuclear Structure and Reaction Studies." NNDC - Brookhaven National Laboratory, Upton, NY, 8 August 2021. LLNL-PRES-825059.

Chimanski , E. V. , et al 2021."Machine Learning Strategies for a Global Equation of State and a Better Description of Neutron Stars." XV Hadron Physics, 13-17 September 2021. LLNL-PRES-826473.

Escher, J. E. 2021. "Advancing Our Understanding of Nuclear Reactions for Astrophysics and Applications." Invited seminar in the C2R2 Seminar Series, South Korea. LLNL-PRES-826220.

Bergstrom, K. O., et al. 2021. "Learning Nuclear Reaction Theory with DJINN." Lawrence Livermore National Laboratory. LLNL-PRES-826016.

O. Olivas-Gomez, et al, "Constraints of the 111In(gamma,p)/(gamma,n) Braching Point Relevant to the Gamma-Process." PRC 102, 055806 (2020), LLNL-JRNL-806081.

Mercenne, A., et al. 2020. "A New Ab Initio Approach for Nuclear Reactions Based on the Symmetry-adapted No-core Shell Model." GANIL Topical Meeting: Nuclear Structure and Reactions for the 2020s. LLNL-ABS-751669.

Gorton, O. C. and J. E. Escher. 2020. "Cross sections for neutron induced reactions from surrogate measurements: another examination of the Weisskopf-Ewing approximation." Division of Nuclear Physics Fall Meeting, 19 October - 1 November 2021. LLNL-ABS-811952.

Chimanski , E. V. , et al. 2020."Improving Inelastic Scattering Descriptions: Reaction Theory for Deformed Targets with the QRPA." Nuclear Structure, Santa Cruz, CA, 26-31 July 2020. LLNL-ABS-808038.

Chimanski , E. V. , et al. 2020. "Combining State-of-Art Nuclear Structure Theory with Modern Reaction Descriptions: Nucleon-Induced Reactions." Annual Meeting of the APS Far West Section, 9-10 October 2020. LLNL-ABS-814350.

Chimanski , E. V. , et al. 2020. "Improving Inelastic Scattering Descriptions: Reaction Theory for Deformed Targets with the QRPA." Division of Nuclear Physics Fall Meeting, 19 October - 1 November 2021. LLNL-ABS-812051.

Chimanski , E. V. , et al. 2020. "Nucleon Induced Reactions Theory for Deformed Target Nuclei: Angular Momentum Restoration and the QRPA." Brazilian Nuclear Physics Meeting, 14-16 December 2020. LLNL-ABS-815843.

Chimanski , E. V. , et al. 2020. "Inclusive Emissions from 3He Breakup Reaction on Medium and Heavy Targets." Brazilian Nuclear Physics Meeting, 14-16 December 2020. LLNL-ABS-815844.

Escher, J. E., 2020. "Nuclear Reaction Theory for Indirect Measurements of Neutron Capture and Other Reactions Involving Unstable Nuclei." University of Oslo. LLNL-ABS-795492.

Dreyfuss, A. C., et al. 2020. "Probing Alpha Clustering for X-ray Burst Nucleosynthesis in a Symmetry-Adapted Framework." Division of Nuclear Physics Fall Meeting, 19 October - 1 November 2021. LLNL-ABS-812034.

Dreyfuss, A. C., et al. 2020. "Probing Alpha-Clustering in 20Ne through Alpha+16O Within a Symmetry Adapted Framework." Physical Review C. LLNL-JRNL-810705.

Escher, J. E. 2020. "Surrogate Reactions: Doorways to Cross Sections for Unstable Isotopes." LLNL-ABS-811168.

Chimanski , E. V., et al. 2020."Extension of Nucleon-Induced Direct Reactions to Two Steps within the Multi-Step Direct Formalism." Physical Review C. LLNL-JRNL-814953.

Chimanski , E. V., et al. 2020. "Combining Modern Reaction Theory with State-of-the-Art Nuclear Structure Models." Federal University of Cariri, Brazil, 17 July 2020. LLNL-PRES-812599.

Chimanski , E. V., et al. 2020. "Combining State-of-Art Nuclear Structure Theory with Modern Reaction Descriptions: Nucleon Induced Reactions." 2020. Annual Meeting of the APS Far West Section, 9-10 October 2020. LLNL-PRES-815196.

Chimanski , E. V., et al. 2020. "Improving Inelastic Scattering Descriptions: Reaction Theory for Deformed Targets with the QRPA." Division of Nuclear Physics Fall Meeting, 19 October - 1 November 2021. LLNL-PRES-815994.

Chimanski , E. V., et al. 2020. "Nucleon Induced Reactions Theory for Deformed Target Nuclei: Angular Momentum Restoration and the QRPA." Brazilian Nuclear Physics Meeting, 14-16 December 2020. LLNL-PRES-817549.

Chimanski , E. V. , et al. 2020. "Inclusive Emissions from 3He Breakup Reaction on Medium and Heavy Targets." Brazilian Nuclear Physics Meeting, 14-16 December 2020. LLNL-PRES-817708.

Escher, J. E. 2020. "Nuclear Structure and Reaction Theory for FRIB Science." Invited talk at FRIB Day 1 Workshop. LLNL-PRES-809981.

Escher, J. E. 2020. "Surrogate Reactions: Doorways to Cross Sections for Unstable Isotopes." Invited talk at the Reaction Seminar Series hosted by INFN Sezione di Pisa, Italy. LLNL-PRES-811449.

Escher, J. E., 2020, "Nuclear Reaction Research for Astrophysics and Lab Applications." Invited talk at the LLNL Seaborg Institute. LLNL-PRES-813179.

Mercenne, A., et al. 2020. "Ab Initio Reactions for X-ray Burst Nucleosynthesis." DNP 2020 Fall Meeting. LLNL-PRES-816700.

Gorton, O. 2020. "Cross Sections for Neutron Reactions from Surrogate Measurements: Revisiting the Weisskopf-Ewing Approximation." DNP 2020 Fall Meeting, LLNL-PRES-816047.

Escher, J. E. 2020. "Advancing Nuclear Reaction Descriptions for Astrophysics and Applications." Colloquium at Louisiana State University. LLNL-PRES-817211.

Escher, J. E. 2020. "Stellar Burning: Capture Cross Sections for S-Process Branch Points from Indirect Data and Theory." JINA (Joint Institute for Nuclear Astrophysics) Horizons conference. LLNL-PRES-817100.

Escher, J. E., 2020, "Nuclear Reaction Descriptions for Astrophysics and Applications." Invited seminar at the Universities of Manchester and Liverpool. LLNL-PRES-817855.

Escher, J. E., 2019. "Cosmic Cauldrons and Exotic Nuclei: New Reaction Theory Developments for Determining Unknown Cross Sections." ASRC International Workshop Nuclear Fission and Structure of Exotic Nuclei Sakura 2019, Tokai, Japan, 25-27 March 2019. LLNL-ABS-765921.

Chimanski , E. V., et al. 2019. "Improved Inelastic Scattering Descriptions for Nuclear Data Evaluations, Nuclear Structure and Reaction Studies." Division of Nuclear Physics Fall Meeting, Crystal City, VA, 14-17 October 2019. LLNL-ABS-779840.

Gorton, O. and J. E. Escher. 2019. "Neutron Capture Cross Sections From Surrogate Reaction Data And Theory: Connecting The Pieces With a Markov-Chain Monte Carlo Approach." 6th International Workshop on Compound-Nuclear Reactions and Related Topics (CNR*18). LLNL-PROC773586.

Guerguiev, V. G., et al. 2019. "Neutron Transfer Reactions for Deformed Nuclei Using A Sturmian Basis." Compound Nuclear Reactions and Related Topics (CNR*18). LLNL-PROC765391.

Mercenne A., et al. 2019. "New Ab Initio Approach to Nuclear Reactions Based on the Symmetry-Adapted No-Core Shell Model." XXII International Conference on Few-Body Problems in Physics. LLNL-PROC763583.

Mercenne, A., et al. 2019. "New Symmetry-Adapted Ab Initio Approach to Nuclear Reactions for Intermediate Mass Nuclei." 6th International Workshop on Compound-Nuclear Reactions and Related Topics (CNR*18). LLNL-PROC767220.

Escher, J. E. 2019. "Nuclear Reaction Theory For the Era of Multimessenger Observations: Capture Cross Sections From Indirect Measurements, Nuclear and astrophysics aspects for the rapid neutron capture process in the era of multimessenger observations." LLNL-ABS-774252.

Escher, J. E., et al. 2019. "Surrogate Reaction Method for Neutron Capture and Other Reactions on Unstable Isotopes." 6th International Workshop on Compound-Nuclear Reactions and Related Topics (CNR*18). LLNL-PROC773585.

Escher, J. E. 2019. "Surrogate Reactions: Doorways to Cross Sections for Unstable Isotopes." 2019 International Conference on Nuclear Data for Science and Technology, Beijing, China, 19-24 May 2019. LLNL-ABS-762485.

Escher, J. E. 2019. "Surrogate Reactions: Doorways to Cross Sections for Unstable Isotopes." LLNL-ABS-766185.

Chimanski , E. V. , et al. 2019. "Improved Inelastic Scattering Descriptions for Nuclear Data Evaluations, Nuclear Structure and Reaction Studies." Division of Nuclear Physics Fall Meeting, Crystal City, VA, 14-17 October 2019. LLNL-PRES-792698.