Oliver C. Gorton

Postdoctoral Research Staff at Lawrence Livermore National Laboratory
Nuclear Data and Theory Group // Nuclear and Chemical Science Division

gorton3@llnl.gov
Github
Google Scholar
ORC ID: 0000-0003-3643-9640

On this page: Research interests, Research experience, Journal papers, Conference proceedings, Education, Awards, Codes, Contributed talks, Posters, Training and schools, Teaching

Research interests

I work on theoretical and computational methods of nuclear physics. My work follows the needs of nuclear astrophysics and nuclear technology, two fields which probe the limits of our understanding of matter in neutron-rich environments.

Nuclear structure and reactions: beta-delayed neutron emission, integration of nuclear shell-model and Hauser-Feshbach reaction theory.

Applications in related fields: the search for dark matter, nuclear data and evaluations, uncertainty quantification, machine learning, high-performance computing.

Research experience

• Postdoctoral Research Staff, Lawerence Livermore National Laboratory (April 2024 - present)
  • Developing shell model methods to improve nuclear structure and reaction theory of fission fragments and r-process nuclei
• LLNL ACT Scholar, Strategic Deterrence (2022 – 2024)
  • New predictive capability for reaction and decay properties of fission fragments
  • Defended PhD at LLNL
• Glenn T. Seaborg Institute (GTSI) Summer Intern, Seaborg Institute (Summer 2021)
• High Energy Density Physics Intern, Strategic Deterrence (Summer 2020)
• High Energy Density Physics Intern, Strategic Deterrence (Summer 2019)
• High Energy Density Physics Intern, Strategic Deterrence (Summer 2018)

Journal papers

• Towards shell model interactions with credible uncertainties
  O. C. Gorton and K. Kravvaris
  To be submitted (2025) | arXiv:2503.11889
• Weak entanglement approximation for nuclear structure
  O. C. Gorton and C. W. Johnson
  Physical Review C 110, 034305 (2024) | arXiv:2406.10120
• Proton-neutron entanglement in the nuclear shell model
  C. W. Johnson and O. C. Gorton
  Journal of Physics G: Nuclear and Particle Physics 50 (4) 045110 (2023) | arXiv:2210.14338
• dmscatter: A fast program for WIMP-nucleus scattering
  O. Gorton, C. Johnson, C. Jiao, J. Nikoleyczik
  Computer Physics Communications 284, 108597 (2023) | arXiv:2209.09187
• Cross sections for neutron-induced reactions from surrogate data: Reexamining the Weisskopf-Ewing approximation for (n,n’) and (n,2n) reactions
  O. C. Gorton and J. E. Escher
  Physical Review C: Nuclear Physics 107 (4), 044612 (2023) | arXiv:2102.03452
• Measurements of proton capture in the A=100-110 mass region: Constraints of the 111In(gamma,p)/(gamma,n) branching point relevant to the gamma-process
  O. Olivas-Gomez, A. Simon, O. Gorton, J. E. Escher et al. 
  Physical Review C: Nuclear Physics 102 (5), 055806 (2020)

Conference proceedings

• A weak entanglement approximation for nuclear structure: a progress report
  C. Johnson and O. Gorton
  Submitted to the proceedings of NTSE (Nuclear Theory in the Supercomputing Era) 2024 | arXiv:2504.00273
• Correcting for neutron width fluctuations in Hauser-Feshbach gamma branching ratios
  O. Gorton and J. Escher
  EPJ Web of Conferences 322, 02004 (2025) | arXiv:2410.01074
• Extending the Dispersive Optical Model to Beta-unstable Systems
  C. Pruitt, S. S. Perrotta, J. Escher, O. Gorton
  EPJ Web of Conferences 322, 05001 (2025)
• Towards next-generation optical potentials for nuclear reactions and structure calculations
  S. S. Perrotta, C. Priutt, O. Gorton, and J. Escher
  Nuclear Physics A 1057, 123037 (2025) | arXiv:2410.19269
• A Problem in the Statistical Description of Beta-Delayed Neutron Emission
  O. Gorton, C. Johnson, and J. Escher
  EPJ Web of Conferences 284, 03013 (2023) | arXiv:2210.05904
• Improving nuclear data evaluations with predictive reaction theory and indirect measurements
  J. Escher, K. Bergstrom, E. Chimanski, O. Gorton, E. J. In, M. Kruse, S. Peru, C. Pruitt, R. Rahman, E. Shinkle, A. Thapa, W. Younes
  EPJ Web of Conferences 284, 03012 (2023) | arXiv:2304:10034
• Neutron capture cross sections from surrogate reaction data and theory: connecting the pieces with a Markov-Chain Monte Carlo approach
  O. Gorton and J. E. Escher
  Springer Proceedings in Physics, vol 254, pages 229-231 (2021) | arXiv:1905:03055

Education

• Ph.D. Computational Science
  “Shell Model Methods, Statistical Nuclear Reactions, and Beta-delayed Neutron Emission”
  University of California, Irvine & San Diego State University joint doctoral program, 2024.
  Advisor: Calvin Johnson
• M.S. Physics
  “Efficient Modeling of Nuclei Through Coupling of Proton and Neutron Wavefunctions”
  San Diego State University, 2018. Advisor: Calvin Johnson
• B.A. Physics
  University of California, Berkeley, 2016

Awards and support

• LLNL SD Academic Collaboration Team University Program (ACT-UP) Award (2022, 2023, 2024)
  Full support, university tuition, travel funds, relocation to LLNL 8 mo./yr.
• Graduate “G-STEM” Scholarship (2018, 2019)
  National Science Foundation Program, awarded by Computational Science Research Center, San Diego State University
  Partial support and professional development training.

Codes

Languages: Modern Fortran, Python (numpy, scipy, MPI4py, multiprocessing, emcee), Bash, C++
Technologies: Experienced: MPI, openMP, git; Novice: CUDA, RAJA
Machines: Borax, Quartz in LC, LLNL facility

Primary developer of:

• dmscatter [Repository]
  A fast Fortran code for WIMP-nucleus form factors and differential event rate spectra. Modern Fortran with Python interface. OpenMP parallel.

• PANASh [Not yet released]
  Proton and neutron approximate shell model code providing advanced basis truncation scheme for nuclei away from stability. MPI and openMP hybrid parallel.

• COMMCAS [Not yet released]
  Computational Model Monte Carlo Sampler: Uncertainty quantification framework originally designed for Hauser-Feshbach statistical decay codes, now provides generic data-fitting, uncertainty quantification, and neural-network-emulation tools for physics codes. MPI and multiprocessing parallel.

• Wigner [Repository]
  A library of functions for computation of Wigner 3-j, 6-j and 9-j symbols, written in modern Fortran.

Contributed talks

• Is the USDB interaction unique?
  O. Gorton
  Talk at APS Global Physics Summit (Anaheim, March 2025)
  
• A weak entanglement approximation for nuclear structure
  O. Gorton and C. Johnson
  Talk at Shell Model Symposium: Celebrating 75 Years of the Nuclear Shell Model and Maria Goeppert-Mayer (Argonne National Lab., July 2024)
  
• Missing gammas: beta-delayed neutron emission of Rb-94
  O. Gorton, C. Johnson, J. Escher
  Talk at APS April 2024 Meeting (Sacramento, April 2024)
  
• Gamma-ray strength functions using approximate shell model calculations
  O. Gorton, C. Johnson, J. Escher
  Talk at T3 “Taking the Temperature” Workshop on Statistical Nuclear Physics for Astrophysics and Applications (Ohio University, August 2023)
• Nuclear Shell Model to the Rescue: Efforts to Resolve a Mystery in Beta Delayed Neutron Emission
  O. Gorton, C. Johnson, J. Escher
  Talk at APS Division of Nuclear Physics Fall 2022 Meeting (New Orleans, October 2022)
• Crisis in Beta-Delayed Neutron Emission: Shell Model to the Rescue
  O. Gorton, C. Johnson, J. Escher
  Talk at Nuclear Data Conference (Sacramento – virtual, July 2022)
• DMFortFactor: A Fast and Accessible for Computing WIMP-Nucleus-Scattering Event-Rates
  O. Gorton, C. Johnson, C. Jiao
  Talk at DNP21 APS Conference (Boston – virtual, October 2021)
• Better MCMC for Nuclear Data using emcee and B-DJINN
  O. C. Gorton, J. E. Escher, K. O. Bergstrom, M. K. Kruse
  Talk at LLNL Summer Slam (Livermore, August 2021)
• Nuclear Physics for WIMPs
  O. Gorton and C. W. Johnson
  Talk at SDSU SIAM Student Chapter Summer Colloquium Series, (San Diego, July 2021)
• Cross subsections for neutron reactions from surrogate measurements: Revisiting the Weisskopf-Ewing approximation
  O. Gorton and J. E. Escher
  Talk at DNP20 APS Conference (New Orleans – virtual, October 2020)
• Can we get rid of the theorists?
  O. Gorton and J. E. Escher
  Talk at LLNL Summer Slam (Livermore, August 2020)
• Big Picture and Background for Nuclear-Electronic Orbital (NEO) Approach: Calculating Mixed Nucleon-Electron Wave Functions
  O. Gorton
  Seminar for the Furche Group, Chemistry Department, UC Irvine (Irvine, March 2020)
• Indirect measurements of nuclear cross subsections: tempering experimental results with theory
  O. Gorton and J. E. Escher
  Seminar for HEDP Intern Exit Talk (Livermore, September 2019)
• A Markov Chain Monte Carlo Tool for Hauser-Feshbach Codes
  O. Gorton and J.E. Escher
  Seminar for HEDP Intern Exit Talk (Livermore, August 2018)

Posters

• Width Fluctuation Correction Factor for Beta-delayed Neutron Emission
  O. Gorton, J. Escher
  Poster at the 7th international workshop on Compound-Nuclear Reactions and Related Topics (Vienna, July 2024)
• Proton and Neutron Approximate Shell Model: Factorization-based Importance Truncation
  O. Gorton, C. Johnson, J. Escher
  Poster at Nuclear Structure Conference (Berkeley, June 2022)
• Sensitivity Study of the Surrogate Method
  O. Gorton and J. E. Escher
  Poster at LLNL Student Poster Symposium (Livermore, August 2019)
• Temperature and Entropy in the Nuclear Shell Model
  O. Gorton and C. W. Johnson
  Poster at SDSU ACCESS event (San Diego, April 2019)
• Proton Neutron Interacting Shell Model: Order of Magnitude Reduction for Medium Mass Nuclei
  O. Gorton and C. Johnson
  Poster at SDSU annual research symposium (San Diego, March 2019)
• Neutron capture cross subsections from surrogate reaction data and theory: connecting the pieces with a Markov-Chain Monte Carlo approach
  O. Gorton and J. E. Escher
  Poster at Compound Nuclear Reactions conference CNR18 (Berkeley, September 2018)

Training and schools

• Attended “FIESTA 2024” , Fission Experiments and Theoretical Advances (FIESTA) is a fission-focused school and workshop.
• Attended “FRIB-TA Summer School: A practical walk-through formal scattering theory”, 2021
  Lectures and hands on exercises in low-energy nuclear scattering theory
• Attended “Agile Development Practices and Tools: A Guided Tour”, 2020
  Collaborative source control using git, GitHub, and git workflows.
• Attended “Technical Writing Workshop” at LLNL, 2019

Teaching

• Graduate Teaching Associate for intro physics lab courses (2016 - 2020)
  San Diego State University, Department of Physics
  • Independently lead lectures and exams
  • Co-authored the department-wide manual for Physics 182A/195L Laboratory