H. Ratliff Consulting


Nuclear engineer & Expert radiation transport and nuclear activation modeler



Radiation transport simulations are an excellent tool for getting answers quickly and efficiently, saving time and resources compared to comparable explorative measurements. In design efforts (of experiments, radiation detectors, shielding, sources, etc.) they enable easy exploration of various ideas and their iterations, and simulations can be used to predict and validate real measured results too. They allow one to test the feasibility of and have confidence in a design/idea before committing the resources to building/executing it as well as providing extra confidence that the real observed results are trustworthy and as theory predicts they should be.

With an education and long background in nuclear engineering and armed with years of experience utilizing powerful radiation modeling tools, I seek to provide expert-informed, theoretically sound, and numerically supported solutions to a broad range of radiation-related challenges you may face.

I am an expert user and former developer of the PHITS general-purpose particle transport code, one of the major codes of its type with thousands of users worldwide at various academic, national lab, and industry locations. While working on the PHITS development team in Japan, I specifically led development and modernization of the DCHAIN-PHITS buildup, burnup, activation, and decay code coupled to PHITS.

PHITS can model and I have experience simulating scenarios including (but not limited to):

  • Dose rate determination in a given source and shielding scenario
  • Shielding design to achieve a desired dose distribution / maximum dose rate
  • Detector design, multi-hit coincident interaction detection, optimizing arrangement
  • Gamma-ray spectroscopy including detector resolution effects
  • Neutron time-of-flight measurements with various timing schemes
  • Gamma-ray transmission for determining material thickness/density
  • Materials activation: time-dependent nuclide inventories (+ activity and decay heat) of a sample/structure during and after irradiation with any irradiation schedule and source type
  • Activation dose rate distributions (and shielding & spectrocopy) from the resulting secondary radiation field produced by activated materials
  • High-energy ion beam experiments and secondary particle yields
  • Scintillator detector response function generation
  • Radiation therapy, using DICOM medical imaging files to model CT/PET/SPECT scans
  • Facility design, with electromagnetic fields for guiding/bending/focusing charged beams
  • Space radiation interactions (cosmic radiation, solar particle events)

This is by no means an exhaustive list. PHITS can model nearly any scenario one can imagine involving radiation traversing matter and track all physical quantities of interest, something I have taken advantage of extensively in my years of solving a large variety of challenges with it.

If you have any inquiries, please drop me a line at consulting@hratliff.com, and we can explore how I may be able to help with any radiation-related challenges you may face.