Area of research is computational modeling for low-energy physics in microscopically heterogeneous biological systems. Main focus is reducing the homogeneous approximations currently employed when predicting molecular structure perturbations to DNA and proteins via charged particle irradiation.


Special interests in low energy charged particle interactions with biological systems without using the principle of superposition.


Establishing of a Systems Radiobiology approach to radiation effects in complex biological systems.


Madsen, J. R., and G. Akabani. "Low-energy cross-section calculations of single molecules by electron impact: a classical Monte Carlo transport approach with quantum mechanical description." Physics in Medicine and Biology (Institute of Physics) 59, no. 9 (2014): 2285

Work Experience

Lecturer – “Introduction to Geant4 Monte Carlo Transport”

Spring 2013, Fall 2014

Texas A&M University, 3133 TAMU, College Station, TX, 77843

  • ​Primary instructor for nuclear engineering graduate-level class on Monte Carlo transport simulations using the GEANT4 toolkit

MCATK Project

May 2014 – August 2014
Los Alamos National Laboratory, Los Alamos, NM 87545

  • Implemented shared memory parallelism in Monte Carlo Applications Toolkit (MCATK) using Intel Thread Building Blocks (TBB)
  • Rewrote C++ STL deque to handle atomics

GEANT4 Collaboration
September 2011 - Present
CERN, CH-1211 Geneva 23 Switzerland
Low Energy Electromagnetic Physics Working Group
  • Developing Monte Carlo method for determining low energy cross-sections for charged particle transport through single molecules
  • Extensive Geant4 application development

Fall 2013 – Present
Texas A&M University, 3133 TAMU, College Station, TX, 77843
  • Fully Implicit Monte Carlo for Radiation Thermal Transport
  • Implemented shared memory parallelism using Intel Thread Building Blocks (TBB)
  • Real-time visualization via OpenGL
  • Improving code structure/design
  • Wrote build system with CMake

PDT Project

Summer 2011, Summer 2012, Summer 2013, August 2014 - Present

Texas A&M University, 3133 TAMU, College Station, TX, 77843

  • Parallel Deterministic Transport
  • Extensions to radiative transfer package
  • Wrote build system with CMake, benchmarked neutronics package with MCNP

Geant4 Subcontractor

September 2010 – July 2012

Transpire, Inc., 6659 Kimball Drive, Suite E502, Gig Harbor, WA, 98335

  • Hired to benchmark deterministic transport code with Geant4


  • C/C++
  • Geant4
  • CMake
  • TBB
  • bash
  • OpenGL
  • MCNP
  • Gaussian 09
  • MPI
  • OpenMP
  • ROOT
  • VisIt
  • Python
  • XML
  • MatLab
  • LaTeX
  • Doxygen