Lawrence Livermore National Laboratory



Brett Isselhardt

Deputy Group Leader, Chemical and Isotopic Signatures
Nuclear and Chemical Sciences Division


 +1 925-424-3347


DegreeDiscipline/Institution
PhD Nuclear Engineering
University of California, Berkeley
BS Physics with Honors
Westmont College

Research Interests

Brett Isselhardt is a nuclear engineer in the Nuclear and Chemical Sciences Division at LLNL and is a deputy group leader for the Chemical and Isotopic Signatures (C&IS) group. He originally joined the C&IS group during his graduate studies, spending two years as a National Technical Nuclear Forensics Center post-doctoral fellow, and has been a member of the group for more than ten years. His research is centered on developing new techniques and methods for application to nuclear forensics, nonproliferation, and national security. His primary focus has been on the development of resonance ionization mass spectrometry (RIMS) for these applications, including the establishment of a state-of-the-art RIMS research facility at LLNL in 2015.

Isselhardt’s research interests include nuclear forensics and the security of nuclear materials in general (for examples: safeguards, nonproliferation, and illicit trafficking). He prefers to take a broad view of the possible solutions to hard problems, including technical and political approaches. His work has centered on developing RIMS to measure actinide isotope ratios in nuclear materials, with an emphasis on the atomic physics and atom-laser interactions driving the ionization process. He has also studied plutonium oxide morphology using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). In addition, he has worked on a materials analysis team focused on understanding the micro- and nano-scale structure in fallout debris from historical US tests using a variety of techniques including gamma spectroscopy, autoradiography, secondary ionization mass spectrometry (SIMS), SEM, and EDS.

Honors and Awards

  • NTNFC Nuclear Forensics Post-doctoral Fellow, 2011, LLNL
  • Lawrence Scholar Fellowship, 2006, LLNL
  • Nuclear Science for National Security Fellowship, 2006, LLNL
  • Student Instructor of the Year, Nuclear Engineering, 2004, UC Berkeley
  • Kenneth Monroe Award, 2003, Westmont College
  • Physics Department Senior of the Year, 2003, Westmont College

Selected Publications

Isselhardt, B.H., Prussin, S.G., Savina, M.R., Willingham, D.G., Knight, K.B., Hutcheon, I.D., "Relative Ionization Probabilities for Resonance Ionization Mass Spectrometry: The Influence of Laser Induced Bias on Uranium Isotope Ratios", J. Anal. At. Spectrom., submitted, 2014. LLNL-JRNL-648449

Isselhardt, B.H., D.G. Willingham, M.R. Savina, K.B. Knight, I.D. Hutcheon, "Progress in the Development of RIMS for Quantifying Actinide Isotope Ratios for Nuclear Forensics Applications", INMM 54th Annual meeting conference proceedings, LLNL-PROC-638541, in press, 2013.

Cassata, W.S., Prussin, S.G., Knight, K.B., Hutcheon, I.D., Isselhardt, B.H., Renne, P.R., "When the dust settles: Applications of noble gases to nuclear forensic research", Anal. Chem., LLNL-JRNL-635800, in review, 2013.

Isselhardt, B. H., "Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability", University of California, Berkeley, 2012

Isselhardt, B. H., Savina, M. R., Knight, K. B., Pellin, M. J., Hutcheon, I. D., and Prussin, S. G., "Improving Precision in Resonance Ionization Mass Spectrometry: Influence of Laser Bandwidth in Uranium Isotope Ratio Measurements", Anal. Chem., 2011, 83, 2469-2475

Knight, K. B., Savina, M. R., Isselhardt, B. H., Hutcheon, I. D., Prussin, S. G., and Pellin, M. J., "Uranium resonance ionization mass spectrometry in natural U-silicate", Proceedings in Radiochemistry, 2011, 1, 37-43

Levine, J., Savina, M., Dauphas, N., Davis, A., Isselhardt, B., Knight, K., Lewis, R., Pellin, M. & Stephan, T., First four-isotope measurements of chromium in presolar SiC grains, Lunar and Planetary Institute Science Conference Abstracts, 2009, 40, 1982

Daniel H. Chivers, Bethany F. Lyles Goldblum, Brett H. Isselhardt, Jonathan S. Snider, "Before the Day After: An Application of Nuclear Forensics to Prevent Nuclear Terrorism", Arms Control Today, July/August 2008


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