My primary focus is the development of accurate nuclear reaction cross sections used in radiochemical analysis techniques to determine device performance assessments of historical underground tests (UGT's) for the Stockpile Stewardship Program. I have also applied this knowledge to develop a radiochemical diagnostic capability on the National Ignition Facility (NIF). Recent work has explored the impact of atomic processes affecting the populations of nuclear excited states and their influence on radiochemistry on the NIF. Most recently I have worked on Quantification of Uncertainties in the production of fission fragments and their use in determining fission yields from UGT's.
I am also interested in the nuclear physics affecting the creation of atomic nuclei in massive stars and supernova physics. This involves theory and experiment. My PhD thesis and subsequent work focused on nucleosynthesis in the Neutrino-Driven Wind in core collapse supernovae and the astrophysical site of the r-process.
Hoffman, R.D., Zimmerman, G.A., Chen, M., & Cerjan, C., "Nuclear Plasma Interactions on the National Ignition Facility",
Roberts, L., Woosley, S.E. & Hoffman, R.D. "Integrated Nucleosynthesis in the Neutrino-Driven Wind",
Hoffman, R.D., Sheets, S.A., Burke, J.T., Scielzo, N.D., & Norman, E.B. et al. "Reaction Rate Sensitivity of Ti-44 Production in Massive Stars and Implications of a Thick Target Yield Measurement of Ca-40(a,g)Ti-44,
Fisker, J.L., Hoffman, R.D., & Pruet, J., "On the Origin of the Lightest Molybdenum Isotopes",
Colvin, J., Cerjan, C., Hoffman, R.D., et al., "Radiochemical Tracers as a Mix Diagnostic for the Ignition Double-Shell Capsule",
Hoffman, R.D., Mueller, B., & Janka, H.T., "Nucleosynthesis in O-Ne-Mg Supernovae",
Pruet, J., Hoffman, R.D., Woosley, S.E., Janka, H.T., & Buras, R., "Nucleosynthesis in Early Supernova Winds II. The Role of Neutrinos",