Current Research Interests
Dr. Bogard manages and operates Oak Ridge National Laboratory's Dosimetry Applications Research Calibration Laboratory (DOSAR CalLab), a 260 m2 facility built in 1987 which provides calibrated radiation exposures for personnel dosimetry research, dosimetry intercomparison studies, dosimetry performance test programs, training of health physics personnel, and radiobiology research. Sealed radioactive sources for b-, g, and neutron exposures are available in various configurations, and a Pantak model HF320 X-ray generator is used for reproducing NIST bremsstrahlung beam codes. The CalLab utilizes NIST-calibrated ion and extrapolation chambers and associated electronic equipment to provide NIST-traceable calibrated radiation exposures. A multi-purpose laboratory and office building with a conference room for training activities is located next to the DOSAR CalLab.
Funded research projects are directed toward the development of a small energy-independent neutron and heavy-charged-particle (HCP) spectrometer/dosimeter for use in medicine, space exploration and homeland security applications. The spectrometer detector consists of three-dimensional optical random access memories (3D ORAM) -- small cubes of a matrix material, such as a plastic polymer, doped with a bistable photochromic molecule such as spirobenzopyran (SP) or anthracene. We have demonstrated that neutron, proton and (HCP) radiations cause detectable changes in the fluorescence properties of 3D ORAM and that the effects are dependent on particle type and energy, thereby providing a novel and sensitive means for radiation detection and characterization. Current efforts are directed toward demonstrating that the spatial distribution and characteristics of particle tracks (defined by regions of altered fluorescence along the paths of high-LET neutron and HCP radiation) can be measured with useful precision in 3 dimensions within the bulk of the detector. Regions of change in fluorescence within the matrix (which define the tracks associated with individual particles) will be identified using two-photon excitation from crossed laser beams. The location of a fluorescence signal will be determined precisely at the intersection of the laser beams, and computer reconstruction of the fluorescence results will provide details of track structure. This capability will allow us to develop techniques for determining total energy and LET of the incident radiation.
Radiation Damage Dating of Archaeological Artifacts
Collaborative research with the University of Tennessee Department of Anthropology uses the natural thermoluminescence of materials such as quartz, feldspar and tooth enamel to provide estimates of the ages of archaeological artifacts. The intent is to establish a Center for Archaeological Dating as a resource for North American anthropologists and archaeologists.
Dr. Bogard has worked with commercial organizations and The University of Tennessee to provide professional training to health physicists and radiological engineers. He is co-author of a textbook, Problems and Solutions in Radiation Protection (Pergamon), and another scheduled for publication in 2002, Introduction to Statistics with Applications to Health Physics (Wiley).