Acquisition of Low Background High-Resolution Gamma Spectrometers for Research and Undergraduate Student Training

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This grant will support the acquisition of two high-resolution gamma spectrometers for faculty research and undergraduate student training in the Geology Department and Environmental Science Program at William & Mary. The spectrometers will enable precise measurements of naturally occurring gamma-emitting radionuclides from isotopes of uranium, thorium, potassium, and radium present in rocks and sediments worldwide, along with artificial isotopes of cesium and plutonium in air, soil, and sediment generated by the nuclear fuel and weapons processes. Importantly, these instruments will give us the capability to date sedimentary layers and thus be used to help reconstruct regional pollution histories and better understand Arctic climate change. Because sample preparation is simple for gamma spectrometry and the instruments have long-term stability, the spectrometers will be used to support undergraduate research training, augment undergraduate courses and laboratory exercises, and will provide educational outreach opportunities to faculty and students at Thomas Nelson Community College, a local two-year community college.The gamma spectrometers acquired will support a wide range of ongoing research projects at William & Mary and the Virginia Institute of Marine Sciences by providing precise ultra-trace measurements of radionuclide concentrations in environmental samples. The design of the instrumentation allows for optionally analyzing a single sample from opposing sides using both detectors and timed measurements to record coincident and anti-coincident pulses, a configuration that that will enable greatly improved detection limits for cosmogenic 22Na and for radionuclide measurements on small sample masses required by sediment core research. A major goal of existing research at William & Mary is to generate high-resolution reconstructions of past climate changes in the Pleistocene and Holocene at sites in Greenland, Norway, Svalbard, and the Faroe Islands from lake sediment cores. A second project that will be supported by this equipment acquisition aims to better understand radon sources in the Atlantic Coastal Plain, an area previously believed to have low uranium and radon potential. This instrumentation will support these two projects, and broadly equip researchers at William & Mary and the Virginia Institute of Marine Sciences studying salt marsh development and sedimentation in continental margin environments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.