RUI: Low Energy Positronium Interactions with Atoms and Molecules in a Gas Environment

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This experimental research program focuses on the understand of basic interactions between positronium (a system with one electron and one positron bound together) and atoms and/or molecules in a gas environment. At the heart of this research is a newly developed Age-Momentum Correlation apparatus designed to observe positronium formed. This apparatus has already enabled the first quantitative observation of positronium at thermal energies with a High-Purity Germenium (HPGe) detector, demonstrating an unprecedented precision and range for the technique. With the power of the technique firmly established, measurements of the momentum-transfer cross-section for positronium scattering off atoms and/or molecules will be measured in a wider variety of gases, over a broader energy range (below 6.8 electron volts), and with greater precision than any previous experiment. Furthermore, it will be directly sensitive to pick-off annihilation (the decay of the electron and positron into gamma rays) in a new and more direct way, allowing new insights into this process. The broader impact of the program involves undergraduate student education as well as applications to biological systems.