Dynamics of physical flows measured by positron emission techniques

Abstract

Short lived positron emitting species are used to produce flow-following tracer particles to study flow dynamics in a technique known as positron emission particle tracking (PEPT). The photon pairs produced by positron annihilation are detected in time coincidence by arrays of high-speed position sensitive detectors. Reconstruction of consecutive annihilations are used to determine the near-instantaneous position of the tracer particle. Hence, the resulting bulk flow dynamics are derived, including residence times, velocities, accelerations, and related kinematic properties. The Department of Physics at the University of Cape Town uses PEPT to study dynamic physical processes, turbulent, and multiphase flows. Studies aim to address global challenge topics including problems in water scarce environments, reducing industrial wastes, and enhancing developments towards sustainable economies through improved process efficiencies and design led approaches. The PEPT Cape Town enterprise is discussed, including the development of flow metrology systems and complementary nuclear measurement techniques. Research encompasses four key themes: radioisotope tracer production, instrumentation & detector development, data acquisition & processing, and flow metrology.