The Positron Research Group conducts experiments using positrons – the most accessible form of antimatter. The experiments are based around two positron beamlines, which are unique within Australia and represent world leading infrastructure in positron experimental research. Research conducted using these beamlines has spanned a wide range of different Physics, including fundamental atomic and molecular scattering, materials science and medical physics applications.
The beamlines use buffer gas trapping technology, which allows us to condition the positron beams for different uses. The positron are trapped and cooled to room temperature before being formed into a pulsed beam. This beam is magnetically confined and is tuneable in energy with the ability to optimise either the energy width or the temporal spread of the pulsed beam, depending on the intended application.
High energy resolution allows us to study low-energy scattering processes, probing the fundamental interactions in antimatter-matter scattering, and has led to world leading accuracy for the measurement of positron scattering. Current investigations include the search for positron and positronium scattering resonances and positron-atom or -molecule bound states, which are quantum processes of fundamental interest due to the many-body nature of the interaction. Detailed measurements provide a stringent test for theoretical calculations and allows us, in collaboration with theoretical colleagues, to refine our understanding of these processes.
A further, novel, research program uses the pulsed positron beam to produce positronium, the bound state of a positron and electron. This positronium beam is then used to probe interactions with atoms and molecules to investigate the unique scattering dynamics that arise with such a light, neutrally charged projectile.
Applications of our understanding of positron and positronium interactions are found in Positron Emission Tomography, which is a broadly used medical imaging technique. Our research program in this area makes measurements of positron and positronium scattering with biomolecules. We use this information, in conjunction with theorists and transport modelling, to better understand the underlying processes leading to radiation transport and damage mechanisms due to the introduction of positrons to biological systems.
Our group has collaborations with a wide range of other experimentalists and theorists from across the word, which provides a vibrant research environment and exposure to a wide range of different ideas and research techniques. We have a regular exchange of personnel with our colleagues that provides constant renewal and testing of ideas.